刻蚀作为调控纳米材料和评估稳定性的研究

This work systematically established the atomic layer etching (ALE) technique for MOCVD in-situ $\text{SiN}_{\mathrm{x}}$. Achieving ultralow etching damage, with $\sim 110 \%$ and $\sim 220 \%$ improvement in surface morphology (RMS roughness) compared to asgrown and continuous etching wafers. Ultra-high etching precision with etching per cycle (EPC) of $1.13 ~\text{nm} /$ cycle was obtained. The mechanism of ALE was validated. This technique optimized the patterning of in-situ $\operatorname{SiN}_{x}$ passivation/dielectric on GaN, laying the foundation for realizing high-performance Si-based GaN HEMTs.

High-performance AlGaN/GaN MOSHEMTs on Si were demonstrated using atomic layer etching (ALE) for ohmic recess. The ALE technique enabled atomic-scale precision and effectively mitigated plasma-induced damage, leading to a smoother surface morphology ( R RMS ) and a notable reduction in contact resistance ( R c ) to 0.15 Ω·mm. The fabricated device exhibited enhanced maximum drain current ( I DS, MAX ), transconductance ( g m ), and a more positive threshold voltage ( V th ), along with suppressed gate and drain lag. Owing to the reduction in access resistance ( R S and R D ) and parasitic capacitance ( C GS and C GD ) extracted from small-signal modeling, the current-gain cut-off frequency ( f T ) and maximum oscillation frequency ( f MAX ) were enhanced to 58.7/121.5 GHz. At 28 GHz, the device achieved 3.02 W/mm output power ( P out ), 17.6% power-added efficiency ( PAE ), and 7.9 dB gain. In addition, power performance evaluated at both 6 GHz and 28 GHz showed clear improvements at 5 V and 10 V, with significantly greater enhancement observed at 20 V. These results demonstrate the effectiveness of ALE ohmic recess for high-power and high-performance mm-wave GaN-on-Si applications.

With a view to greater sustainability in the manufacturing process of semiconductor components, a modification of the atomic layer etching (ALE) process was successfully carried out on AlGaN material. Therefore, five different ALE modes, such as full-purge, half-purge, purge-free, continuous plasma, and bias-pulsing, were compared with each other. The focus of this work is on reducing the cycle time and, thus, the overall process time, while maintaining the quality with regard to surface morphology and contamination. First, parameter optimization in terms of ion energy, chlorine flux, modification, and removal time was carried out for the half-purge mode as the standard ALE mode. As a result, the etch per cycle (EPC) remained stable and low at (0.20 ± 0.02) nm/cycle for increasing ALE cycle numbers (25, 50, and 75), with no significant increase in surface roughness of 0.3 nm. It demonstrates the high precision and controllability of the standard recipe. The comparison of the five different ALE modes showed similar low roughness values and a consistent low EPC within the optimized process parameters for the full-purge, half-purge, purge-free, and continuous plasma modes. In contrast, the bias-pulsing mode exhibited a higher EPC of (0.33 ± 0.02) nm/cycle, along with surface chlorine contamination. Taking the process time into account, the continuous plasma mode is the best choice for reducing the processing time by up to 60%. Decreasing the processing time will also reduce gas and energy consumption, which positively affects production costs and improves sustainability.

Indium oxide (In2O3) is a promising channel material for advanced electronics, offering high electron mobility, a wide bandgap, and excellent compatibility with atomic layer deposition (ALD). However, conventional bottom-up ALD processes cannot achieve and sustain ultrathin crystalline layers owing to poor nucleation behavior and insufficient grain connectivity. Herein, we present an atomic layer etching (ALE) approach for In2O3 that combines hydrogen-plasma-assisted surface modification with acetylacetone (Hacac)-assisted ligand removal. Applying an ALD/ALE etch-back process incorporating this ALE method yielded In2O3 films down to 3 nm that preserved the (222) preferred orientation, as confirmed by grazing-incidence wide-angle X-ray scattering, and exhibited a reduction in root-mean-square roughness from 0.27 nm before etching to 0.17 nm after etching. This process simultaneously maintains the crystallographic order and smooth surface morphology in the ultrathin limit, leading to improved device performance. Therefore, the developed process is considered a viable fabrication route for scalable, high-quality crystalline oxide semiconductors for next-generation nanoelectronics.

ConspectusThe ability to synthesize nanoarchitected materials with tunable geometries provides a means to control their functional properties, with applications in biological, environmental, and energy fields. To this end, various bottom-up and top-down synthesis processes have been developed. However, many of these processes require prepatterning or etching steps, making them challenging to scale-up to complex, nonplanar substrates. Furthermore, the ability to integrate nanomaterials into hierarchical arrays with precise control of feature spacing and orientation remains a challenge.One approach to overcome these patterning challenges is the use of surface modification layers to guide the resulting geometry of nanomaterial architectures grown from the substrate. A powerful strategy to accomplish this is what we will refer to as "surface-directed assembly," where the resulting geometric parameters (feature size, shape, orientation) are predetermined by the initial surface layer. In particular, the use of Atomic Layer Deposition (ALD) to form a surface layer, followed by solution-based growth processes, has the ability to synthesize architected structures with tunable geometries on complex, nonplanar surfaces.Over the past decade, we have reported a series of studies where surface-directed assembly is used to synthesize ZnO nanowires (NWs) on top of a variety of substrates. In this case, a thin film of ZnO is deposited onto the substrate using ALD, which can guide the NW diameter, spacing, and angular orientation with respect to the substrate by controlling epitaxial relationships. Furthermore, we have shown that by depositing a submonolayer overcoat of a secondary material (e.g., amorphous TiO2), nucleation sites are partially blocked, which can further tune the spacing between nanowires while minimizing changes to their other geometric properties. This approach can be used to generate multilevel hierarchical structures, such as hyperbranched NW arrays with tunable control of each level of hierarchy using ALD. Finally, we have demonstrated that the tunable control of geometric parameters can be scaled-up to curved, nonplanar substrates. This highlights the power of ALD to conformally and uniformly deposit the seed layers on complex substrates with subnanometer precision.To complement these seeded hydrothermal approaches, we expanded this strategy to include conversion chemistry of the initial ALD seed layers. For example, by replacing ZnO with Al2O3 as the seed layer without changing the hydrothermal growth conditions, Al-Zn layered-double hydroxide nanosheets can be formed instead of nanowires. In another example of conversion chemistry, a solution anion-exchange process was used to incorporate sulfur into ALD metal oxide films. In both of these conversion processes, the properties of the initial ALD film enabled tuning of the resulting nanostructure geometry.In this Account, we describe the use of ALD to guide the growth of diverse nanomaterial systems, with tunable control over their geometry and composition. We further show how these approaches can be used to tune functional properties for a range of applications, including superomniphobic surfaces, antibiofouling coatings, and photocatalysis. We conclude with an outlook on how the combination of ALD and solution synthesis can enable future directions in scalable nanomanufacturing to overcome the limitations of traditional top-down and bottom-up approaches.

Atomic layer etching is a low-damage etching process that can precisely control the etching depth, which is desirable for the preparation of enhancement-mode recessed-gate GaN-based high electron mobility transistors (HEMTs). In this article, the etching damage induced by atomic layer etching (ALE) was investigated in detail. The atomic force microscopy (AFM) results showed that the ALE process did not significantly degrade the surface morphology. The interface traps’ density (<inline-formula> <tex-math notation="LaTeX">${D}_{\text {it}}$ </tex-math></inline-formula>), extracted from the conductance test, was as low as 0.7–<inline-formula> <tex-math notation="LaTeX">$1.2\times 10{^{{12}}}$ </tex-math></inline-formula>cm<inline-formula> <tex-math notation="LaTeX">${}^{\text {-2}}$ </tex-math></inline-formula>eV<inline-formula> <tex-math notation="LaTeX">${}^{\text {-1}}$ </tex-math></inline-formula> in the energy level range of 0.28–0.39 eV below the conduction band edge, demonstrating the low-damage advantage of the developed ALE process. XPS characterization has been performed to gain a better understanding of the origin of the interface traps. It was found from a transmission electron microscope (TEM) image that the amorphous layer formed by ALE was confined to a depth of 2 nm from the surface. The temperature-dependent measurements of the dual-gate structure demonstrated that the interface traps would induce surface leakage current, and the 2-D variable range hopping (2D-VRH) was the conduction mechanism of surface leakage current.

GaN is a key material in microelectronics that requires precise etching to meet technological demands. Plasma Atomic layer etching (ALE) is a promising process to achieve a defectless surface. However, the plasma/surface interaction mechanisms involved remain complex. In this work, we propose a multiscale model of GaN plasma ALE in chlorinated plasmas that combines a plasma module using a dynamic global model to describe Cl2/Ar plasmas, a sheath module described by a Monte Carlo model, and a surface module considering a kinetic Monte Carlo model. In addition, density functional theory calculations of Cl adsorption on GaN surfaces are used for a better description of the adsorption mechanisms. The surface module allows simulations of the GaN surface during ALE with an atomic-scale resolution. This multiscale approach enables comprehensive evolution of surface morphology, material composition, and etching products over time. Results reveal a self-limited etching behavior consistent with ALE principles and show that residual chlorine penetrating in shallow layers significantly impacts the etch per cycle. Our simulator provides a currently offline predictive framework that could contribute as a step toward future digital twin development to optimize and control GaN ALE processes.

Atomic layer etching (ALE) has emerged as a pivotal technique in the precise fabrication of two-dimensional (2D) materials, particularly molybdenum disulfide (MoS 2 ), which holds promise in the semiconductor industry due to its high mobility in monolayer form. The ability to precisely etch amorphous and crystalline MoS 2 films provides a pathway for controlling thickness, which is critical to achieving desired electrical and optical properties. Previous studies used MoF 6 and H 2 O in thermal ALE of MoS 2 . Here, we report studies of alternate sources of fluorination and oxygenation and evaluate their impact on thermal ALE of MoS 2 . Oxygen sources include water and ozone, and fluorine sources include HF/Pyridine and MoF 6 . Etch rates, uniformity, and surface chemistry post ALE were characterized using spectroscopic ellipsometry, atomic force microscopy, and X-ray photoelectron spectroscopy. Results indicated at ALE of amorphous MoS 2 with HF with either H 2 O or O 3 showed no signs of etching at 200 ºC or 250 ºC. Whereas the combination of MoF 6 + O 3 at 250 ºC on amorphous MoS 2 films exhibited an etch rate of 1.6 Å/cycle and a mass loss of 44 ng/cm 2 . Further MoF 6 + O 3 etching at 200 ºC showed a mass loss of 19 ng/cm 2 , similar to prior reports using MoF 6 + H 2 O at 200 ºC. Surface morphology showed little change from etching, but surface oxygen concentration increased. This research further expands the capabilities for atomic layer processing of 2D materials.

An atomic layer etching (ALE) process without purge has been developed for gate recess etching of AlGaN/GaN high electron mobility transistors (HEMTs). The process consists of repeating ALE cycles where Cl2/BCl3 plasma modifies the surface by chemisorption. The modified layer is removed by the subsequential Ar ion removal step. In this manner, AlGaN/GaN HEMTs with three different gate recess etching depths of (7.3 ± 0.5), (13.6 ± 0.5), and (21.0 ± 0.5) nm were fabricated. The determined etch per cycle (EPC) of ∼0.5 nm corresponding to one unit cell in the c-direction of GaN was constant for all recesses, illustrating the precision and controllability of the developed ALE process. The root-mean-square surface roughness was 0.3 nm for every etching depth, which corresponds to the roughness of the unetched reference. The electrical measurements show a linear dependence between threshold voltage (Vth) and etching depth. An enhancement mode (E-mode) HEMT was successfully achieved. A deeper gate recess than 20 nm leads to an increased channel resistance, lower saturation current, and higher gate leakage. Hence, a compromise between the desired Vth shift and device performance has to be reached. The achieved results of electrical and morphological measurements confirm the great potential of recess etching using the ALE technique with precisely controlled EPC for contact and channel engineering of AlGaN/GaN HEMTs.

Modern microelectronic components for high-power and high-frequency applications based on III-V compound semiconductors offer high break down voltage (GaN: 5 MV/cm and AlN: 15 MV/cm) at low specific on-resistance. However, it requires reliability and reproducibility of the production processes. Going to higher frequencies (5 GHz and beyond) and more integration in consumer electronics, smaller structure sizes are needed. This is going along with increasing demands on the manufacturing processes like dry etching. The main goal is to reach smaller and high controllable etching rates, going down to single atomic layers, low damage, and minimized surface roughness. Atomic layer etching (ALE) represents a key technology in order to achieve such requirements. An ALE process consists of two independent steps forming a repeatable cycle with a specific etching amount per cycle (EPC). First a surface modification is done by a chemical precursor i.e., adsorbing or oxidizing the surface. The second step is the removal of the modified layer, either physically by low energy non-reactive ion bombardment (Plasma Enhanced ALE [PEALE]) or chemically by a reactive species (Thermal ALE). The two steps are separated by an inert gas purge. This purging grants the removal of the chemistry after the first step, preventing further chemical reaction and transporting the chemical products out of the chamber after the second step. In this study, a PEALE conducted on different tools is used, for gate and contact recess study in a AlGaN/GaN heterostructure to form high electron mobility transistors (HEMT) with reduced ohmic contact resistance and threshold voltages. The results show a reduction of ohmic contact resistance at reduced forming temperatures and a linear dependence of the threshold voltage on gate recess depth. In order to determine the etching rate and roughness, atomic force microscopy (AFM) measurements were performed. The PEALE module is either integrated into a cluster tool consisting of atomic layer deposition (ALD) and chemical vapor deposition (CVD) or done in a combined ALD/ALE chamber. This opens the possibility of etching and depositing in-situ, reducing contamination and degradation of the substrate material. By this means, metal insulator semiconductor (MIS)-HEMTS with a recessed gate are studied. The monitoring of the individual processes is achieved by test structures like transfer length method structures (TLM) and metal oxide semiconductor (MOS), which showed the improved electric performance of these devices and may indicate unwanted interface issues, respectively. Additional, pre- and post-treatments could improve the interfaces further. The results will be presented and discussed in terms of ALE process development and optimization. This work was financially supported within the ALEStar project by the government of the Free-state of Saxony and the European Regional Development Fund under grant no. SAB 100402929.

Molybdenum dioxide (MoO2) has attracted significant attention as a high‐work‐function electrode material for next‐generation metal‐insulator‐metal (MIM) capacitors, particularly for stabilizing the rutile phase of TiO2 with a dielectric constant of 150. However, challenges such as stoichiometric variations in high‐aspect‐ratio structures and morphology degradation during reduction have limited its practical applications. To address these issues, a novel self‐limiting deposition and etching in atomic‐scale (SDEA) process is introduced. This approach combines atomic layer deposition (ALD) of MoOa (2 < a < 3) using Mo + O3, followed by atomic layer etching (ALE) of MoO3 using H2O. The process selectively removes MoO3 through etching, leveraging the self‐limiting nature of both reactions to achieve precise atomic‐scale control over oxidation states without morphology degradation. MoO2 films deposited using this method exhibit enhanced electrical performance, including a higher dielectric constant and reduced leakage current when employed as bottom electrodes in TiO2‐base metal‐insulator‐metal capacitors. This work provides a transformative solution for integrating MoO2 into cutting‐edge semiconductor devices, overcoming the limitations of existing deposition techniques. The SDEA process represents a significant advancement in material and process engineering, offering new possibilities for device miniaturization and performance enhancement.

Nano-steps, as classical nano-geometric reference materials, are very important for calibrating measurements in the semiconductor industry; therefore, controlling the height of nano-steps is critical for ensuring accurate measurements. Accordingly, in this study nano-steps with heights of 1, 2, 3 and 4 nm were fabricated with good morphology using atomic layer deposition (ALD) combined with wet etching. The roughness of the fabricated nano-steps was effectively controlled by utilizing the three-dimensional conformal ALD process. Moreover, the relationship between the surface roughness and the height was studied using a simulation-based analysis. Essentially, roughness control is crucial in fabricating nano-steps with a critical dimension of less than 5 nm. In this study, the minimum height of a nano-step that was successfully achieved by combining ALD and wet etching was 1 nm. Furthermore, the preconditions for quality assurance for a reference material and the influencing factors of the fabrication method were analyzed based on the 1 nm nano-step sample. Finally, the fabricated samples were used in time-dependent experiments to verify the optimal stability of the nano-steps as reference materials. This research is instructive to fabricate nano-geometric reference materials to within 5 nm in height, and the proposed method can be easily employed to manufacture wafer-sized step height reference materials, thus enabling its large-scale industrial application for in-line calibration in integrated circuit production lines.

The etching of p‐GaN requires extremely strict control over etching depth and morphology; otherwise, it will result in poor electrical characteristics. This work uses ALD(Atomic layer deposition) in situ N2 plasma and postanneal‐assisted passivation to effectively recover the electrical properties degraded by p‐GaN etching. Compared to unpassivated devices, this approach eliminates surface oxygen bonds, recovering drain current from 10 to 126 mA mm−1, reducing gate leakage by an order of magnitude, achieving an ON/OFF current ratio exceeding 108, a breakdown voltage of 930 V at 1 μA mm−1, and effectively suppressing current collapse.

A crack-free and residue-free transfer technique for large-area, atomically-thin 2D transition metal dichalcogenides (TMDCs) such as MoS2 and WS2 is critical for their integration into next-generation electronic devices, either as channel materials replacing silicon or as back-end-of-line (BEOL) components in 3D-integrated nano-systems on CMOS platforms. However, cracks are frequently observed during the debonding of TMDCs from their growth substrates, and polymer or metal residues are often left behind after the removal of adhesive support layers via wet etching. These issues stem from excessive angular strain accumulated during debonding and the incomplete removal of support layers due to their low solubility. In this study, we developed a novel debonding strategy along with an optimized etching protocol to address these challenges. Characterization using Raman spectroscopy, photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and optical microscopy (OM) confirmed that the optimized process enables clean, crack-free, and morphologically intact MoS2 films. The success of the crack-free and residual-free transfer is attributed to two key factors: (1) the suppression of mechanical bending during debonding, which eliminates bending-induced crack formation; and (2) the precise control of etchant concentration, reaction duration, and post-etch rinsing steps, which ensures the complete removal of the support layer without damaging the MoS2 film. Using commercially available fab tools such as wafer bonders and debonders, we successfully demonstrated the clean transfer of a 2-inch monolayer MoS2 film with a high transfer yield of 95%, highlighting the practical applicability of this process for scalable device fabrication.

A plasma‐assisted atomic layer deposition (PE‐ALD) process is reported for creating ohmic contacts to n‐type GaN that combines native oxide reduction, near‐surface doping, and encapsulation of GaN in a single processing step, thereby eliminating the need for both wet chemical etching of the native oxide before metallization and thermal annealing after contact formation. Repeated ALD cycling of trimethyl aluminum (TMA) and high‐intensity hydrogen (H2) plasma results in the deposition of a sub‐nanometer‐thin (≈8 Å) AlOx layer via the partial transformation of the GaN surface oxide into AlOx. Hydrogen plasma‐induced nitrogen vacancies in the near‐surface region of GaN serve as shallow donors, promoting efficient out‐of‐plane electrical transport. Subsequent metallization with a Ti/Al/Ti/Au stack results in low contact resistance, ohmic behavior, and smooth morphology without requiring annealing. This electrical contracting approach thus meets the thermal budget requirements for Si‐based complementary metal–oxide–semiconductor structures and can facilitate the design and fabrication of advanced GaN‐on‐Si heterodevices.

We fabricated vertical channel thin film transistors (VTFTs) with a channel length of 130 nm using an ALD In–Ga–Zn–O (IGZO) active channel and high-k HfO2 gate insulator layers. Solution-processed SiO2 thin film, which exhibited an etch selectivity as high as 4.2 to drain electrode of indium-tin oxide, was introduced as a spacer material. For the formation of near-vertical sidewalls of the spacer patterns, the drain and spacer were successively patterned by means of two-step plasma etching technique using Ar/Cl2 and Ar/CF4 etch gas species, respectively. The SiO2 spacer showed smooth surface morphology (R q = 0.45 nm) and low leakage current component of 10–6 A cm−2 at 1 MV cm−1, which were suggested to be appropriate for working as spacer and back-channel. The fabricated VTFT showed sound transfer characteristics and negligible shifts in threshold voltage against the bias stresses of +5 and −5 V for 104 s, even though there was abnormal increase in off-currents under the positive-bias stress due to the interactions between hydrogen-related defects and carriers. Despite the technical limitations of patterning process, our fabricated prototype IGZO VTFTs showed good operation stability even with an ultra-short channel length of 130 nm, demonstrating the potential of ALD IGZO thin film as an alternative channel for highly-scaled electronic devices.

In order not to have our children inherit a huge problem in the future, we quickly have to realize the energy transition to renewable sources, which requires also energy storage devices and, thus, Li ion batteries. Although significant progress has been made during recent years regarding battery capacitance, cycle life time, deterioration, and fast charging capabilities, any further improvement becomes increasingly more difficult. The reason for this is manifested in the top-down approach, which quickly delivers results, and thus products, by screening the parameter space and evaluating available options. At this point, however, further improvements often require a deep, fundamental understanding of all processes, and a change to a bottom-up approach is highly recommended, if not even essential. Using Scanning Tunneling Microscopy movies, I will show in my talk how a small change in adatom formation energy and adatom diffusion barrier leads to a huge morphology change of the growing film. After providing the insights to the well-known homoepitaxial growth modes, I will introduce one specific atomic barrier that leads to an instability and triggers 3D growth. The 2D analogous of this barrier at a step edge, leads to dendritic island shapes, and the combination of both, the 2D and 3D instability, leads to dendrites as observed also in the batteries. With this in mind, I will show the dualism between adatoms and vacancies, which naturally explains also the equivalent, inverse growth modes during etching or dissolution including their instabilities. From here we will switch gears and focus on polycrystalline film aspects, and, thus, the grain boundary network. I will show, again on the atomic scale, how the grain boundary energy determines the surface structure from extremely rough to flat and smooth. Quite surprisingly, I will further demonstrate how a tiny variation in the dilute adatom/vacancy equilibrium-pressure on the surface, during growth or dissolution, can setup pressures variations in the grain boundary network that exceed the pressure of the deepest point of all our world seas: the Mariana Trench. These enormous compressive (and tensile) stresses are to a large extent reversible. However, due to the differences in diffusion constants in combination with the huge reservoir of grain boundary volume in the film, complications arise on the atomic scale at the triple point/lines, where the grain boundaries penetrate the surface. Mass accumulation or depletion leads to hillocks and grooves. Moreover, the remaining accumulated intrinsic film stress can also trigger whisker growth, which, on the basis of the involved atomic processes, clearly has to be distinguished from dendritic growth. Although fundamentally still not understood, whisker growth leads to many failures, like short circuits in electronic devices and batteries. Their penetrating forces can be enormous, pushing through even hard oxide layers and films (and the SEI). As many of the described effects play a major and critical role in Li ion batteries, and while I realize that I am adding seemingly hopeless, additional complexity, I will finally provide some basic strategies and concepts that we learned on how to tune and influence the previously mentioned effects efficiently on the atomic scale by using additives.

This article discusses a method for forming black silicon using plasma etching at a sample temperature range from −20 °C to +20 °C in a mixture of oxygen and sulfur hexafluoride. The surface morphology of the resulting structures, the autocorrelation function of surface features, and reflectivity were studied depending on the process parameters—the composition of the plasma mixture, temperature and other discharge parameters (radical concentrations). The relationship between these parameters and the concentrations of oxygen and fluorine radicals in plasma is shown. A novel approach has been studied to reduce the reflectance using conformal bilayer dielectric coatings deposited by atomic layer deposition. The reflectivity of the resulting black silicon was studied in a wide spectral range from 400 to 900 nm. As a result of the research, technologies for creating black silicon on silicon wafers with a diameter of 200 mm have been proposed, and the structure formation process takes no more than 5 min. The resulting structures are an example of the self-formation of nanostructures due to anisotropic etching in a gas discharge plasma. This material has high mechanical, chemical and thermal stability and can be used as an antireflective coating, in structures requiring a developed surface—photovoltaics, supercapacitors, catalysts, and antibacterial surfaces.

Hydrogen fuel cell bipolar plates demand surfaces with an atomically smooth morphology and stable electrochemical interfaces to minimize contact resistance and corrosion degradation. While nickel-titanium (NiTi) alloys offer inherent advantages for this role, their practical deployment is hindered by persistent surface defects (e.g., microcracks and oxide inclusions) introduced during additive manufacturing. Here, we propose an ultrasonic-electrochemical hybrid polishing strategy that synergistically integrates in situ electrochemical dissolution with ultrasonic cavitation-induced mechanical activation, achieving dual interfacial engineering: (1) atomic-scale material removal via dislocation-mediated plasticity and (2) self-passivating oxide layer formation. Molecular dynamics simulations reveal that ultrasonic excitation reduces the critical shear stress for dislocation nucleation, enabling defect-free surfaces at specific etching depths. (3) The synergistic coupling of ultrasonic, electrochemical, and mechanical interactions facilitates the elimination of residual powdery particulates on additively manufactured NiTi bipolar plates, thereby reducing interfacial contact resistance. This work establishes a paradigm of energy-field-assisted interfacial engineering for metallic bipolar plates, bridging atomic-scale mechanisms with macroscale device performance.

Wet chemical etching of silicon has been a topic of significant interest due to its importance in microelectromechanical systems (MEMS), nanotechnology, and semiconductor device fabrication. Many kinds of MEMS components (e.g., cavity, diaphragm, cantilever, etc.) are fabricated through wet anisotropic etching-based silicon bulk micromachining of {100} and {110} oriented silicon wafers. Wet anisotropic etching of silicon is primarily carried out using alkaline solutions such as potassium hydroxide (KOH), tetramethylammonium hydroxide (TMAH), etc. The etching rate of Si{111} crystal planes is significantly slower compared to other planes like Si{100} and Si{110} as a result of its atomic structure and surface properties. Therefore, the Si{111} crystal plane is of particular interest owing to its unique properties and potential applications. In this work, we report the wet anisotropic etching characteristics of Si{111} in KOH with addition of isopropyl alcohol (IPA). Surface morphology of the etched Si{111} surfaces was examined using confocal laser scanning microscopy (CLSM). In all experimental scenarios, the Si{111} crystal surface gives rise to triangular etch pits, the size and depth of these etch pits are contingent upon the etching time. Following your advice, we revised the abstract phrase “become more sharper” in the summary and quantified the angle data of the triangle. The entire statement has been specifically modified to Furthermore, when the additive IPA is incorporated into the etchant, the corners of these triangular etch pits on the surface transitions from rounded to sharp (with each angles of approximately 60°), indicating that the overall shape of these triangular etch recesses approaches that of an equilateral triangle. In addition, the theory of crystal cleavage is introduced to explain the formation mechanism of surface triangular flat-bottom etch pits during the etching process of Si{111} crystal planes. At the same time, the relevant experiments on Si{111} samples with a SiO2 mask layer on the surface have been completed, and the results verify the correctness of the analysis of the relevant mechanism. The relevant results and mechanism presented in this article are of large significance for engineering applications in both academic and industrial laboratories.

Subject of study. Multilayer samples of porous silicon produced using a variety of electrochemical etching process parameters were studied. Goal of work. An experimental study of production techniques for multilayer porous silicon was conducted, and techniques for fine-tuning the volume and surface properties for use in nanoelectronic devices were developed. Method. The surface morphology was studied by atomic force microscopy and scanning electron microscopy. The surface-layer porosity was studied using X-ray reflectometry. The electron structure of the surface was studied using ultrasoft X-ray emission spectroscopy. The optical properties were determined using photoluminescence spectra. Main results. It was found that stepwise increases in electrochemical anodizing current through a monocrystalline silicon substrate produce multilayer structures in which the layers have different morphologies, surface compositions, and porosity values. Photoluminescence was found to be determined primarily by the composition of the top layer. The effects of gradually increasing the current density while holding the overall etching time constant are also discussed in detail. Practical significance. The research results for the effect of etching mode on porous-silicon morphology and optical properties will be used for the development of nanoelectronic devices based on porous structures.

Wet etching of (001) β-Ga2O3 was performed using a standard lithographic developer—an aqueous solution of 2.38 wt% tetramethylammonium hydroxide (TMAH)—at moderate temperatures of 25 °C and 40 °C. At both temperatures, the chemically-mechanically polished surfaces, which consisted of terraces with numerous pits and, in some samples, one- to two-monolayer-high islands, were gradually smoothed through a layer-by-layer etching process. This resulted in a well-defined step-and-terrace surface morphology characterized by pit-free, atomically flat terraces and monolayer steps (~0.56 nm). These findings indicate that developer-based etching offers a simple yet highly effective approach for preparing (001) β-Ga2O3 surfaces for subsequent epitaxial growth or device fabrication.

Titanium nitride (TiN) is a robust ceramic material extensively used in semiconductor manufacturing due to its exceptional hardness, chemical resistance, and thermal stability. These properties make TiN an ideal choice for applications such as gate electrodes and diffusion barriers. Additionally, TiN serves as a hard mask in semiconductor fabrication, providing high chemical resistance and compatibility with high-aspect-ratio patterning. However, the intrinsic hardness and chemical inertness of TiN necessitate the development of effective etching techniques. Conventional methods such as plasma etching, atomic layer etching (ALE), and chemical mechanical polishing (CMP) provide precise control but are often impeded by slow processing speeds, high operational costs, and the potential for material damage. Additionally, achieving high selectivity against copper (Cu) and dielectric materials remains a significant challenge. Plasma etching frequently suffers from low selectivity for Cu and the risk of metal damage; while ALE offers improved process control, it still requires protective strategies for Cu. CMP, on the other hand, lacks material selectivity and may induce mechanical damage to both Cu and dielectric layers. In contrast, wet etching has emerged as a promising technique for TiN removal due to its superior selectivity over dielectric materials and its ability to minimize substrate damage. Furthermore, wet etching presents advantages in terms of lower equipment complexity and reduced operational costs, making it economically favorable for large-scale semiconductor manufacturing. To enhance etching efficiency in wet etching processes, this study proposes two distinct approaches. The first approach is inspired by the commercially used Standard Clean 1 (SC1) solution, an alkaline mixture composed of H₂O, NH₄OH, and H₂O₂. In the SC1 system, hydrogen peroxide (H₂O₂) acts as an oxidizing agent, decomposing under alkaline conditions to generate hydroperoxide ions (HO₂⁻). These reactive species facilitate the formation of soluble titanium complexes through interactions with Ti ions, thereby promoting material removal(Figure1). Building upon this mechanism, we propose substituting water with an organic solvent to reduce the surface tension of the etching solution. A lower surface tension enhances the wettability of the solution on TiN surfaces, improving its ability to penetrate surface features and interact with the TiN layer. This improved interfacial compatibility is expected to enhance removal efficiency. Preliminary experimental results demonstrate that replacing water with 70 wt% ethyl acetate in an SC1-like solution significantly increases the etching rate, from 5.66 nm/min to 9.88 nm/min, as shown in Figure 3. The second approach draws inspiration from mechanisms reported in the selective wet etching of silicon nitride (Si₃N₄), where SN1- and SN2-like reactions are employed. In this system, H₂PO₄⁻, a weak nucleophile derived from H₃PO₄, substitutes the NH₂ group on the Si₃N₄ surface via an SN1-like mechanism. This is followed by the hydrolysis of Si–N bonds through an SN2-like attack by water, ultimately forming Si–OH and facilitating removal. Analogously, we explore a chlorination-based strategy, as illustrated in Figure 2, wherein the chlorinating agent, trichloroisocyanuric acid (TCCA), is utilized to generate electrophilic chlorine species (Cl⁺) or chlorine radicals (Cl•) capable of reacting with TiN. This reaction pathway facilitates the formation of volatile titanium tetrachloride (TiCl₄), which can be easily removed from the substrate surface. Prior studies have confirmed the efficacy of such chlorination reactions in gas-phase plasma environments. In our wet chemical system, this chlorination approach similarly enhances the etching rate, with results showing an increase from 1.12 nm/min to 9.34 nm/min in the presence of chlorinating reagents, as shown in Figure 4. To elucidate the fundamental etching mechanisms underlying these two approaches, systematic investigations into the effects of etchant concentration, temperature, and oxidizing agent presence on the etching rate and material selectivity are being conducted. High-performance liquid chromatography–mass spectrometry (HPLC-MS) and nuclear magnetic resonance (NMR) spectroscopy were employed to identify and confirm the formation of titanium-containing etching byproducts. Additionally, post-etching surface morphology and chemical bonding alterations were analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), respectively. Through comprehensive mechanistic understanding and parameter optimization, this study aims to establish a controllable and efficient TiN wet etching process suitable for advanced semiconductor manufacturing applications. Keywords: Titanium nitride, wet etching, organic solvent, chlorination Figure 1

The "shuttle effect" and slow reaction kinetics caused by the diffusive polysulfides (LiPSs) in lithium-sulfur batteries have seriously hindered the superiorities of high theoretical capacity and energy density of sulfur cathode. Metal compounds serve as cathode carrier materials for lithium-sulfur batteries can adsorb LiPSs and accelerate the sulfur redox reaction. Compared with monometallic systems, bimetallic components usually expose richer active sites, which facilitates the kinetics of LiPSs during the redox process. However, due to the limitation of morphology and structure, the catalytic capacity of single metal atom and the synergistic effect between bimetal atom are still not fully utilized, leading to the still poor reaction kinetics. Especially, their application effect in thick electrode with high sulfur load is significantly reduced. In this study, chemical etching reaction was utilized to convert zeolitic imidazolate framework (ZIF) 67 into a polyhedral hierarchical structured material stacked with layered double hydroxide (NiCo-LDH) nanosheets, and based on this, it was transformed into nickel cobalt sulfoselenide (NiCoSSe) with quaternary hierarchical structure. The bimetallic sulfoselenide obtained by this strategy retain the high specific surface area of the ZIF structure, thus providing more active sites for adsorption of LiPSs and catalyzing sulfur redox. Importantly, it was demonstrated by density-functional theory (DFT) calculations that, selenium doping can further enhance the interaction between Ni and Co atoms in NiCoSSe, which promotes the conversion of LiPSs and significantly improves the redox kinetics of the battery. An initial specific capacity of up to 1093.4 mAh g-1 at a current density of 0.1C as well as a capacity retention of 98.2 % after 500 charge-discharge cycles at a current density of 2C were obtained based on the cathode with NiCoSSe carrier. By systematically investigating the synthesis of bimetallic sulfoselenide compounds and their enhancement effects on the reaction kinetics of lithium-sulfur battery cathode, this study will provide a detailed reference for the conformational relationship between the structure of quaternary NiCoSSe materials and electrochemical performance.

PEGylated graphene oxide (GO) has shown potential as NIR converting agent to produce local heat useful in breast cancer therapy, since its suitable photothermal conversion, high stability in physiological fluids, biocompatibility and huge specific surface. GO is an appealing nanomaterial for potential clinical applications combining drug delivery and photothermal therapy in a single nano-device capable of specifically targeting breast cancer cells. However, native GO sheets have large dimensions (0.5-5 μm) such that tumor accumulation after a systemic administration is usually precluded. Herein, we report a step-by-step synthesis of folic acid-functionalized PEGylated GO, henceforth named GO-PEG-Fol, with small size and narrow size distribution (∼30 ± 5 nm), and the ability of efficiently converting NIR light into heat. GO-PEG-Fol consists of a nano-GO sheet, obtained by fragmentation of GO by means of non-equilibrium plasma etching, fully functionalized with folic acid-terminated PEG2000 chains through amidic coupling and azide-alkyne click cycloaddition, which we showed as active targeting agents to selectively recognize breast cancer cells such as MCF7 and MDA-MB-231. The GO-PEG-Fol incorporated a high amount of doxorubicin hydrochloride (Doxo) (>33%) and behaves as NIR-light-activated heater capable of triggering sudden Doxo delivery inside cancer cells and localized hyperthermia, thus provoking efficient breast cancer death. The cytotoxic effect was found to be selective for breast cancer cells, being the IC50 up to 12 times lower than that observed for healthy fibroblasts. This work established plasma etching as a cost-effective strategy to get functionalized nano-GO with a smart combination of properties such as small size, good photothermal efficiency and targeted cytotoxic effect, which make it a promising candidate as photothermal agent for the treatment of breast cancer.

To enhance the precision and reliability of early disease detection, especially in malignancies, an exhaustive investigation of multi-target biomarkers is essential. In this study, an advanced integrated electrochemical biosensor array that demonstrates exceptional performance was constructed. This biosensor was developed through a controllable porous-size mechanism and in-situ modification of carbon nanotubes (CNTs) to quantify multiplex biomarkers-specifically, C-reaction protein (CRP), carbohydrate antigen 125 (CA125), and carcinoembryonic antigen (CEA)-in human serum plasma. The fabrication process involved creating a highly ordered three-dimensional inverse-opal structure with the CNTs (pCNTs) modifier through microdroplet-based microfluidics, confined spatial self-assembly of nanoparticles, and chemical wet-etching. This innovative approach allowed for direct in-situ modification of nanomaterial onto the surface of electrode array, eliminating secondary transfer and providing exceptional control over structure and stability. The outstanding electrochemical performance was achieved through the synergistic effect of the pCNTs nanomaterial, aptamer, and horseradish peroxidase-labeled (HRP-) antibody. Additionally, the integrated biosensor array platform comprised multiple individually addressable electrode units (n = 11), enabling simultaneous multi-parallel/target testing, thereby ensuring accuracy and high throughput. Crucially, this integrated biosensor array accurately quantified multiplex biomarkers in human serum, yielding results comparable to commercial methods. This integrated technology holds promise for point-of-care testing (POCT) in early disease diagnosis and biological analysis.

Multifunctional two-dimensional nanosheet materials have attracted attention in biomedical fields due to their unique physiochemical and biological properties. Interactions between intestinal stem cells and Engineered Nanomaterials (ENMs) are an essential area in research with the growing diagnosis of gastrointestinal (GI) diseases. One unique type of two-dimensional metal carbide nanomaterial, niobium carbide (Nb2 C), has shown promising properties for potential applications in this field, such as biocompatibility, stability, and high photothermal conversion efficiency. In this study, Nb2 C nanosheets were prepared by spark plasma sintering and HF etching. Various concentrations of Nb2 C nanosheets were placed inside intestinal organoids, which mimic the real functions of an intestinal system. These organoids were formed from intestinal crypts that were isolated from mice and grew into self-maintained systems. Through growth analysis, surface area calculations, and cell viability tests, it was concluded that an optimal concentration of nanosheets exists that may offer stimulation to intestinal cells while having no toxic effects. A high concentration of nanosheets in the organoids inhibited growth, whereas the control and low concentration of nanosheets showed no reduced growth rate. When placed under infrared exposure, the organoids with nanosheets offered stimulation and showed more viability after time as compared to the control organoids with no nanosheets. These results show overall potential benefits of placing low concentration Nb2 C nanosheets in intestinal systems to protect and stimulate cell survivability when undergoing various treatments.

Laser-induced graphene (LIG) is a promising material for flexible and stretchable electronics due to its porous structure and high electrical conductivity. However, its mechanical fragility under strain limits practical applications. Here, we present a simple yet effective dual-treatment method, low-temperature annealing at 180°C followed by oxygen plasma etching—to enhance LIG's strain resistance. This process induces a dense fractal fiber network that preserves conductivity while improving structural stability. The treated LIG exhibits a reduced gauge factor (GF) of 7.43, approximately half that of untreated LIG, indicating lower sensitivity to strain-induced resistance changes. Scanning electron microscopy (SEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) analyses reveal improved fiber connectivity, enhanced graphitization, and reduced oxygen defects. The method is scalable, substrate-friendly, and well-suited for high-performance stretchable electronics.

Studies of the effect of plasma cleaning of the surface on the optical stability of monocrystal ZnGeP2 were carried out. A change in the threshold of optical breakdown was established at various parameters of plasma cleaning of the surface of crystals. When a polished ZnGeP2 surface is exposed to low-temperature plasma in an atmosphere with an electron concentration of 1014-1015 cm-3 at a voltage of 13-20 kV and a pulse repetition rate of 50-100 Hz, a 30% increase in the optical breakdown threshold of samples is observed during 500 000 pulses with ~ 40 ns duration.

This study investigates the use of radio frequency air plasma as an eco-friendly method to rapidly and reversibly tailor the surface properties of graphene oxide (GO) films. We observed a transition from hydrophilic (contact angle ∼55°) to superhydrophilic (<10°) with short plasma exposure, attributed to a synergistic combination of surface modification and etching. Spectroscopic analyses (FTIR, XPS) revealed early stage formation of carbonyl groups and reduction of hydroxyls, while longer treatments induced atomic-level etching (AFM) and structural changes (XRD). This surface engineering enhanced the dielectric properties of GO films but led to reduced aqueous stability. The elucidated interplay between plasma-induced functionalization and etching provides valuable insights for the controlled modification of GO surfaces for various applications, including advanced dielectrics.

During reactive ion etching of SiNx in fluorine-based plasmas where HF is produced through a combination of gas-phase and surface reactions, ammonium fluorosilicate (AFS) has been reported to form on the SiNx surface. However, the underlying mechanism for AFS formation and its role in SiNx etching is still unclear, particularly during etching under energetic ion bombardment. In this work, using in situ attenuated total reflection Fourier-transform infrared spectroscopy, we show that during SiNx etching with a CH2F2/Ar plasma, when the substrate was at room temperature at a bias voltage of −240 V, an etch stop occurred with the simultaneous accumulation of graphitic hydrofluorocarbon and AFS on the SiNx surface. Under nominally similar conditions in a CH2F2/Ar plasma, but with the substrate at 70 or 120 °C, no etch stop was observed along with the absence of hydrofluorocarbon and AFS. By eliminating the formation of a graphitic hydrofluorocarbon layer in a SF6/H2 plasma, also at a bias voltage of −240 V, we reveal that AFS accumulation does not necessarily lead to an etch stop, and a steady-state thickness of AFS appears on surface as a result of a balance between AFS formation due to SiNx etching and AFS decomposition due to the impingement of energetic ions and H radicals. The effect of the substrate bias voltage on the etch behavior and surface composition was also studied in CH2F2/Ar and SF6/H2 plasmas. Our results show that the AFS is likely mixed with the underlying SiNx film under energetic ion bombardment instead of being present as a well-defined uniform layer. As a result, the presence of AFS does not necessarily lead to an etch stop. AFS formed on the SiNx surface decomposed when exposed to H radicals generated in H2 plasma under self-bias. Therefore, we conclude that the H radicals can play a dual role where they facilitate AFS formation by scavenging F radicals to form HF, but can also directly remove AFS formed on the surface. Finally, the slow removal of AFS by increasing the temperature to 70 °C suggests that AFS accumulation can be controlled with the substrate temperature.

There is a high demand for plasma-resistant coatings that prevent the corrosion of the internal ceramic components of plasma etching equipment, thereby reducing particle contamination and process drift. Yttrium oxyfluoride (YOF) coatings were prepared using atmospheric plasma spraying (APS) with commercially available YOF/YF3 powder mixtures; namely YOF 3%, YOF 6%, and YOF 9%. The etching behaviour of YOF and yttrium oxide (Y2O3) coatings was investigated using an inductively coupled plasma consisting of NF3/He. X-ray photoelectron spectroscopy (XPS) showed that the YOF 6% coating had the thickest fluorinated layer. The scanning electron microscope (SEM) examination revealed that the YOF 6% coating showed exceptional resistance to erosion and generated a reduced quantity of contaminated particles in comparison to Y2O3. Consequently, it is more suitable as a protective material for the inner wall of reactors. The YOF coatings exhibit excellent stability and high resistance to erosion, indicating their appropriateness for use in the semiconductor industry.

Plasma etching treatment is an effective strategy to improve the electrocatalytic activity, but the improvement mechanism is still unclear. In this work, a nitrogen‐doped carbon nanotube‐encased iron nanoparticles (Fe@NCNT) catalyst is synthesized as the model catalyst, followed by plasma etching treatment with different parameters. The electrocatalytic activity improvement mechanism of the plasma etching treatment is revealed by combining the physicochemical characterizations and electrochemical results. As a result, highly active metal–nitrogen species introduced by nitrogen plasma etching treatment are recognized as the main contribution to the improved electrocatalytic activity, and the defects induced by plasma etching treatment also contribute to the improvement of the electrocatalytic activity. In addition, the prepared catalyst also demonstrates superior ORR activity and stability than the commercial Pt/C catalyst.

Excessive reactive oxygen species (ROS) in seminal plasma can trigger male infertility. Therefore, the development of simple and rapid ROS detection methods is urgently needed, particularly for the early self-screening of preconception couples. Herein, a gold nanobipyramid (Au NBP)-based colorimetric hydrogel for convenient and fast ROS detection is described. In the hydrogel, Au NBP is etched efficiently by ROS under the synergistic effect of Fe2+and I-, which finally causes color variations. Besides, agarose gel with the function of molecular sieve enables the separation of biomacromolecules, improving the interference resistance of the system and the stability of Au NBP. This chemical sensor can complete all the tests within 20 min, covering two detection range of 10-125 μM at relative low H2O2 concentration and 125-1000 μM at relative high H2O2 concentration, with the detection limits of 1.76 μM and 12.10 μM (S/N = 3) respectively. Furthermore, via visual observation of the color variations, it allows the initial interpretation of ROS concentration without any additional equipment. We applied this device to the detection of ROS in clinical seminal plasma samples and obtained promising results, demonstrating its potential for rapid and convenient detection in clinical applications.

For various molecular separations, mixed matrix membranes (MMMs) shown exceptional stability and great performance. Given the density disparity between the fillers and the polymer solution, the polymer matrix tends to enrich on the upper surface domain of MMMs, impairing the membrane performance. In this study, the long-distance and dynamic lowtemperature (LDDLT) plasma treatment was used to etch the asymmetric surface of ZIF-8/PEBA MMMs for improved ethanol permselective pervaporation. X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy were used to determine the crystal structure, morphology, and chemical composition of the membranes. The separation layer's thickness decreased and the amount of ZIF-8 on the separation layer raised after the LDDLT plasma etching. For separating 3 wt% ethanol aqueous solution at 40 oC, the etched ZIF-8/PEBA MMMs exhibited a good permeation flux of 1320 g·m-2 ·h-1 and a separation factor of 5.1. These results reveal that plasma etching will precisely adjust the surface of MMMs for better membrane performance.

Metallic phase 1T‐MoS2 is considered a prospective anode material for sodium‐ion batteries (SIBs) due to its remarkable electrical conductivity and unique layered structure. However, 1T‐MoS2 is thermodynamically unstable and prone to phase transition to the 2H‐MoS2 phase. Herein, self‐supporting nitrogen‐doped and carbon‐coated 1T/2H mixed‐phase MoS2 nanosheets with rich sulfur vacancies on carbon cloth (C@N‐MoS2‐p/CC) are synthesized through a hydrothermal method and Ar/NH3 radio‐frequency (RF) plasma treatment process. Density‐functional‐theory (DFT) calculations demonstrate that after Ar/NH3 RF plasma treatment, nitrogen‐doping and etching effects are realized, which combine with carbon‐coating significantly reduce the phase transition energy of 1T‐MoS2, thus triggering the phase transition and enabling the stable existence of the highly active 1T‐MoS2. As a result, the C@N‐MoS2‐p/CC exhibits outstanding sodium storage performance, with initial charge–discharge capacities of 701.0/797.0 mAh g−1 at 1 A g−1, respectively. It also demonstrates exceptional rate capabilities and ultra‐high cyclic stability, maintaining a discharge capacity of 404.2 mAh g−1 after 910 cycles at a high rate of 2 A g−1. In a full cell with Na3V2(PO4)3/CC cathode, it exhibits excellent initial charge–discharge capacities of 102.3/102.9 mAh g−1 and maintains satisfactory cycling stability after 350 cycles (86.7 mAh g−1) at 0.1 C.

Transition metal-based catalytic materials are promising pre-catalysts for oxygen evolution reaction (OER), during which the in situ reconstructed metal oxyhydroxides are real active sites. However, a majority of documented pre-catalysts exhibit sluggish reconstruction dynamics, leading to in-complete reconstruction and consequently poor OER activity. Herein, exemplified by Hoffman-type coordination polymer (NiFe-Ni PBA), plasma etching is employed to create cation-anion dual vacancies (Niv and CNv) to promote the rapid and deep reconstruction of NiFe-Ni PBA into defective NiOOH/FeOOH (P-NiOOH/FeOOH) during the activation process. Langmuir probe diagnostics and structural characterizations of NiFe-Ni PBA before and after plasma etching evidence that Niv and CNv are predominantly generated by the bombardment of high-energy ions, whereas elemental nickel will be produced when electron energy exceeds a critical threshold. Density functional theory (DFT) calculations, in situ Raman spectra, and Laviron analysis reveal that the abundant vacancies in plasma-etched NiFe-Ni PBA effectively lower the reconstruction reaction barrier and promote the accumulation of OH− ions during the reconstruction process, enabling faster reconstruction kinetics. As expected, the P-NiOOH/FeOOH exhibits enhanced OER activity with a low overpotential of 220 mV at 10 mA cm−2 and a small Tafel slope of 29.82 mV dec−1 in 1 M KOH. Magnetic test, differential electrochemical mass spectrometry measurement, and DFT calculations illustrate that the improved OER activity can be attributed to the high spin state, optimized d-band center of metal ions, rich oxygen vacancies, and more activated lattice oxygen in P-NiOOH/FeOOH. Moreover, the P-NiOOH/FeOOH also displays splendid catalytic stability up to 850 h.

This work utilizes defect engineering, heterostructure, pyridine N‐doping, and carbon supporting to enhance cobalt‐nickel selenide microspheres' performance in the oxygen electrode reaction. Specifically, microspheres mainly composed of CoNiSe2 and Co9Se8 heterojunction rich in selenium vacancies (VSe·) wrapped with nitrogen‐doped carbon nanotubes (p‐CoNiSe/NCNT@CC) are prepared by Ar/NH3 radio frequency plasma etching technique. The synthesized p‐CoNiSe/NCNT@CC shows high oxygen reduction reaction (ORR) performance (half‐wave potential (E1/2) = 0.878 V and limiting current density (JL) = 21.88 mA cm−2). The JL exceeds the 20 wt% Pt/C (19.34 mA cm−2) and the E1/2 is close to the 20 wt% Pt/C (0.881 V). It also possesses excellent oxygen evolution reaction (OER) performance (overpotential of 324 mV@10 mA cm−2), which even exceeds that of the commercial RuO2 (427 mV@10 mA cm−2). The density functional theory calculation indicates that the enhancement of ORR performance is attributed to the synergistic effect of plasma‐induced VSe· and the CoNiSe2‐Co9Se8 heterojunction. The p‐CoNiSe/NCNT@CC electrode assembled Zinc‐air batteries (ZABs) show a peak power density of 138.29 mW cm−2, outperforming the 20 wt% Pt/C+RuO2 (73.9 mW cm−2) and other recently reported catalysts. Furthermore, all‐solid‐state ZAB delivers a high peak power density of 64.83 mW cm−2 and ultra‐robust cycling stability even under bending.

Nanoporous single-crystal silicon carbide (SiC) is widely used in various applications such as protein dialysis, as a catalyst support, and in photoanodes for photoelectrochemical water splitting. However, the fabrication of nano-structured SiC is challenging owing to its extreme chemical and mechanical stability. This study demonstrates a highly-efficient, open-circuit electrolytic plasma-assisted chemical etching (EPACE) method without aggressive fluorine-containing reactants. The EPACE method enables the nano-structuring of SiC via a plasma-enveloped microtool traversing over the target material in an electrolyte bath. Through process design, EPACE readily produces a uniform nanoporous layer on a 4H-SiC wafer in KOH aqueous solution, with adjustable pore diameters in the range 40-130 nm. Plasma diagnosis by optical emission spectrometry (OES) and surface microanalysis reveal that EPACE realizes a nanoporous structure by electrolytic plasma-assisted oxidation and subsequent thermochemical reduction of an oxide. An increase in voltage or a decrease in etch gap intensifies the plasma and improves the etching efficiency. The maximum etch rate and depth reach 540 nm min-1 and 10 µm, respectively, demonstrating the significant potential of the approach as a time-saving and sustainable nanofabrication method for industrial applications. Further, the effectiveness of the fabricated SiC nanoporous structure for application in photoelectrochemical water splitting is demonstrated.

Precise monitoring of etch depth and the thickness of insulating materials, such as Silicon dioxide and silicon nitride, is critical to ensuring device performance and yield in semiconductor manufacturing. While conventional ex-situ analysis methods are accurate, they are constrained by time delays and contamination risks. To address these limitations, this study proposes a non-contact, in-situ etch depth prediction framework based on machine learning (ML) techniques. Two scenarios are explored. In the first scenario, an artificial neural network (ANN) is trained to predict average etch depth from process parameters, achieving a significantly lower mean squared error (MSE) compared to a linear baseline model. The approach is then extended to incorporate variability from repeated measurements using a Bayesian Neural Network (BNN) to capture both aleatoric and epistemic uncertainty. Coverage analysis confirms the BNN's capability to provide reliable uncertainty estimates. In the second scenario, we demonstrate the feasibility of using RGB data from digital image colorimetry (DIC) as input for etch depth prediction, achieving strong performance even in the absence of explicit process parameters. These results suggest that the integration of DIC and ML offers a viable, cost-effective alternative for real-time, in-situ, and non-invasive monitoring in plasma etching processes, contributing to enhanced process stability, and manufacturing efficiency.

No abstract available

A novel hydrophobic cellulose-based organic/inorganic nanomaterial (cellulose/TS-POSS) was prepared by oxygen plasma treatment followed by condensation reaction with TriSilanollsobutyl-Polyhedral oligomeric silsesquioxane. By careful design of cellulose film modified with TS-POSS by plasma etching, not only simply activated the hydroxyl groups on fiber surface, but also lowered the surface energy and increased the surface roughness. The surface morphology, chemical structure, thermal properties, and hydrophobic properties of cellulose/TS-POSS materials were systematically investigated by FTIR, SEM, AFM, CA, and TGA, respectively. The experimental results showed that the static water contact angle of cellulose/TS-POSS was 152.9°, demonstrating super-hydrophobicity. The results indicated that the TS-POSS were observed uniformly dispersed in the cellulose at the nanometer scale to form nanostructures, successful bonding to cellulose through condensation reaction. This process developed in this paper provided new solutions and approximations for the facile fabrication of sustainable cellulose-based hydrophobic materials.

We investigated the etching behavior of silicon oxide (SiO x ) and silicon nitride (SiN x ) in narrow-gap, high-pressure (3.3 kPa) hydrogen (H2) plasma under various etching conditions. Maximum etching rates of 940 and 240 nm min−1 for SiO x and SiN x , respectively, were obtained by optimizing the H2 gas flow rate. The dependence of the etching rate on gas flow rate implied that effective elimination of etching products is important for achieving high etching rates because it prevents redeposition. The sample surfaces, especially the oxide surfaces, were roughened and contained numerous asperities after etching. Etching rates of both SiO x and SiN x decreased as the temperature was raised. This suggests that atomic H adsorption, rather than H-ion bombardment, is an important step in the etching process. X-ray photoelectron spectroscopy revealed that the etched nitride surface was enriched in silicon (Si), suggesting that the rate-limiting process in high-pressure H2 plasma etching is Si etching rather than nitrogen abstraction. The etching rate of SiO x was three times higher than that of SiN x despite the higher stability of Si–O bonds than Si–N ones. One reason for the etching difference may be the difference between the bond densities of SiO x and SiN x . This study presents a relatively non-toxic, low-cost, and eco-friendly dry etching process for Si-based dielectrics using only H2 gas in comparison with the conventional F-based plasma etching methods.

A method of increasing the silicon plasma etching temperature regime stability to depths exceeding 100 μm is proposed. The influence of the substrate temperature gradient on the etching rate unevenness, the inclination angle of the side walls, undercut under the mask, the mask structural defects and the etching profile bottom roughness (the "black" silicon effect) has been investigated. It was revealed that the programmed segmentation of the process into the etching and cooling stages ("interval" etching method) allows keeping the substrate temperature at a level below 100°C. This eliminates the structural defects occurrence in the photoresist layers. With "continuous" etching, the substrate temperature can rise above 145°C, resulting to cracks in the photoresist layer and multiple tears. The "interval" method proposed in this work made it possible to develop the silicon through etching process with an etching rate unevenness across the wafer of less than ± 3%, a wall inclination angle of from 88° to 90°, and almost complete absence of lateral undercut under the mask.

Atomic layer etching (ALE) has emerged as a promising technique for the precise and controlled removal of materials in nanoscale devices. ALE processes have gained significant attention due to their ability to achieve high material selectivity, etch uniformity, and atomic-scale resolution. This article provides a perspective of the important role of plasma in ALE including thermal ALE for nanometer-scale device manufacturing. Advantages as well as challenges of ALE are discussed in contrast to classic reactive ion etching. A tally-up of known plasma-based ALE processes is listed, and novel thermal ALE processes are described that are based on the so-called ligand addition mechanism. We explain the potential of using plasma for increasing wafer throughput in a manufacturing environment, its use when it comes to anisotropy tuning, the benefits in enabling a wider range of pre-cursors in thermal ALE, and the advantages it may bring for thermal ALE of crystalline materials. The benefits and challenges of different plasma sources in ALE are discussed, and an outlook for future development is provided. Finally, applications of plasma for productivity reasons such as particle avoidance and process stability are outlined.

Electrocatalysts with strong stability and high electrocatalytic activity have received increasing interest for oxygen reduction reactions (ORRs) in the cathodes of energy storage and conversion devices, such as fuel cells and metal-air batteries. However, there are still several bottleneck problems concerning stability, efficiency, and cost, which prevent the development of ORR catalysts. Herein, we prepared bimetal FeCo alloy nanoparticles wrapped in Nitrogen (N)-doped graphitic carbon, using Co-Fe Prussian blue analogs (Co3[Fe(CN)6]2, Co-Fe PBA) by the microwave-assisted carbon bath method (MW-CBM) as a precursor, followed by dielectric barrier discharge (DBD) plasma treatment. This novel preparation strategy not only possessed a fast synthesis rate by MW-CBM, but also caused an increase in defect sites by DBD plasma treatment. It is believed that the co-existence of Fe/Co-N sites, rich active sites, core-shell structure, and FeCo alloys could jointly enhance the catalytic activity of ORRs. The obtained catalyst exhibited a positive half-wave potential of 0.88 V vs. reversible hydrogen electrode (RHE) and an onset potential of 0.95 V vs. RHE for ORRs. The catalyst showed a higher selectivity and long-term stability than Pt/C towards ORR in alkaline media.

The micro-capillary condensation of a new high boiling point organic reagent (HBPO), is studied in a periodic mesoporous oxide (PMO) with ∼34 % porosity and k-value ∼2.3. At a partial pressure of 3 mT, the onset of micro-capillary condensation occurs around +20 °C and the low-k matrix is filled at −20 °C. The condensed phase shows high stability from −50 < T ≤−35 °C, and persists in the pores when the low-k is exposed to a SF6-based plasma discharge. The etching properties of a SF6-based 150W-biased plasma discharge, using as additive this new HBPO gas, shows that negligible damage can be achieved at −50 °C, with acceptable etch rates. The evolution of the damage depth as a function of time was studied without bias and indicates that Si-CH3 loss occurs principally through Si-C dissociation by VUV photons.

The implementation of through-silicon vias for high-performance semiconductor devices requires a reliable fabrication process that can achieve high aspect ratio (HAR) silicon nanoholes (Si NHs). Currently, Si NHs are primarily fabricated via plasma-based dry etching, which has technical limitations, such as necking and bowing. Metal-assisted chemical etching (MaCE) is an alternative Si NH fabrication method that utilizes wet chemistry catalyzed by metals. However, the formation of HAR Si NHs is challenging because of the unstable motion of metal catalysts during MaCE. Herein, we introduce electric-field-incorporated MaCE (EMaCE) to improve the anisotropic etching stability of metal catalysts and achieve the formation of Si NHs. The etch straightness gradually improved with increasing electric field intensity while the etch rate remained nearly constant. We optimized the etchant concentration and etch time to increase the etch rate, and thus, fabricated an ultra-HAR (38:1) Si NHs array via EMaCE.

Using two highly efficient inhibitors, one for silicon and one for SiO2 and SiN it is possible by varying the hydrogenperoxide concentration to achieve tuneable formulated chemistry concerning selectivity. So, the same formulation can be used for the selective etching of SiGe25 vs. Si like for GAA applications as well as for the selective etching of SiGe40 vs. SiGe20 like for CFET applications.

BACKGROUND Rational engineering of multienzyme system architecture is essential for achieving high-performance multi-enzyme cascade catalysis in sensing applications. In this context, the initiation step of the cascade reaction pathway plays a pivotal role in enhancing catalytic efficiency. CoFe Prussian blue analogue (CoFePBA), a dual-metal organic framework, is an ideal template for multi-enzyme design, leveraging its diverse dual-metal ion functionalities and synergistic effects. Defect engineering approaches enable the fine-tuning of catalytic properties, optimizing electron transfer and promoting reaction intermediates. Therefore, the rational design of the multienzyme system structure is critical for efficient cascade catalysis. RESULTS In this study, we utilized deep eutectic solvents (DES) to selectively induce Co defects in CoFePBA (CoFePBA-DES) under mild conditions, providing more active sites and enhancing the Co2+/Co3+ ratio, significantly boosting the initial step of the cascade reaction. This then triggers the three-enzyme cascade reaction system-oxidase (OXD), superoxide dismutase (SOD), and peroxidase (POD)-which facilitates the conversion of products from O2 to O2•- to endogenous H2O2, achieving a two-fold increase in its yield and subsequently to OH• in a sequential reaction, demonstrating excellent multi-enzyme cascade catalytic activity. Utilizing the inhibitory effect of glutathione (GSH) on multi-enzyme cascade catalytic activity, we designed a highly efficient and rapid colorimetric sensor for the sensitive detection of GSH, with a detection range of 0.5-160 μM and a detection limit of 0.15 μM. SIGNIFICANCE Compared to traditional etching techniques, DES-based methods offer superior selectivity, lower toxicity, and better structural preservation of the MOF framework, making them a promising tool for controlled defect engineering. By selectively creating defects, the initial steps of the cascade reaction are activated, resulting in a significant enhancement of catalytic activity. This approach provides a viable pathway for the preparation of high-performance dual-metal catalysts for cascade reaction catalysts and sensing applications.

The Sn‐Beta zeolite is commonly known as a unique Lewis acid catalyst, however, usually suffers from the drawback of diffusion limitation within zeolitic micropores. To address these issues, the present work reports a facile fluoride etching approach for the synthesis of hierarchical Sn‐Beta zeolites by tuning chemical equilibrium of HF and NH4F mixed solutions. It was found that the etching of HF solution alone only extracts Sn species in the Sn‐Beta framework while adding NH4F into HF solution shifts the chemical equilibria to produce more reactive HF2− for Si, thereby achieving unbiases selective extraction of Si and Sn from *BEA framework. The obtained hierarchical Sn‐Beta zeolite possessed excellent catalytic activity in Baeyer‐Villiger oxidation of bulky 2‐adamantanone with aqueous hydrogen peroxide. Structure‐performance relationship revealed that the Lewis acid site and the pore structure are two crucial factors determining the catalytic activity. The former was identified as a catalytic active center while the latter increase the accessibility to active sites in microporous Sn‐Beta zeolites by forming hierarchical porosity. Therefore, the sample obtained after optimizing the conditions of NH4F‐ HF mixed solutions presented a remarkably enhanced catalytic oxidation activity for bulky molecules.

Structural coloration, originating from nanoscale interactions of light with engineered surfaces, delivers tunable color features and application potential in anti-counterfeiting compared to conventional dye-based methods. In this study, a fabrication strategy for structural color surfaces is presented by integrating ultra-precision mechanical patterning with selective wet etching of Al/Cu multilayer thin films. By precisely adjusting the cutting load, the number of exposed Cu layers is controlled, enabling the formation of single-layer lamellar (SLL) and double-layer lamellar (DLL) nanostructures. Subsequent wet etching selectively removed the Cu layers, further refining the lamellar geometry. Optical characterization revealed that DLL structures exhibited vivid, angle-independent blue coloration, while SLL structures showed angle-dependent spectral variations. Chromaticity analysis quantitatively confirmed the correlation between the lamellar architecture and the resulting optical behavior. Additionally, directional structural color patterns with orientation-dependent visibility are successfully demonstrated, which highlights their potential for multi-level optical security applications. To further improve durability, conformal Al2O3 encapsulation by atomic layer deposition is applied, preserving the optical response while enhancing environmental stability. This work offers a practical and scalable approach to customizable structural color devices, supporting their use in nanophotonic applications and advanced anti-counterfeiting technologies.

Selective oxidative etching is one of the most effective ways to prepare hollow nanostructures and nanocrystals with specific exposed facets. The mechanism of selective etching in noble metal nanostructures mainly relies on the different reactivity of metal components and the distinct surface energy of multimetallic nanostructures. Recently, phase engineering of nanomaterials (PEN) offers new opportunities for the preparation of unique heterostructures, including heterophase nanostructures. However, the synthesis of hollow multimetallic nanostructures based on crystal‐phase‐selective etching has been rarely studied. Here, a crystal‐phase‐selective etching method is reported to selectively etch the unconventional 4H and 2H phases in the heterophase Au nanostructures. Due to the coating of Pt‐based alloy and the crystal‐phase‐selective etching of 4H‐Au in 4H/face‐centered cubic (fcc) Au nanowires, the well‐defined ladder‐like Au@PtAg nanoframes are prepared. In addition, the 2H‐Au in the fcc‐2H‐fcc Au nanorods and 2H/fcc Au nanosheets can also be selectively etched using the same method. As a proof‐of‐concept application, the ladder‐like Au@PtAg nanoframes are used for the electrocatalytic hydrogen evolution reaction (HER) in acidic media, showing excellent performance that is comparable to the commercial Pt/C catalyst.

A simulation model for selective molecular gas etching in nanostructures has been described in Paper I [Z. Zajo et al. J. Vac. Sci. Technol. A 43, 013006 (2025)], in which the transport of molecules was modeled as Knudsen diffusion in the free-molecular flow regime and the surface reactions were modeled using (i) a simple linear model and (ii) a Langmuir adsorption based model. In this paper, we complete experiments on etching of stacked SiGe-Si structures by molecular F2 and compare the results of experiments and the predictions from the model mentioned above. The results of our investigation show that the transport of F2 in the nanostructures is in the nearly total re-emission regime for the range of process parameters and length scales involved in our experiments and that only a very small fraction of the incoming F2 flux reacts with SiGe. This is evidenced by the small values of estimated sticking coefficients on SiGe (∼10−6–10−3) from the linear model as well as the small values of the reaction rate constant on SiGe relative to the F2 flux on an open surface, k2/J (∼10−7–10−4) with the exact value being dependent on Ge% and the temperature at which the etching is performed. This enables the achievement of uniform etch rates across all layers in highly stacked nanostructures as required in the fabrication of gate-all-around nanotransistors. We also estimate the surface reaction rate constants as well as the activation energies as a function of Ge% for SiGe etching by F2, and the results are consistent with the observed Ge composition dependence of etch selectivity of SiGe over Si.

The need for precise control of nanoscale geometric features poses a challenge in manufacturing advanced gate-all-around nanotransistors. The high material selectivity required in fabricating these transistors makes thermal gas etching much more appealing in comparison to liquid phase and plasma-based etching techniques. The selective thermal etching by F2 of silicon–germanium (SiGe) stacks comprised of alternating layers of silicon (Si) and SiGe is explored in this context for semiconductor manufacturing applications. We propose and develop computer simulations as a tool to predict the etch profile evolution over time in such an etching process. The tool is based on a mathematical model that considers the transport processes and surface interactions involved in the gas phase etching process—which at the nanoscale is primarily Knudsen diffusion in the free molecular flow regime. Thus, the transport model is formulated as a boundary integral equation, which takes into account the direct flux of etchant molecules that any given point on the exposed surface receives from the bulk gas phase as well as the re-emission flux from other parts of the structure itself. We compared the applicability of two different surface reaction models—a model where the local etch rate is linear in the flux at a point and a Langmuir adsorption/reaction model—to connect the net flux received at a point on the surface to the local etch rate. This paper precedes Paper II of this series, which describes the experimental methods and comparison with model predictions of F2 etching in high aspect ratio Si–SiGe stacked nanostructures.

Atomic-scale smooth surfaces of single-crystal silicon (Si) are indispensable for cutting-edge applications, such as semiconductor chips, quantum devices, and X-ray optics. Here, we vary the CF4/O2 reactant gas ratio to tune the etching mode from isotropic and orientation-selective etching to atom-selective etching in an atmospheric inductively coupled plasma (ICP). At low CF4/O2 ratios, the diffusion of the etching species dominates, resulting in isotropic etching. By contrast, the kinetics of ICP etching becomes dominant upon increasing the CF4/O2 ratio to between 1:1 and 2:1, inducing orientation-selective etching. Notably, CF4/O2 ratios above 2:1 result in atom-selective etching, whereby atoms around rough surface sites can be selectively removed. The atom-selective etching mode was used to achieve an atomically smooth surface with a Sa roughness of 0.14 nm. The results of this study demonstrate that atom-selective etching is an efficient and effective approach for manufacturing Si atomic surfaces.

Ag nanoparticles have garnered significant attention for their excellent plasmonic properties and potential use as plasmonic cavities, primarily because of their intrinsically low ohmic losses and optical properties in the visible range. These are particularly crucial in systems involving quantum dots that absorb light at low wavelengths, where the need for a high threshold energy of interband transitions necessitates the incorporation of Ag nanostructures. However, the synthesis of Ag nanoparticles still encounters challenges in achieving structural uniformity and monodispersity, along with chemical stability, consequentially inducing inconsistent and poorly reliable optical responses. Here, we present a two-step approach for synthesizing highly uniform spherical Ag nanoparticles involving depletion-induced flocculation and Cu(II)-mediated oxidative etching. We found that the selective flocculation of multitwinned Ag nanocrystals significantly enhances the uniformity of the resulting Ag nanostructures, leaving behind only single-crystalline and single-twinned nanostructures. Subsequent oxidative etching, in which cupric ions are directly involved in the reaction, was designed based on Pourbaix diagrams to proceed following thermodynamically favorable states and circumvent the generation of reactive chemical species such as H2O2. This leads to perfectly spherical shapes of final Ag nanoparticles with a synthetic yield of 99.5% and additionally reduces the overall reaction time. Furthermore, we explore the potential applications of these monodisperse Ag nanospheres as uniform plasmonic cavities. The fabricated Ag nanosphere films uniformly enhanced the photoluminescence of InP/ZnSe/ZnS quantum dots, showcasing their capabilities in exhibiting consistent plasmonic responses across a large area.

No abstract available

The highly programmable and responsive molecular recognition properties of DNA provide unparalleled opportunities for fabricating dynamic nanostructures capable of structural transformation in response to various external stimuli. However, they typically operate in tightly controlled environments because certain conditions (ionic strength, pH, temperature, etc.) must be met for DNA duplex formation. In this study, we adopted site-specific enzymatic ligation and DNA-based layer-by-layer thin film fabrication to build shape-morphing DNA-linked nanoparticle films operational in a broad range of environments. The ligated films remained intact in unusual conditions such as pure water and high temperature causing dissociation of DNA duplexes and showed predictable and reversible shape morphing in response to various environmental changes and DNA exchange reactions. Furthermore, domain-selective ligation combined with photoinduced interlayer mixing allowed for the fabrication of unusual edge-sealed double-layered films through midlayer etching, which is difficult to realize by other methods.

Porous alloy nanomaterials are important for applications in catalysis, sensing, and actuation. Chemical and electrochemical etching are two methods to form porous nanostructures by dealloying bimetallic nanoparticles (NPs). However, it is not clear how the NPs evolve during these etching processes. Insight into the morphological and compositional transformations of the NPs during the etching is critical to understanding the nanoscale details of the dealloying process. Here, using in situ liquid phase transmission electron microscopy, the structural evolution of individual AuAg alloy NPs is tracked during both chemical and electrochemical etching of their Ag component. The observations show that the electrochemical etching produces NPs with more uniform pore sizes than the chemical etching and enables tuning the NPs porosity by modulating the electrochemical potential. The results show that at the initial stages of both etching methods, Au-rich passivation layer forms on the surface of the NPs, which is critical in preserving the NP's porous shell as pores form underneath this layer during the etching. These findings describing the selective etching and dealloying of AuAg NPs provide a critical insight needed to control the morphology and composition of porous multimetallic NPs, and paves the way for synthesizing nanomaterials with tailored chemical and physical properties for various applications.

Smooth, high-aspect-ratio directional structures in oxides such as silica (SiO2) are essential for efficient diffraction in optical and nanophotonic devices. Achieving these features requires high pattern-transfer fidelity, anisotropic profiles, smooth surfaces, and uniform processing suitable for scalable, high-throughput production. We present a simplified model describing SiO2 etching dynamics in pure sulfur hexafluoride (SF6) plasmas, supported by experimental evidence from fabricated sub-300 nm structures via reactive ion etching using a chromium (Cr) hard mask. The etch rate exhibits a pronounced etch rate maximum of around 5 mTorr, which seems to be correlated with Paschen behavior. The influence of the reactor wall, electrode, and mask materials is examined, with an emphasis on mechanisms for the self-formation and suppression of nanoroughness via a cyclic etch process that allows for unprecedented selectivity. Furthermore, we will discuss the appearance of abnormalities such as faceting, footing, and microtrenching and how to suppress them. The developed process enables repeatable and scalable transfer of nanoscale resist patterns into dielectric materials. It results in anisotropic and highly selective etching with respect to Cr, without preconditioning or cleaning the etch tool. The method provides a gas-efficient alternative to conventional fluorocarbon-based etching processes.

The size and shape of semiconductor nanocrystals govern their optical and electronic properties. Liquid cell transmission electron microscopy (LCTEM) is an emerging tool that can directly visualize nanoscale chemical transformations and therefore inform the precise synthesis of nanostructures with desired functions. However, it remains difficult to controllably investigate the reactions of semiconductor nanocrystals with LCTEM, because of the highly reactive environment formed by radiolysis of liquid. Here, we harness the radiolysis processes and report the single-particle etching trajectories of prototypical semiconductor nanomaterials with well-defined crystalline facets. Lead selenide nanocubes represent an isotropic structure that retains the cubic shape during etching via a layer-by-layer mechanism. The anisotropic arrow-shaped cadmium selenide nanorods have polar facets terminated by either cadmium or selenium atoms, and the transformation trajectory is driven by etching the selenium-terminated facets. LCTEM trajectories reveal how nanoscale shape transformations of semiconductors are governed by the reactivity of specific facets in liquid environments.

Elucidating the interactions between halide ions and bimetallic oxides can help understand their influences on the physicochemical properties of bimetallic oxides and ultimately lead to better performance, but this has not yet been explored. We report here the first study of the interaction of halide ions with two phase-pure bimetallic Ag-Cu oxides, Ag2Cu2O3 and Ag2Cu2O4, which have different chemical valences of Ag and Cu atoms. We found that halide ions have an aggressive etching effect on both bimetallic oxides, leading to a dramatic evolution of crystal structures and morphology. Halide ions act like "nano-carving knives", selectively etching out silver atoms to form silver halides and leaving a porous CuO skeleton. We revealed that Ag2Cu2O4 underwent a redox reaction with iodide ions (I-) to produce additional I3- in the solution, which was not observed in Ag2Cu2O3. Interestingly, according to the revealed interactions, both bimetallic oxides are confirmed as superior adsorbents to remove I- from wastewater in terms of a record-high uptake capacity, fast adsorption kinetics, and excellent selectivity for I-. Furthermore, such a halide etching can be turned into a powerful synthetic strategy. The out-etched silver halides were dissolved to give robust porous CuO nanostructures, which are proved to be excellent glucose-sensing electrodes with high sensitivity, excellent anti-interference, and stability, showing great application potential. This work contributes to improving the understanding of the mechanisms of halide ion-metal oxide interactions and ultimately to innovative applications.

Fabrication of nanostructures on sapphire surfaces can enable unique applications in nanophotonics, optoelectronics, and functional transparent ceramics. However, the high chemical stability and mechanical hardness of sapphire make the fabrication of high density, high aspect ratio structures in sapphire challenging. In this study, we propose the use of optical emission spectroscopy (OES) to investigate the sapphire etching mechanism and for endpoint detection. The proposed process employs nanopillars composed of polymer and polysilicon as an etch mask, which allows the fabrication of large-area sapphire nanostructures. The results show that one can identify the emission wavelengths of key elements Al, O, Br, Cl, and H using squared loadings of the primary principal component obtained from principal component analysis of OES readings without the need of domain knowledge or user experience. By further examining the OES signal of Al and O at 395.6 nm, an empirical first-order model can be used to find a predicted endpoint at around 170 s, indicating the moment when the mask is completely removed, and the sapphire substrate is fully exposed. The fabrication results show that the highest aspect ratio of sapphire nanostructures that can be achieved is 2.07, with a width of 242 nm and a height of 500 nm. The demonstrated fabrication approach can create high sapphire nanostructures without using a metal mask to enhance the sapphire etch selectivity.

The development of multifunctional biomimetic nanozymes with high catalytic activity and sensitive response is rapidly advancing. The hollow nanostructures, including metal hydroxides, metal-organic frameworks, and metallic oxides, possess excellent loading capacity and a high surface area-to-mass ratio. This characteristic allows for the exposure of more active sites and reaction channels, resulting in enhanced catalytic activity of nanozymes. In this work, based on the coordinating etching principle, a facile template-assisted strategy for synthesizing Fe(OH)3 nanocages by using Cu2O nanocubes as the precursors was proposed. The unique three-dimensional structure of Fe(OH)3 nanocages endows it with excellent catalytic activity. Herein, in the light of Fe(OH)3-induced biomimetic nanozyme catalyzed reactions, a self-tuning dual-mode fluorescence and colorimetric immunoassay was successfully constructed for ochratoxin A (OTA) detection. For the colorimetric signal, 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) can be oxidized by Fe(OH)3 nanocages to form a color response that can be preliminarily identified by the human eye. For the fluorescence signal, the fluorescence intensity of 4-chloro-1-naphthol (4-CN) can be quantitatively quenched by the valence transition of Ferric ion in Fe(OH)3 nanocages. Due to the significant self-calibration, the performance of the self-tuning strategy for OTA detection was substantially enhanced. Under the optimized conditions, the developed dual-mode platform accomplishes a wide range of 1 ng/L to 5 μg/L with a detection limit of 0.68 ng/L (S/N = 3). This work not only develops a facile strategy for the synthesis of highly active peroxidase-like nanozyme but also achieves promising sensing platform for OTA detection in actual samples.

The distribution of oxygen and aluminum vacancies across the hemispherical barrier oxide layer (BOL) of nanoporous anodic alumina (NAA) relies intrinsically on the electric field-driven flow of electrolytic species and the incorporation of electrolyte impurities during the growth of anodic oxide through anodization. This phenomenon provides new opportunities to engineer BOL's inherited ionic current rectification (ICR) fingerprints. NAA's characteristic ICR signals are associated with the space charge density gradient across BOL and electric field-induced ion migration through hopping from vacancy to vacancy. In this study, we engineer the intrinsic space charge density gradient of the BOL of NAA under a range of anodizing potentials in hard and mild anodization regimes. Real-time characterization of the ICR fingerprints of NAA during selective etching of the BOL makes it possible to unravel the distribution pattern of vacancies through rectification signals as a function of etching direction and time. Our analysis demonstrates that the space charge density gradient varies across the BOL of NAA, where the magnitude and distribution of the space charge density gradient are revealed to be critically determined by anodizing the electrolyte, regime, and potential. This study provides a comprehensive understanding of the engineering of ion transport behavior across blind-hole NAA membranes by tuning the distribution of defects across BOL through anodization conditions. This method has the potential to be harnessed for developing nanofluidic devices with tailored ionic rectification properties for energy generation and storage and sensing applications.

Nanostructures formed in silicon form an important class of structures that span a broad spectrum of application areas. Of these, columnar structures of silicon featuring tiplike apexes have their own niche applications. The ability to afford shape tunability for these structures further enhances their application potential. In this paper, we present our findings on the large area fabrication of silicon nanotips defined through microsphere lithography and shape tuned through a combination of different reactive ion etching (RIE) techniques. The self-sharpening mechanism of the tips when using nonplanar etch masks (microspheres) under anisotropic etching conditions is elucidated. We further show that depending on the manner of etching (continuous versus discrete multistep etch), identical anisotropic etching recipes produce vastly different tip morphologies. Hourglass-shaped silicon tips were obtained when silicon was subjected to anisotropic followed by isotropic etching conditions. Sharp silicon tips with tip apex radii on the order of 2 nm have been successfully realized when the RIE shape tuned tips were subjected to a series of oxidative sharpening steps.

In the current work, the chemical etching process and hydrothermal method were used to create bio‐inspired superhydrophobic fluorine‐free tin oxide nanostructures on copper plates. Taguchi's experimental design was also used in investigating coating wettability characteristics based on fabrication parameters. Statistical analysis results demonstrated that the optimal superhydrophobic sample with a water contact angle of 163.40° ± 1.42° and contact angle hysteresis of 3.00° ± 0.80° could be fabricated under the following conditions: sodium hydroxide (2.00 M) as an etching solution, urea‐to‐tin chloride ratio 2.5:1, and 2.00 h reaction times. The effects of each synthesis parameter on the obtained sample's superhydrophobicity were evaluated through multiple one‐variable‐at‐a‐time experiments. Testing the chemical stability of the optimal sample revealed that it was more resistant to deterioration in an alkaline environment (8–10) than in an acidic environment (4–6). The resulting superhydrophobic sample was analyzed by a delay test for water droplets freezing on its surface to determine whether ice formed and accumulated. The created bio‐inspired honeycomb‐like nanocoating demonstrated exceptional mechanical robustness and good anti‐icing performance after 10 consecutive icing cycles. These results indicated that superhydrophobic coatings could be easily and economically produced without using fluoropolymers and silanes on aluminum substrates.

No abstract available

Two-dimensional (2D) materials provide a great opportunity for fabricating ideal membranes with ultrathin thickness for high-throughput separation. Graphene oxide (GO), owing to its hydrophilicity and functionality, has been extensively studied for membrane applications. However, fabrication of single-layered GO-based membranes utilizing structural defects for molecular permeation is still a great challenge. Optimization of the deposition methodology of GO flakes could offer a potential solution for fabricating desired nominal single-layered (NSL) membranes that can offer a dominant and controllable flow through structural defects of GO. In this study, a sequential coating methodology was adopted for depositing a NSL GO membrane, which is expected to have no or minimum stacking of GO flakes and thus ensure GO's structural defects as the major transport pathway. We have demonstrated effective rejection of different model proteins (bovine serum albumin (BSA), lysozyme, and immunoglobulin G (IgG)) by tuning the structural defect size via oxygen plasma etching. By generating appropriate structural defects, similar-sized proteins (myoglobin and lysozyme; molecular weight ratio (MWR): ∼1.14) were effectively separated with a separation factor of ∼6 and purity of 92%. These findings may provide new opportunities of using GO flakes for fabricating NSL membranes with tunable pores for applications in the biotechnology industry.

No abstract available

Engineering coordination compounds, e.g., prussian blue (PB) and its analogues (PBAs), with designable complex nanostructures via chemical etching holds great opportunities for improving energy storage performances by adjusting topological geometry, selectively exposing active sites, tuning electronic properties and enhancing accessible surface area. Unfortunately, it remains ambiguous particularly on site-selective and anisotropic etching behaviors. Herein, for the first time, we propose that two distinct regions are formed inside NiCo PBA (NCP) cubes due to the competition between classical ion-by-ion crystallization and non-classical crystallization based on aggregation. Such a unique structure ultimately determines not only the etching position but also the anisotropic pathway by selectively exposing unprotected Ni sites. According to this principle, complex PBA architectures, including nanocages, open nanocubes (constructed by six cones sharing the same apex), nanocones, and chamfer nanocubes can be intentionally obtained. After thermal annealing, NCP nanocones are converted to morning glory-like porous architectures composed of NiO/NiCo2O4 heterostructures with a mean particle size of 5 nm, which show improved rate performance and cycling stability.

Flexible electrodes fabricated through cost-effective thick-film strategies are important for developing electrochemical devices, such as sensors. Properly engineered nanocomposite electrodes can enhance the electrochemically active surface area, facilitate mass and charge transport, and allow for tailored surface chemistry and structure. Although great efforts have been devoted to developing porous nanocomposite electrodes, a facile method to achieve screen-printed porous nanocomposite electrodes in the form of flexible electrodes with tunable electrochemical performance has been overlooked. This article introduces a strategy for fabricating flexible porous electrodes using screen printing and electrochemical surface treatments, resulting in enhanced surface chemistry and electrochemical properties. By applying selective etching and anodization, the electrode’s surface area increases by 214% compared to a nontreated electrode, enabling programmable sensitivity to specific molecules. The engineered electrode improves the hydroquinone-to-salicylic acid detection ratio from less than 1 to over 10, allowing selective detection of neutral and positively charged molecules while rendering the electrode inactive for negatively charged species. This flexible sensor can be integrated into a wearable glove for rapid analysis and has also been successfully implemented in a second-generation glucose biosensor. This approach holds significant potential for advancing surface electrochemistry, offering new possibilities for tailoring electrode surfaces for diverse analytical applications.

Cardiovascular diseases are a pre-eminent global cause of mortality in the modern world. Typically, surgical intervention with implantable medical devices such as cardiovascular stents is deployed to reinstate unobstructed blood flow. Unfortunately, existing stent materials frequently induce restenosis and thrombosis, necessitating the development of superior biomaterials. These biomaterials should inhibit platelet adhesion (mitigating stent-induced thrombosis) and smooth muscle cell proliferation (minimizing restenosis) while enhancing endothelial cell proliferation at the same time. To optimize the surface properties of Ti6Al4V medical implants, we investigated two surface treatment procedures: gaseous plasma treatment and hydrothermal treatment. We analyzed these modified surfaces through scanning electron microscopy (SEM), water contact angle analysis (WCA), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) analysis. Additionally, we assessed in vitro biological responses, including platelet adhesion and activation, as well as endothelial and smooth muscle cell proliferation. Herein, we report the influence of pre/post oxygen plasma treatment on titanium oxide layer formation via a hydrothermal technique. Our results indicate that alterations in the titanium oxide layer and surface nanotopography significantly influence cell interactions. This work offers promising insights into designing multifunctional biomaterial surfaces that selectively promote specific cell types’ proliferation—which is a crucial advancement in next-generation vascular implants.

Tuning the spin state of the FeN4 site to optimize its adsorption strength for the ORR intermediates remains a challenge. Herein, we demonstrate that a defect-engineered carbon material via CO2 selective etching can effectively raise the spin state of Fe center of FePc/NC-CO2-900 compared to that of FePc. It shows a higher half-wave potential of 0.90 V and kinetic current density of 110.6 mA cm-2 at 0.8 V than those of Pt/C and FePc. Theoretical calculations reveal that FePc with increased spin state in FePc/NC-CO2-900 facilitates the activation of oxygen molecules compared to the FePc catalyst.

Nano-objects are favored structures for applications such as catalysis and sensing. Although they already provide a large surface-to-volume ratio, this ratio can be further increased by shape-selective plating of the nanostructure surfaces. This process combines the conformity of autocatalytic deposition with the defined nucleation and growth characteristics of colloidal nanoparticle syntheses. However, many aspects of such reactions are still not fully understood. In this study, we investigate in detail the growth of spiky nickel nanotubes in polycarbonate template membranes. One distinctive feature of our synthesis is the simultaneous growth of nanospikes on both the inside and outside of nanotubes while the tubes are still embedded in the polymer. This is achieved by combining the plating process with locally enhanced in situ etching of the poylmer template, for which we propose a theory. Electron microscopy investigations reveal twinning defects as the driving force for the growth of crystalline nanospikes. Deposit crystallinity is ensured by the reducing agent hydrazine. Iminodiacetic acid is not only used as a complexing agent during synthesis but apparently also acts as a capping agent and limits random nucleation on the spike facets. Finally, we apply our synthesis to templates with interconnected pores to obtain free-standing spiky nickel nanotube networks, demonstrating its ability to homogeneously coat substrates with extended inner surfaces and to operate in nanoscale confinement.

We report a visual detection of Cr(VI) ions using silver-coated gold nanorods (AuNR@Ag) as sensing probes. Au NRs were prepared by a seed-mediated growth process and AuNR@Ag nanostructures were synthesized by growing Ag nanoshells on Au NRs. Successful coating of Ag nanoshells on the surface of Au NRs was demonstrated with TEM, EDS, and UV–vis spectrometer. By increasing the overall amount of the deposited Ag on Au NRs, the localized surface plasmon resonance (LSPR) band was significantly blue-shifted, which allowed tuning across the visible spectrum. The sensing mechanism relies on the redox reaction between Cr(VI) ions and Ag nanoshells on Au NRs. As the concentration of Cr(VI) ions increased, more significant red-shift of the longitudinal peak and intensity decrease of the transverse peak could be observed using UV–vis spectrometer. Several parameters such as concentration of CTAB, thickness of the Ag nanoshells and pH of the sample were carefully optimized to determine Cr(VI) ions. Under optimized condition, this method showed a low detection limit of 0.4 μM and high selectivity towards Cr(VI) over other metal ions, and the detection range of Cr(VI) was tuned by controlling thickness of the Ag nanoshells. From multiple evaluations in real sample, it is clear that this method is a promising Cr(VI) ion colorimetric sensor with rapid, sensitive, and selective sensing ability.

Green hydrogen, produced via renewable‐energy‐driven water electrolysis, is among the most promising new energy carriers. Ru is a potential catalyst for this purpose; however, its strong hydrogen binding strength results in poor reaction kinetics, limiting its application potential. Creating a new Ru structure by introducing a second element is crucial for optimizing its catalytic performance. However, only a few studies have explored this approach, leaving the understanding of how chemical composition influences Ru's structure and catalytic activity elusive. Here, a systematic study is reported on Si decoration of Ru, achieving a tunable local environment around Ru and optimized reaction kinetics. By constructing a Ru‐SiOx interleaved Turing‐patterned structure, the ratio of Si coordinated to Ru is tuned by well‐designed selective etching. With increasing Si content, the H‐binding strength on the Ru center is progressively weakened, resulting in a V‐shaped trend in hydrogen production activity. The optimized sample exhibits a low overpotential of 21 mV at 10 mA cm−2 in alkaline solution, along with a Tafel slope of 40 mV dec−1, surpassing the performance of commercial Pt/C. This study establishes a valuable framework for optimizing the surface properties and catalytic activity of noble metals.

Although grain boundaries (GBs) in two-dimensional (2D) materials have been extensively observed and characterized, their formation mechanism still remains unexplained. Here a general model has reported to elucidate the mechanism of formation of GBs during 2D materials growth. Based on our model, a general method is put forward to synthesize twinned 2D materials on a liquid substrate. Using graphene growth on liquid Cu surface as an example, the growth of twinned graphene has been demonstrated successfully, in which all the GBs are ultra-long straight twin boundaries. Furthermore, well-defined twin boundaries (TBs) are found in graphene that can be selectively etched by hydrogen gas due to the preferential adsorption of hydrogen atoms at high-energy twins. This study thus reveals the formation mechanism of GBs in 2D materials during growth and paves the way to grow various 2D nanostructures with controlled GBs.

No abstract available

No abstract available

Wet etching in hydrofluoric acid (HF) is one of the most common routes for the surface texturing of silica, leading to improved optical properties, which find applications in several fields. In this work, wet etching of silica is mediated by the deposition of chemically synthesized gold nanoparticles (NPs) on the substrate. NPs of different sizes are coated on silica and act as a mask when etching using HF. The effect of parameters such as etching time, NP size, and HF concentration on the surface morphologies and transmittance are studied and correlated with the chemical etching mechanism. This work reveals that a proper choice of masking and etching conditions can modulate the optical transmission of silica. Etching leads to the formation of arrays of micron-size elongated pits. The pit width and surface roughness are found to increase with etching time and HF concentration, in turn leading to a decrease in transmittance. The results show that NP masking is an effective way to control silica etching and in turn, modifies the transmittance of the substrate.

No abstract available

Atmospheric plasma etching (APE) has been used to texture Si surfaces due to anisotropic material removal capability. Controlling features and size of the light-trapping structure are keys to improving the reflection performance of silicon (Si) solar cells, which need to fully understand the interfacial etching behavior and the microscopic topography formation mechanism of the Si surface. In this study, microwave plasma with a temperature below 100 °C is employed to investigate the dependence of microstructure evolution on the O/F atom ratios in plasma. The results show that as the O/F atom ratios increase, the microstructure of the Si surface changes from square opening pits to spherical opening pits. High-resolution transmission electron microscopy and x-ray photoelectron spectroscopy analyses indicate that the exciting F atoms dominate the orientation-selective etching process, causing the formation of square opening pits. The CFx and C2 radicals induce the generation of the Si interface reactive layer, resulting in the occurrence of amorphous layers and termination of the non ⟨111⟩-crystal face in APE. The exciting O atoms preferentially occupy the active site of Si surfaces, causing the isotropic etching and then the formation of spherical opening pits. In addition, the richer O atoms will weaken the anisotropic etching ability of F atoms, resulting in the etched surface trends’ flattening. The insight into anisotropic etching behavior and topography formation mechanism of the silicon surface textured by atmospheric plasma is valuable for developing a new texturing approach to silicon solar cells.

Silicon nanopore arrays are widely used in applications such as solution exchange, biomolecule detection, chemical analysis, and plant pathogen detection due to their high stability, long service life, and excellent compatibility with semiconductor and microfluidic technologies. However, existing fabrication methods such as wet etching, ion track etching, and electron beam lithography-assisted reactive ion etching face limitations, including poor size uniformity, uneven pore distribution, and high production costs. To address these challenges, this study proposes an improved metal-assisted chemical etching method for fabricating silicon nanopore arrays. This method combines silver nanoparticle-assisted etching with an anodic aluminum oxide template, promoting the orderly arrangement of silver nanoparticles on the silicon surface. By altering key factors such as nanoparticle size, etching time, temperature, and etchant oxidant concentration, the etching process was significantly optimized, with higher temperatures and oxidant concentrations accelerating nanopore formation. In addition, it is proposed that the anodic reaction likely involves the direct dissolution of silicon in its divalent state, with the gas generated during the etching process being a product of this reaction. Xenon lamp irradiation was used to fine-tune the etching kinetics, further optimizing the morphology of the silicon nanopores. The proposed technique is low-cost, highly adaptable, and reproducible, and has been successfully applied to design and optimize silicon nanopore arrays for various advanced applications. Compared to traditional industrial methods, this fabrication approach is more suitable for large-scale production, offering higher efficiency and better geometric control, making it ideal for applications in catalysis, sensing, and nanoelectronics.

No abstract available

An efficient preparation process for Al hole array structures emitting wavelength-selective thermal radiation that is based on the anisotropic anodic etching of Al was demonstrated. The formation of an ordered hole array was achieved by a masking process prior to the anodic etching. The present process allows the preparation of large samples because the masking of the Al foil has a high throughput owing to the simple printing process using a flexible stamp. The thermal radiation properties of the Al hole array could be controlled by adjusting the depth and aperture size of the holes.

Mg is a low-cost, earth-abundant, and biocompatible plasmonic metal. Fine tuning of its optical response, required for successful light-harvesting applications, can be achieved by controlling Mg nanoparticle size and shape. Mg's hexagonal close packed crystal structure leads to the formation of a variety of unique shapes in colloidal synthesis, ranging from single crystalline hexagonal platelets to twinned rods. Yet, shape control in colloidal Mg nanoparticle synthesis is challenging due to complex nucleation and growth kinetics. Here, we present an approach to manipulate Mg nanoparticle shape by one-pot synthesis followed by colloidal etching with polycyclic aromatic hydrocarbons. We demonstrate how tips and edges in faceted Mg nanoparticles can be preferentially etched to produce quasi-spherical nanoparticles with smooth surfaces. The developed approach provides an essential shape control tool in colloidal Mg synthesis potentially applicable to other oxidising metals.

To improve the therapeutic effect of sonodynamic therapy (SDT), more effective and stable sonosensitizers and therapeutic strategies are still required. A covalent organic framework (COF) sonosensitizer is developed by using a new nanoscale COF preparation strategy. This strategy uses molecular etching based on the imine exchange reaction to etch the bulk COF into nanoparticles and has universal applicability to imine‐bond‐based COF. The regular COF structure can prevent the loss of sonodynamic performance caused by the aggregation of porphyrin molecules and improve the chemical stability of the porphyrin unit. In addition, the coordination of Fe3+ to COF endows the nanoparticle with chemodynamic therapy performance and glutathione consumption ability. The combination of enhanced SDT and α‐PD‐L1 antibody achieves a good antitumor effect. The innovative nanoscale COF sonosensitizer preparation strategy provides a new avenue for clinical antitumor therapy.

Micro-LED devices smaller than 5 µm are attracting increasing attention as next-generation display technologies for VR/AR applications due to their potential for low current density operation, high resolution, and high brightness across the primary colors. However, a major challenge remains: luminescence efficiency drops significantly at low current densities. This is primarily attributed to reduced internal quantum efficiency caused by defects introduced at the device sidewalls during fabrication. To address this issue, we investigated the application of neutral beam etching (NBE)—an ultra-low-damage etching technique—for micro-LED processing [1]. We fabricated both InGaN/GaN blue and AlGaInP red micro-LEDs, with a focus on optimizing etching conditions and elucidating the etching mechanisms specific to each material system. For blue micro-LEDs, we compared NBE processes using hydrogen iodide (HI) and chlorine (Cl₂) gases. The etching byproduct of HI and indium, InI₃, is more volatile than the corresponding chlorine-based compound, InCl₃, suggesting a potential for cleaner and less damaging surfaces. Blue micro-LEDs ranging in size from 3.5 × 3.5 µm² to 20 × 20 µm² were fabricated using commercial InGaN/GaN multiple quantum well (MQW) blue LED wafers grown on sapphire substrates. Both HI and Cl₂ were supplied at 50 sccm under a chamber pressure of 0.2 Pa and a stage temperature of 130°C. Due to the difficulty of etching the electron blocking layer (AlGaN) with HI alone, the initial 180 nm was etched using Cl₂ NBE. Subsequently, HI NBE was applied for 30 minutes at an etch rate of 14.1 nm/min, resulting in a total etching depth of 603 nm as shown in Fig. 1(a). The etched surfaces were free of residues, attributed to the high volatility of InI₃ [2]. Mesa sidewalls exhibited an angle of 103° relative to the surface, indicating favorable anisotropy. Figure 1(b) shows the external quantum efficiency (EQE) of a 3.5 × 3.5 µm² blue micro-LED as a function of current density. A peak EQE of 8.5% was achieved at a low current density of 3 A/cm², with only a 43% decrease at 0.01 A/cm². These results demonstrate that HI NBE enables the fabrication of high-efficiency sub-5-µm blue GaN micro-LEDs with performance comparable to those processed using Cl₂ NBE, while potentially reducing sidewall damage and surface roughness. In contrast, for red micro-LEDs, InGaN-based MQWs require high indium content (>35%) to achieve red emission, often resulting in severe lattice strain and reduced luminescence efficiency. Therefore, AlGaInP-based structures are more commonly employed. However, processing AlGaInP micro-LEDs is challenging—especially in structures containing both high-In-content layers and GaP layers—due to differences in etch rates that lead to excessive side etching of the GaP layer. To mitigate this, we investigated the etching behavior of GaP using Cl₂ and Cl₂/BCl₃ NBE. Test samples consisted of AlGaInP MQW structures with a 0.81 µm GaP cap layer on GaAs substrates. Etching was conducted under a chamber pressure of 0.19 Pa using gas flow rates of 50 sccm (Cl₂ NBE) and 42/8 sccm (Cl₂/BCl₃ NBE), with stage temperatures of −20°C, 40°C, and 150°C to assess temperature dependence. Figure 2 shows cross-sectional SEM analysis revealed a strong temperature dependence in side etching. Cl₂/BCl₃ NBE exhibited particularly high side etch rates at elevated temperatures, reaching 457 nm/min at 150°C. This is attributed to increased chlorine radical concentration and enhanced volatility of phosphorus chlorides at high temperatures. Conversely, side etching was significantly suppressed at temperatures below 40°C. These findings suggest that for AlGaInP red micro-LEDs, minimizing side etching of the GaP layer requires low-temperature processing, ideally below 40°C, to achieve more anisotropic profiles essential for efficient light emission and device reliability. In conclusion, our study demonstrates that neutral beam etching (NBE) is a highly promising approach for the fabrication of sub-5-µm micro-LEDs, offering low damage and precise control over etch profiles. For blue InGaN/GaN micro-LEDs, HI-based NBE provided smooth surfaces and high EQE at low current densities, attributed to the high volatility of iodine-based byproducts and reduced sidewall damage. For red AlGaInP micro-LEDs, we clarified the temperature-dependent etching behavior of GaP and demonstrated that maintaining stage temperatures below 40°C significantly reduces side etching, improving anisotropy. These insights contribute to the realization of high-performance, full-color micro-LED displays for future VR/AR applications. [1] X. L. Wang, et al., Nat Commun 14, 7569 (2023). [2] D. Ohori et al., Nanotechnology 34 (2023) 365302. Figure 1

The synthesis of nanoparticles with a hollow and anisotropic structure have attracted considerable interest in synthetic methodology and diverse potential applications, but endowing them with delicate control of the hollow structure and outer anisotropic morphology remains a significant challenge. In this study, anisotropic nanoparticles with hat-like morphology are prepared via a kinetics-controlled growth and dissolution strategy. Starting from forming solid polymer nanospheres with location-specific compositional chemistry distribution based on the distinct reactivity and growth kinetics of two reactants. After etching by acetone, the inhomogeneity nanospheres transformed to hat-like nanoparticles through the kinetics-controlled dissolution of two kinds of precursors. Due to chemical etching and repolymerization reactions occurring within a single nanospheres, an autonomous asymmetrical repolymerization and concave process are observed, which is novel at the nanoscale. Moreover, regulating the amount of ammonia significantly impacts the growth kinetics of precursors, primarily affecting the composition and subsequent dissolution process of solid polymer nanospheres, which play an important role in constructing polymer nanoparticles with varying morphologies and internal structures. The as-synthesized hat-like carbon nanoparticles with an open carbon structure, highly porous shell, and favorable N-doped functionalities demonstrate a potential candidate for lithium-sulfur batteries.

We demonstrate controlled fabrication of porous Si (PS) and vertically aligned silicon nanowires array starting from bulk silicon wafer by simple chemical etching method, and the underlying mechanism of nanostructure formation is presented. Silicon-oxidation rate and the electron-scavenging rate from metal catalysis play a vital role in determining the morphology of Si nanostructures. The size of Ag catalyst is found to influence the Si oxidation rate. Tunable morphologies from irregular porous to regular nanowire structure could be tailored by controlling the size of Ag nanoparticles and H2O2 concentration. Ag nanoparticles of size around 30 nm resulted in irregular porous structures, whereas discontinuous Ag film yielded nanowire structures. The depth of the porous Si structures and the aspect ratio of Si nanowires depend on H2O2 concentration. For a fixed etching time, the depth of the porous structures increases on increasing the H2O2 concentration. By varying the H2O2 concentration, the surface porosity and aspect ratio of the nanowires were controlled. Controlling the Ag catalyst size critically affects the morphology of the etched Si nanostructures. H2O2 concentration decides the degree of porosity of porous silicon, dimensions and surface porosity of silicon nanowires, and etch depth. The mechanisms of the size- and H2O2-concentration-dependent dissociation of Ag and the formation of porous silicon and silicon nanowire are described in detail.

The morphology and size control of anisotropic nanocrystals are critical for tuning shape-dependent physicochemical properties. Although the anisotropic dissolution process is considered to be an effective means to precisely control the size and morphology of nanocrystals, the anisotropic dissolution mechanism remains poorly understood. Here, using in situ liquid cell transmission electron microscopy, we investigate the anisotropic etching dissolution behaviors of polyvinylpyrrolidone (PVP)-stabilized Ag nanorods in NaCl solution. Results show that etching dissolution occurs only in the longitudinal direction of the nanorod at low chloride concentration (0.2 mM), whereas at high chloride concentration (1 M), the lateral and longitudinal directions of the nanorods are dissolved. First-principles calculations demonstrate that PVP is selectively adsorbed on the {100} crystal plane of silver nanorods, making the tips of nanorods the only reaction sites in the anisotropic etching process. When the chemical potential difference of the Cl− concentration is higher than the diffusion barrier (0.196 eV) of Cl− in the PVP molecule, Cl− penetrates the PVP molecular layer of {100} facets on the side of the Ag nanorods. These findings provide an in-depth insight into the anisotropic etching mechanisms and lay foundations for the controlled preparation and rational design of nanostructures.

Optical coating to maintain clear views in harsh environments is a vital technology to meet the increasing demand for vision assistance cameras or fully automated vehicles. In this study, the hierarchical nanostructured super-hydrophobic coating was fabricated without an expensive lithography process. First, the self-assembled Ag nano-mask was deposited on top of the SiO2 layer instead of a lithography-patterned nano-mask. Next, isotropic etching to carve the SiO2 layer and anisotropic etching to reshape the Ag nano-mask were alternatively applied to create a well-controlled hierarchical nanostructure of SiO2 in one process. The size and pitch of the nanostructure were optimized by the deposition condition of Ag and the etching condition of Ag to gradually re-shape the Ag mask during the etching process. These techniques have achieved a productive etching process to form a rigid hierarchical nanostructure on a lens surface without a lithography technique.

Nanoimprint lithography (NIL) master fidelity is governed by coupled variations beginning with resist spin-coating, proceeding through electron beam exposure, and culminating in anisotropic etch transfer. We present an integrated, physics-based simulation chain. First, it includes a spin-coating thickness model that combines Emslie–Meyerhofer scaling with a Bornside edge correction. The simulated wafer-scale map at 4000 rpm exhibits the canonical center-rise and edge-bead profile with a 0.190–0.206 μm thickness range, while the locally selected 600 nm × 600 nm tile shows <0.1 nm variation, confirming an effectively uniform region for downstream analysis. Second, it couples an e-beam lithography (EBL) module in which column electrostatics and trajectory-derived spot size feed a hybrid Gaussian–Lorentzian proximity kernel; under typical operating conditions (σtraj ≈ 2–5 nm), the model yields low CD bias (ΔCD = 2.38/2.73 nm), controlled LER (2.18/4.90 nm), and stable NMSE (1.02/1.05) for isolated versus dense patterns. Finally, the exposure result is passed to a level set reactive ion etching (RIE) model with angular anisotropy and aspect ratio-dependent etching (ARDE), which reproduces density-dependent CD shrinkage trends (4.42% versus 7.03%) consistent with transport-limited profiles in narrow features. Collectively, the simulation chain accounts for stage-to-stage propagation—from spin-coating thickness variation and EBL proximity to ARDE-driven etch behavior—while reporting OPC-aligned metrics such as NMSE, ΔCD, and LER. In practice, mask process correction (MPC) is necessary rather than optional: the simulator provides the predictive model, metrology supplies updates, and constrained optimization sets dose, focus, and etch set-points under CD/LER requirements.

Surface patterning using plasmonic nanoparticles has attracted increasing interest owing to their wide use in sensing, imaging and medical applications. In this report we demonstrate bottom-up engineering of size distribution of gold nanoparticles (AuNPs) by dewetting a thin Au film deposited on a single crystal diamond (SCD) substrate with self-organized surface structures induced by ion beam etching (IBE). 14 Å of gold was sputtered and dewetted on SCD substrates with and without self-organized nano-patterns. AuNPs on structured substrates are smaller and show narrower size distribution ($9.11 \pm 2.17$ nm, compared to a reference sample being $\mathbf{9.96}\pm \mathbf{2.94}\ \mathbf{nm}$. The center wavelength of the extinction is red-shifted to 584 nm compared to 574 nm for AuNPs on a smooth surface.

Cesium lead-halide (CsPbX3; X = Cl, Br, I) perovskite microstructure arrays have become the basis for laser array applications, due to their outstanding spectral coherence, low threshold, and wideband tunability. Furthermore, the common fabrication methods for these arrays have the limitation to achieve both tailored design and high resolution simultaneously. Herein, we report a high-precision, template-assisted, wet etching (TAWE) method for the preparation of perovskite microstructure arrays. This method possesses the advantages of flexible design, controllable size, and ultrahigh accuracy (the resolution can reach 1 μm or higher). A 20 × 20 inverted pyramid array with a diameter of 3 μm and a period of 4 μm was fabricated using this method. CsPbBr3 perovskite quantum dots fabricated by means of hot injection were filled into the inverted pyramid array via spin-coating and pumped using a laser with a wavelength of 400 nm. The lasing characteristics of the array were then measured and analyzed; the threshold was measured to be 37.6 μJ cm−2, and the full width at half maximum of the amplified spontaneous emission spectrum was found to be about 4.7 nm. These results demonstrate that perovskite microstructure arrays prepared via this method have potential applications in laser arrays.

There has been growing interest in the field of oxygen electroreduction, particularly with respect to potential applications in the science and technology of low-temperature fuel cells. Obviously, many efforts have been made to develop suitable alternative electrocatalysts efficient enough to replace electrocatalysts based on scarce strategic elements such as platinum-group metals. Despite intensive research in the area, there are still a number of fundamental problems to be resolved, and the practical oxygen reduction catalysts still utilize systems based on platinum. The present study refers to a novel and unique approach of fabrication and deposition of different sized and shaped gold and silver nanoparticles on carbon supports. Among important issues is an application of inorganic (rather than organic) capping ligands, namely polyoxometallates to modify and stabilize as well as to control size and shape of branched flower-like nanocrystals. During operation in alkaline medium, polyoxometallates disappear but catalytically highly active gold and silver remains and exhibit excellent stability. The resulting materials have occurred to show highly potent electrocatalytic properties toward electroreductions of oxygen in alkaline solution. Different concepts of synthesis, modification or functionalization of gold and silver-based systems will be elucidated, as well as important strategies to enhance the systems overall activity and stability will be discussed. The major advantage of the proposed chemical synthetic method is the integration of the superb properties of both Au or Ag nanoparticles and carbon supports in a single-step synthesis with a 100% usage of the silver and gold precursor according to the coupled plasma mass spectrometer (ICP-MS). What is even more important is that carbon based materials have occurred to act effectively as carriers for gold and silver nanostructures. Mutual activating interactions are feasible. It is believed that catalytic activity of nanoparticles may be attributed to factors such as structural and electronic effects and metal–support interactions. The conclusions are reached on the basis of diagnostic electrochemical (e.g. rotating ring disk voltammetry), spectroscopic (FTIR) and microscopic (SEM, TEM) experiments. A series of comparative experiments with different carbon carriers and model catalytic materials (e.g. Vulcan-supported platinum) have also been performed. With respect to oxygen reduction, our diagnostic experiments at different concentrations of H2O2, support a view that the effect of the fast following chemical (H2O2-reductive decomposition) reaction could be the dominating factor in explaining the observed positive potential shift observed during the oxygen reduction. The fact, that the optimum carbon-based catalytic system produced the oxygen reduction peak current comparable to that observed at the model platinum containing catalyst, would imply the efficient four-electron-type reduction mechanism. ACKNOWLEDGMENTS We acknowledge the National Science Center (NCN, Poland) under Miniatura Project No. 501/D112/66 GR-6478.

Despite considerable advancements in the synthesis of two-dimensional (2D) mesoporous nanomaterials, achieving precise control over their components, morphology, lateral dimension, and thickness remains a formidable challenge. Here, we report a rational interface-confined anisotropic assembly strategy that enables the synthesis of square-shaped 2D mesoporous nanosheets with finely tunable features including compositions (metal ion-doped mesoporous polydopamine or silica), lateral dimensions (100-200 nm), thicknesses (14-25 nm), and in-plane mesopore sizes (8-20 nm). In this strategy, truncated rhombic dodecahedral ZIF-8 metal-organic framework (MOF) nanoparticles serve as seeds to direct the selective assembly of mesoporous micelles onto their six {100} facets. The geometric confinement of these square facets guides the interfacial organization of micelles into 2D sheet-like structure, faithfully inheriting the square geometry. Following etching of the ZIF-8 seeds, the resulting nanosheets preserve their well-defined square-shaped 2D morphology and mesoporous architecture. This versatile approach enables the fabrication of diverse 2D mesoporous tunable structural attributes and metal-ion dopants. As a proof of concept, mPDA-Zn2+/Fe2+ nanosquares, featuring a uniform 2D architecture, near-infrared (NIR) photothermal properties, and Fenton-like catalytic activity, demonstrate synergistic therapeutic effects. Compared to conventional spherical analogs (1.08 × 10-8 M/s), these nanosquares (2.11 × 10-8 M/s) achieve nearly doubled maximum reaction rates and achieved remarkable tumor inhibition of up to 90%. Overall, this study establishes a novel approach for the precise engineering of 2D mesoporous nanosquares with controllable parameters, unlocking new opportunities for applications in biomedicine and beyond.

No abstract available

Polystyrene (PS) nanoparticle films with non-close-packed arrays were prepared by using ion beam etching technology. The effects of etching time, beam current, and voltage on the size reduction of PS particles were well investigated. A slow etching rate, about 9.2 nm/min, is obtained for the nanospheres with the diameter of 100 nm. The rate does not maintain constant with increasing the etching time. This may result from the thermal energy accumulated gradually in a long-time bombardment of ion beam. The etching rate increases nonlinearly with the increase of beam current, while it increases firstly then reach its saturation with the increase of beam voltage. The diameter of PS nanoparticles can be controlled in the range from 34 to 88 nm. Based on the non-close-packed arrays of PS nanoparticles, the ordered silicon (Si) nanopillars with their average diameter of 54 nm are fabricated by employing metal-assisted chemical etching technique. Our results pave an effective way to fabricate the ordered nanostructures with the size less than 100 nm.

Gradient-structured materials hold great promise in the areas of batteries and electrocatalysis. Here, yolk-shell gradient-structured SiOx -based anode (YSG-SiOx /C@C) derived from periodic mesoporous organosilica spheres (PMOs) through a selective etching method is reported. Capitalizing on the poor hydrothermal stability of inorganic silica in organic-inorganic hybrid silica spheres, the inorganic silica component in the hybrid spheres is selectively etched to obtain yolk-shell-structured PMOs. Subsequently, the yolk-shell PMOs are coated with carbon to fabricate YSG-SiOx /C@C. YSG-SiOx /C@C is comprised of a core with uniform distribution of SiOx and carbon at the atomic scale, a middle void layer, and outer layers of SiOx and amorphous carbon. This unique gradient structure and composition from inside to outside not only enhances the electrical conductivity of the SiOx anode and reduces the side reactions, but also reserves void space for the expansion of SiOx , thereby effectively mitigating the stress caused by volumetric effect. As a result, YSG-SiOx /C@C exhibits exceptional cycling stability and rate capability. Specifically, YSG-SiOx /C@C maintains a specific capacity of 627 mAh g-1 after 400 cycles at 0.5 A g-1 , and remains stable even after 550 cycles at current density of 2 A g-1 , achieving a specific capacity of 519 mAh g-1 .

Atomic layer deposition (ALD) and atomic layer etching (ALE) techniques were used to control the ZrO2 shell thickness on TiO2/ZrO2 core/shell nanoparticles. ALD and ALE were performed at 200 °C while the nanoparticles were agitated using a rotary reactor. To increase the ZrO2 shell thickness, ZrO2 ALD films were deposited using sequential exposures of tetrakis(dimethylamino) zirconium and H2O. Ex situ analysis using transmission electron microscopy (TEM) observed the growth of the ZrO2 shells. The ZrO2 ALD led to more spherical ZrO2 shells on the crystalline and irregular TiO2 cores. The ZrO2 ALD on the nanoparticles had a growth rate of 0.9 ± 0.1 Å/cycle. Tunable ZrO2 coatings were observed with thicknesses ranging from 5.9 to 27.1 nm after 240 ZrO2 ALD cycles. To demonstrate the decrease in the ZrO2 shell thickness, the ZrO2 film was then etched using sequential hydrogen fluoride (HF) and TiCl4 exposures. Quadrupole mass spectrometry experiments performed in a separate reactor identified the volatile products during ZrO2 ALE. H2O was monitored during HF exposures, and ZrCl4 etch products and TiFxCly ligand-exchange products were observed during TiCl4 exposures. Ex situ TEM studies revealed that the ZrO2 shells remained spherical during ZrO2 ALE. The ZrO2 ALE on the nanoparticles had an etch rate of 6.5 ± 0.2 Å/cycle. Tunable ZrO2 coatings were produced from 27.1 down to 7.6 nm using 30 ZrO2 ALE cycles. This study demonstrated that ZrO2 ALD and ZrO2 ALE can control the thickness of ZrO2 shells on TiO2/ZrO2 core/shell nanoparticles without inducing nanoparticle agglomeration.

Great interest is shown toward atomic layer etching (ALE) processes due to the better control of the etching process and higher selectivity that they can offer. In order to obtain these benefits, the ALE steps must be self-limited. In the case of SiO2 ALE, the passivation step often relies on the deposition of a fluorocarbon film on the surface of SiO2. This reaction is not self-limited, which can lead to a drift of the amount of material etched per cycle with the increasing number of cycles. The drift of these processes can be detected through thickness measurements, but this is often not available in situ in manufacturing tools. For this reason, this study focuses on finding a way to detect the drift of these processes using optical emission spectroscopy (OES) that is more likely available in situ in manufacturing tools. Results presented in this paper first characterize the drift of quasi-ALE of thermal SiO2 using spectroscopic ellipsometry and x-ray photoelectron spectroscopy. OES spectra are then studied to identify a marker of the drift of the process in agreement with previous measurements. The drift of the process is found to be dependent on the durations of the deposition and activation steps. The intensity of the line of emission at a wavelength of 251 nm, attributed to CF or CF2, is found to be a marker of the drift of the process.

Applications of zinc-air batteries are partially limited by the slow kinetics of oxygen reduction reaction (ORR); Thus, developing effective strategies to address the compatibility issue between performance and stability is crucial, yet it remains a significant challenge. Here, we propose an in situ gas etching-thermal assembly strategy with an in situ-grown graphene-like shell that will favor Mn anchoring. Gas etching allows for the simultaneous creation of mesopore-dominated carbon cores and ultrathin carbon layer shells adorned entirely with highly dispersed Mn-N4 single-atom sites. This approach effectively resolves the compatibility issue between activity and stability in a single step. The unique core-shell structure allows for the full exposure of active sites and effectively prevents the agglomerations and dissolution of Mn-N4 sites in cores. The corresponding half-wave potential for ORR is up to 0.875 V (vs. reversible hydrogen electrode (RHE)) in 0.1 M KOH. The gained catalyst (Mn-N@Gra-L)-assembled zinc-air battery has a high peak power density (242 mW cm-2) and a durability of ∼ 115 h. Furthermore, replacing the zinc anode achieved a stable cyclic discharge platform of ∼ 20 h at varying current densities. Forming more fully exposed and stable existing Mn-N4 sites is a governing factor for improving the electrocatalytic ORR activity, significantly cycling durability, and reversibility of zinc-air batteries.

This study aimed to evaluate the SiO2 atomic layer etching (ALE) process that is selective to Si3N4 based on the physisorption of high boiling point perfluorocarbons (HBP PFCs; C5F8, C7F14, C6F6, and C7F8 have boiling points above room temperature). The lowering of the substrate temperature from 20 °C to -20 °C not only increased SiO2 etch depth per cycle (EPC) but also increased etch selectivity of SiO2/Si3N4 to near infinity. Due to the differences in fluorocarbon adsorption at a temperature during the physisorption depending on boiling points of PFCs, the desorption time and ion bombardment energy during the desorption step needed to be optimized, and higher ion bombardment energy and longer desorption time were required for higher HBP PFCs. Even though near infinity etch selectivity of SiO2/Si3N4 was obtained, for the SiO2 etching masked with Si3N4 patterns, due to the adsorption of PFC on the sidewall of the Si3N4 layer, the difficulty in anisotropic etching could be observed. By adding an O2 descumming step in ALE processes, an anisotropic SiO2 etch profile could be obtained with no adsorption of fluorocarbon on the chamber wall. Therefore, it is believed that the HBP ALE processes can be applicable for achieving high selective SiO2/Si3N4 with more stability and reliability.

This research investigates the improvements of ozone (O3) annealing on the optical and etching characteristics of TiO2/Al2O3 multilayer band-pass filters designed for potential optoelectronic applications. The band-pass filters were fabricated using atomic layer deposition (ALD), and their performance was systematically analyzed after the addition of O3 annealing at moderate temperatures (up to 300 °C). Results reveal that O3 annealing improves the optical transmittance of the multilayers by approximately 40% without significant spectral changes (∼6 nm). The observed enhancement in the transmittance is attributed to the improved stoichiometry of TiO2. By filling in the oxygen vacancies created during the fabrication process, it reduces its extinction coefficient. Furthermore, the O3 annealing enhances the stability of TiO2 against wet etching, improving the uniformity of etched surfaces. Etching on the ozone-annealed multilayer was up to 8 times more homogeneous, as observed in the roughness. The relatively short duration of the O3 annealing process, approximately 1.6 h, makes it a cost-effective alternative compared to using ozone in the ALD process, which can last several hours for thick optical coatings.

It is of great significance to explore high activity, low overpotential, and outstanding durability electrocatalysts without precious metals for oxygen evolution reaction to reduce the energy consumption in the electrolysis of water to product hydrogen. Metal organic frameworks (MOFs) with periodic structure and uniform pore distribution have been widely used as precursors for the synthesis of transition metal electrocatalysts. Herein, we first synthesized nanoscale Fe-soc-MOFs with relatively high specific surface area and in situ converted it into nickel-iron double layer hydroxide/MOF (FeNi LDH/MOF) by Ni2+ etching. Finally, a nickel-iron phosphide/nitrogen-doped carbon cubic nanocage (FeNiP/NC) was obtained by calcination and phosphating. FeNiP/NC with its unique core-shell structure has an overpotential of only 240 mV at a current density of 10 mA/cm2 and can be continuously electrolyzed for 45 h. High catalytic activity of FeNiP/NC is mainly attributed to the action of Fe and Ni bimetals and the synergistic effect between FeNiP and N-doped porous carbon, which was confirmed by the calculation of density functional theory (i.e., Gibbs free energy). After a long period of electrolysis, FeNiP was converted to MOOH (M = Fe and Ni) and became the new active site. This study provides a feasible optimization strategy for the development of high-efficiency three-dimensional electrode materials without precious metals.

Wearable sweat sensors have garnered substantial attention owing to their actual significance in the noninvasive and real-time monitoring of health conditions. However, it remains significantly challenging to efficiently construct a high-sensitivity sweat sensor with stable long-term sensing capability. Herein, we report an effective methodology based on wet-spinning/acid-etching technology to construct a porous core-shell yarn-based wearable electrochemical sensor. This strategy increases the inductive surface area of the ion concentration and facilitates signal transmission. As a result, the sensor demonstrates high sensitivity for monitoring K+ and pH in sweat (54.89 mV/dec for K+ and 40.2 mV/pH for pH). Furthermore, the sensors exhibit outstanding sensing stability, good long-term stability (>16 h), and satisfactory bending resistance (>1000 cycles). More importantly, the sensing yarns could be prepared at speeds of up to 500 m/h with a continuous preparation strategy, which enabled mass fabrication of the electrochemical sensor. Electrochemical sensors could serve as sweat-sensing systems for real-time health monitoring and hold great potential for the commercialization of health-detection technology.

No abstract available

Diamond is a promising material for multiple applications in quantum information processing and sensing as well as applications in microelectronics. However, diamond devices can be limited by surface defects that compromise charge stability and spin coherence, among others. Improved strategies in plasma etching of diamond could play an important role in minimizing or eliminating these defects. In this work, we explore plasma-assisted atomic scale etching of diamond using argon ions (Ar+), hydrogen ions (H+) and hydrogen atoms (H). We employ classical molecular dynamics (MD) simulations and test several interatomic potentials based on the Reactive Empirical Bond Order (REBO) form with comparisons to a variety of published experimental results. We performed MD simulations of low-energy hydrogen ( ⩽50 eV) and argon ( ⩽200 eV) ion bombardment of diamond surfaces. Ar+ bombardment can be used to locally smooth initially rough diamond surfaces via the formation of an amorphous C layer, the thickness of which increases with argon ion energy. Subsequent exposure with hydrogen ions (or fast neutrals) will selectively etch this amorphous C layer, leaving the underlying diamond layer mostly intact if the H energy is maintained below about 10 eV. The simulations suggest that combining Ar+ smoothing with selective, near threshold energy H removal of amorphous C can be an effective strategy for diamond surface engineering, leading to more reliable and sensitive diamond color center devices.

Sodium-ion batteries (SIBs) are becoming an alternative option for large-scale energy storage systems owing to their low cost and abundance. The lattice oxygen redox (LOR), which has the potential to increase the reversible capacity of materials, has promoted the development of high-energy cathode materials in SIBs. However, the utilization of oxygen anion redox reactions usually results in harmful lattice oxygen release, which hastens structural deformation and declines electrochemical performance, severely hindering their practical application. Herein, a ribbon-ordered superstructured P3-type Na0.6Li0.2Mn0.8O2 (NLMO) cathode with a uniform Al2O3 coating through atomic layer deposition (ALD) was synthesized. The cycling stability and rate capability of the materials were improved by a proper thickness of the Al2O3 layer. Differential electrochemical mass spectrometry (DEMS) results clearly suggest that the Al2O3 coating can inhibit the CO2 release caused by the highly active surface of the NLMO material. Moreover, the results of transmission electron microscopy (TEM) and etching X-ray photoelectron spectroscopy (XPS) show that the Al2O3 coating can effectively prevent electrolyte and electrode side reactions and the dissolution of Mn. This surface engineering strategy sheds light on the way to prolong the cycling stability of anionic redox cathode materials.

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The exposure of workers to propylene glycol monomethyl ether acetate (PGMEA) in manufacturing environments can result in potential health risks. Therefore, systems for PGMEA removal are required for indoor air quality control. In this study, core–shell zeolite socony mobil-5 (ZSM-5)/polyvinylpyrrolidone–polyvinylidene fluoride nanofibers were directly electrospun and partially wet-etched on a mesh substrate to develop a cover-free compact PGMEA air filter. The electrospinning behaviors of the core–shell nanofibers were investigated to optimize the electrospinning time and humidity and to enable the manufacture of thin and light air-filter layers. The partial wet etching of the nanofibers was undertaken using different etching solvents and times to ensure the exposure of the active sites of ZSM-5. The performances of the ZSM-5/PVDF nanofiber air filters were assessed by measuring five consecutive PGMEA adsorption–desorption cycles at different desorption temperatures. The synthesized material remained stable upon repeated adsorption–desorption cycles and could be regenerated at a low desorption temperature (80 °C), demonstrating a consistent adsorption performance upon prolonged adsorption–desorption cycling and low energy consumption during regeneration. The results of this study provide new insights into the design of industrial air filters using functional ceramic/polymer nanofibers and the application of these filters.

One-dimensional germanium (Ge)-related nanostructures including core–shell nanowires and nanotubes with high specific surface area show enhanced performance in energy storage and electronic devices, and their structural control is important for further improving their performance and stability. In this work, we fabricated vertically formed ZnO/Ge core–shell nanowires with different shell thicknesses. The dependence of morphology, crystallinity, and internal stress of the nanowires on the shell growth time and temperature was investigated. By applying the wet-etching method to the ZnO/Ge core–shell heterojunction nanowires, we demonstrated the Ge nanotube fabrication and stress relaxation in Ge after ZnO core removal.

Controlling the morphology of Pt-based nanostructures can provide a great opportunity to boost their catalytic activity and durability. Here the authors report anisotropic mesoporous Pt@Pt-skin Pt_3Ni core-shell framework nanowires for oxygen reduction reaction with enhanced mass activity and stability. The design of Pt-based nanoarchitectures with controllable compositions and morphologies is necessary to enhance their electrocatalytic activity. Herein, we report a rational design and synthesis of anisotropic mesoporous Pt@Pt-skin Pt_3Ni core-shell framework nanowires for high-efficient electrocatalysis. The catalyst has a uniform core-shell structure with an ultrathin atomic-jagged Pt nanowire core and a mesoporous Pt-skin Pt_3Ni framework shell, possessing high electrocatalytic activity, stability and Pt utilisation efficiency. For the oxygen reduction reaction, the anisotropic mesoporous Pt@Pt-skin Pt_3Ni core-shell framework nanowires demonstrated exceptional mass and specific activities of 6.69 A/mg_pt and 8.42 mA/cm^2 (at 0.9 V versus reversible hydrogen electrode), and the catalyst exhibited high stability with negligible activity decay after 50,000 cycles. The mesoporous Pt@Pt-skin Pt_3Ni core-shell framework nanowire configuration combines the advantages of three-dimensional open mesopore molecular accessibility and compressive Pt-skin surface strains, which results in more catalytically active sites and weakened chemisorption of oxygenated species, thus boosting its catalytic activity and stability towards electrocatalysis.

We report an atomic scale controllable synthesis of Pd/Pt core shell nanoparticles (NPs) via area-selective atomic layer deposition (ALD) on a modified surface. The method involves utilizing octadecyltrichlorosilane (ODTS) self-assembled monolayers (SAMs) to modify the surface. Take the usage of pinholes on SAMs as active sites for the initial core nucleation and subsequent selective deposition of the second metal as the shell layer. Since new nucleation sites can be effectively blocked by surface ODTS SAMs in the second deposition stage, we demonstrate the successful growth of Pd/Pt and Pt/Pd NPs with uniform core shell structures and narrow size distribution. The size, shell thickness and composition of the NPs can be controlled precisely by varying the ALD cycles. Such core shell structures can be realized by using regular ALD recipes without special adjustment. This SAMs assisted area-selective ALD method of core shell structure fabrication greatly expands the applicability of ALD in fabricating novel structures and can be readily applied to the growth of NPs with other compositions.

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Rationally designing the core/shell architecture of Pt-based electrocatalysts has been demonstrated as an effective way to induce surface strain effect for promoting the sluggish kinetics of oxygen reduction reaction (ORR) at the cathode of fuel cells. However, the unstable core dissolution and structural collapse usually occur in Pt-based core/shell catalysts during the long-term cycling operation, greatly impacting the actual fuel cells applications. Impeding the dissolution of cores beneath the Pt shells is the key to enhancing the catalytic stability of materials. Herein, a method for sandwiching atomic PdAu interlayers into one-dimensional (1D) Pd/Pt core/shell nanowires (NWs) is developed to greatly boost the catalytic stability of subnanometer Pt shells for ORR. The Pd/PdAu/Pt core/shell/shell NWs display only 7.80% degradation of ORR mass activity over 80 000 potential cycles with no dissolution of Pd cores and well preservation of the holistic sandwich core/shell nanostructures. This is a significant improvement of electrocatalytic stability compared with the Pd/Pt core/shell NWs that deformed and inactivated over 80 000 potential cycles. The density functional theory (DFT) calculations further demonstrate that the electron-transfer bridge Pd and electron reservoir Au, served in the PdAu atomic interlayer, both guarantee the preservation of the high electroactivity of surface Pt sites during the long-term ORR stability test. In addition, the Pd/PdAu/Pt NWs show 1.7-fold higher mass activity (MA) for ORR than the conventional Pd/Pt NWs. The enhanced activity can be attributed to the strong interaction between PdAu interlayers and subnanometer-Pt shells, which suppresses the competitive Pd-4d bands and boosts the surface Pt-5d bands towards Fermi level for higher electroactivity, proved from DFT.

Developing pure inorganic materials capable of efficiently co-removing radioactive I2 and CH3 I has always been a major challenge. Bismuth-based materials (BBMs) have garnered considerable attention due to their impressive I2 sorption capacity at high-temperature and cost-effectiveness. However, solely relying on bismuth components falls short in effectively removing CH3 I and has not been systematically studied. Herein, a series of hollow mesoporous core-shell bifunctional materials with adjustable shell thickness and Si/Al ratio by using silica-coated Bi2 O3 as a hard template and through simple alkaline-etching and CTAB-assisted surface coassembly methods (Bi@Al/SiO2 ) is successfully synthesized. By meticulously controlling the thickness of the shell layer and precisely tuning of the Si/Al ratio composition, the synthesis of BBMs capable of co-removing radioactive I2 and CH3 I for the first time, demonstrating remarkable sorption capacities of 533.1 and 421.5 mg g-1 , respectively is achieved. Both experimental and theoretical calculations indicate that the incorporation of acid sites within the shell layer is a key factor in achieving effective CH3 I sorption. This innovative structural design of sorbent enables exceptional co-removal capabilities for both I2 and CH3 I. Furthermore, the core-shell structure enhances the retention of captured iodine within the sorbents, which may further prevent potential leakage.

In the present study, Ti3C2Tx type MXene was prepared by selective etching of Al from Ti3AlC2 with mesh size of 200. The powder form of raw material was used to fabricate Ti3C2Tx by in-situ HF etching method. The MXene is further coated on non-woven paper by simply dip coating method. The detailed structural, morphology and elemental content study of as prepared Ti3C2Tx MXene have demonstrated. The MXene (Ti3AlC2) powders show compact, layered morphology as expected for bulk layered ternary carbide. The detailed elemental analysis has carried out for Titanium carbide based MXene coated and uncoated woven paper. The lower conducting property obtained for paper coating due less amount of coating in the surface of paper instead of coating on glass substrate. The electrical property characterization of MXene coated non-woven paper and glass substrate have also been studied. Hence, the conductive coating of MXene-in water formulation achieved through simple dip coating methods is promising for low cost sensor, wearable shielding device fabrication towards renewable energy and healthcare applications.

In this study, low-temperature synthesis of a Nb2SnC non-MAX phase was carried out via solid-state reaction, and a novel approach was introduced to synthesize 2D Nb2CTx MXenes through selective etching of Sn from Nb2SnC using mild phosphoric acid. Our work provides valuable insights into the field of 2D MXenes and their potential for energy storage applications. Various techniques, including XRD, SEM, TEM, EDS, and XPS, were used to characterize the samples and determine their crystal structures and chemical compositions. SEM images revealed a two-dimensional layered structure of Nb2CTx, which is consistent with the expected morphology of MXenes. The synthesized Nb2CTx showed a high specific capacitance of 502.97 Fg−1 at 1 Ag−1, demonstrating its potential for high-performance energy storage applications. The approach used in this study is low-cost and could lead to the development of new energy storage materials. Our study contributes to the field by introducing a unique method to synthesize 2D Nb2CTx MXenes and highlights its potential for practical applications.

With increasing industrialization in the modern era, the detection of hazardous gases like NH3 became a global issue due to its detrimental effect on mankind. MXene has emerged as an outstanding gas sensing candidate among two-dimensional materials due to its favorable characteristics like an abundance of interaction sites, metallic conductivity, tunable surface properties, band gap, and excellent mechanical strength. In the present work, a highly sensitive and selective NH3 gas sensor has been fabricated using MXene-based nanostructures. The morphological and structural characterizations of nanostructures have been performed using X-ray diffraction, field-emission scanning electron microscopy, and transmission electron microscopy. The successful etching of Al reveals the formation of MXene having exfoliated multilayered morphology with an average interlayer spacing of ~53 nm. The response kinetics of the sensor has been investigated by estimating their response and selectivity toward different oxidizing and reducing gases. The sensor exhibits high response transient curves toward 5–100 ppm of NH3 at room temperature (30 °C) with fast response and recovery time. Density functional theory has been used to elucidate the interaction mechanism between NH3 molecules and MXene surface.

The growing threat of antimicrobial resistance and tuberculosis (TB) necessitates innovative therapeutics capable of modulating both infection and host immune responses. In this study, we report the dual anti-tubercular and anti-inflammatory activity of oxygen-functionalized Ti3C2O2 MXene, a two-dimensional nanomaterial synthesized via selective HF etching of Ti3AlC2 followed by ethanol-assisted delamination. Structural characterization by XRD and Raman spectroscopy confirmed successful conversion to the MXene phase, with an increased interlayer spacing of 9.87 Å. SEM and TEM analyses revealed uniform sheet-like morphology, and AFM confirmed few-layer thickness (∼1.5 nm). Biological assays using lipopolysaccharide (LPS)-stimulated murine macrophage cell line RAW 264.7 macrophages demonstrated significant downregulation of pro-inflammatory mediators- inducible nitric oxide synthase (iNOS), Tumor necrosis factor (TNF)-α, and Interleukin-6 (IL-6)-with IC50 values of 23.2, 26.1, and 21.6 μg mL-1, respectively. Western blot analysis further validated suppression of inflammatory pathways at the protein level. In parallel, Ti3C2O2 exhibited robust anti-tubercular activity against Mycobacterium tuberculosis H37Rv, achieving complete inhibition at 4.0 μg mL-1. Computational studies revealed strong and specific interaction of Ti3C2O2 with the TB inflammatory target protein (PDB ID: 5V3Y), forming stable hydrogen bonds with His185, Gln186, and Asp219. Molecular dynamics simulations over 3000 ns confirmed a highly stable protein-MXene complex (RMSD: 2.41 Å; ΔGbind: -78.54 kcal mol-1). Comparative simulations with streptomycin revealed weaker binding and greater structural fluctuation. ADMET predictions suggested favorable pharmacokinetic properties, including high volume of distribution, low toxicity, and absence of major cytochrome P450 or cardiotoxic liabilities. These findings establish Ti3C2O2 MXene as a promising nanoplatform for dual-function immunomodulation and antimicrobial therapy, offering mechanistic and structural insight into its bioactivity.

Titanium carbide (Ti3C2) MXene, a 2D material derived from the MAX phase, was synthesized from Ti3AlC2 via selective etching of an aluminum layer using lithium fluoride (LiF) and hydrochloric acid (HCl). Fourier‐transform infrared spectroscopy (FTIR) revealed the introduction of new surface functional groups (–F, –OH, –O), Raman spectroscopy confirmed the removal of the Al layer, and X‐ray diffraction (XRD) showed a significant increase in interlayer spacing (17.48 Å versus 3.54 Å for MAX), accompanied by a reduction in crystallite size and an increase in microstrain. Scanning electron microscopy (SEM) revealed a clear transformation from a compact layered structure to a porous, exfoliated morphology, while thermogravimetric analysis (TGA) demonstrated stability up to 800 °C, with multi‐stage mass loss due to the decomposition of surface terminations. The synthesized Ti3C2 MXene was incorporated into a polyvinyl alcohol (PVA) matrix to fabricate PVA/Ti3C2 composite films for food packaging applications. These composites exhibited markedly reduced water absorption, improved oxygen barrier performance, and enhanced thermal resistance compared with pure PVA, confirming the beneficial role of MXene as a functional nanofiller. Such improvements are particularly important for sustainable food packaging, in which maintaining product quality, extending shelf life, and reducing food waste are critical objectives. The use of biodegradable PVA further supports environmental goals by providing a viable alternative to petroleum‐based plastics, whereas the tunable nature of MXene–polymer interactions opens avenues for advanced packaging designs with multifunctional capabilities.

This study investigates the structural and phase stability of $\text{Ti}_{3} \mathrm{C}_{2}$ MXene synthesized via selective etching of $\text{Ti}_{3} \text{AlC}_{2}$ MAX-phase powder in mixed HCl and HF acids. Flexible nanostructured films were prepared by vacuum filtration of $\text{Ti}_{3} \mathrm{C}_{2}$ colloidal solution In-situ X-ray diffraction analysis revealed that initial heating triggers deintercalation and decomposition of intercalated water and hydroxyl groups, with accelerated kinetics in air due to ambient oxygen. Above 600° C, pronounced oxidation forms $\text{TiO}_{2}$, persisting under vacuum via residual surface-bound oxygen and trace atmospheric oxygen. Post $-800^{\circ} \mathrm{C}$ exposure, both air and vacuum-treated samples exhibited loss in plasticity and altered surface morphology by formation of $\text{TiO}_{2}$ crystals, with no detectable phase transformation of $\text{Ti}_{3} \mathrm{C}_{2}$ to cubic TiC. Heat treatment in vacuum and in air leading to reduction of interplanar distance of $\text{Ti}_{3} \mathrm{C}_{2}$ MXene related to changes in functional surface groups of MXene. These results underscore environmental oxygen's critical role in MXene's thermal degradation pathways, necessitating stringent atmospheric control for high-temperature applications to mitigate oxidation-driven structural changes.

MXenes, a prominent class of 2-dimensional transition metal carbides, are generally obtained via selective removal of the ‘A’ element from MAX phases using fluoride-based etchantsConventional delamination often leaves a considerable fraction of flakes trapped in sediment, lowering yield and limiting scalability. Here, we demonstrate a modified recovery approach for sediment-trapped Ti3C2Tₓ MXene, enabling direct film formation without additional chemical agents. Ti3AlC2 MAX phase was first synthesized via pressureless sintering at 1450 °C for 3 h under argon. Selective etching was performed using an HF/HCl mixture, followed by LiCl-assisted washing. The resulting MXene was obtained in two forms: (1) a colloidal suspension (average flake size ∼700 nm) for solution-based applications, and (2) a thin layer of hexagonal flakes (∼10 μm) deposited on glass via a single dip-coating transfer. XRD confirmed structural integrity, SEM revealed well-preserved hexagonal morphology, and FTIR/Raman identified hydrophilic −O and −OH surface terminations. This recovery method not only improves overall MXene yield but also offers a straightforward route for preparing uniform Ti3C2Tₓ films, with potential for scalable integration in electronics, energy storage, and sensor technologies.

The integration of MXenes, a class of conductive two-dimensional materials, into the microelectronics industry is largely hindered by the lack of scalable patterning methods. Herein, we present a novel wet etching approach for Ti3C2T z MXene micropatterning, offering a facile, clean, cost-effective, and highly controllable technique that preserves the MXene intrinsic electrical and structural properties. By tailoring the etching solution and process parameters, micropatterned MXene electrodes with ∼200 nm lateral resolution were produced. The patterned films were applied to functional devices, including metal–semiconductor−metal (MSM) photodetectors, which demonstrated high conductivity and enhanced photoresponsivity. This work represents the first demonstration of wet etching as a viable method for highly precise MXene patterning, providing a scalable solution for next-generation MXene-based microelectronic technologies.

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Anisotropic etching is a novel and effective means to modulate facets of metal-organic frameworks (MOFs) which deserves continuous exploration. Herein, we developed a facet-selective protection and etching method to achieve morphology control of MOFs. Our approach exploits the compositional differences between the facets of zeolitic imidazolate framework-67 and the moderate coordinating and etching properties of ethylenediaminetetraacetic acid disodium salt (EdtaH2Na2). The selected chelator, EdtaH22-, can specifically coordinate with unsaturated metal sites on the {100} crystal planes, protecting them from proton etching and meanwhile releasing protons. Moreover, the released protons with locally high concentration led to the etching of the unprotected {110} facets, ultimately forming nanocrystals with selectively exposed surfaces. This anisotropic etching strategy facilitates the precise modification of MOF surfaces, which is anticipated to play a crucial role in enhancing their properties in different application areas.

Aqueous zinc-ion batteries (AZIB) are significantly constrained by the poor stability of Zn anodes in aqueous electrolytes, which is caused by uncontrollable deposition behavior and parasitic reactions. The construction of specific crystalline surfaces represents an effective method for stabilizing Zn anodes. Therefore, a stable Malic acid@Zn (MA@Zn) anode with a highly (101) texture configuration is developed through acid etching. The mechanism of MA selective etching is investigated through theoretical calculations, where Zn atoms detach from the (002) crystal surface due to the strong interaction of MA with the (002) surface, leading to the preferential corrosion of the (002) surface and the formation of a unique (101) texture configuration morphology. This texture is conducive to the MA@Zn anode, as it enhances the affinity of MA@Zn for Zn2+ and optimizes the electric field distribution on the surface, thereby facilitating a more stable Zn deposition. Consequently, the MA@Zn symmetric battery is subjected to stable cycling for a period exceeding 2400 h at a current density of 5 mA cm-2. In comparison, the cycle life of the Zn//V2O5 full battery is significantly improved by >6000 cycles, pouch battery also shows better performance.

Single atom catalysts possess attractive electrocatalytic activities for various chemical reactions owing to their favorable geometric and electronic structures compared to the bulk counterparts. Herein, we demonstrate an efficient approach to producing single atom copper immobilized MXene for electrocatalytic CO2 reduction to methanol via selective etching of hybrid A layers (Al and Cu) in quaternary MAX phases (Ti3(Al1-xCux)C2) due to the different saturated vapor pressures of Al- and Cu-containing products. After selective etching of Al in the hybrid A layers, Cu atoms are well-preserved and simultaneously immobilized onto the resultant MXene with dominant surface functional group (Clx) on the outmost Ti layers (denoted as Ti3C2Clx) via Cu-O bonds. Consequently, the as-prepared single atom Cu catalyst exhibits a high Faradaic efficiency value of 59.1% to produce CH3OH and shows good electrocatalytic stability. On the basis of synchrotron-based X-ray absorption spectroscopy analysis and density functional theory calculations, the single atom Cu with unsaturated electronic structure (Cuδ+, 0 < δ < 2) delivers a low energy barrier for the rate-determining step (conversion of HCOOH* to absorbed CHO* intermediate), which is responsible for the efficient electrocatalytic CO2 reduction to CH3OH.

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The stringent safety protocols required for hydrofluoric acid (HF) based MAX phase etching and the reliance on material characterization tools such as XRD, SEM, EDS and XPS to study etching make the MXene research challenging. Here, we have employed 27Al NMR spectroscopy for the rapid detection of selective etching, directly from the etching supernatant, of soluble aluminum species generated during the MAX phase etching reaction. This technique was applied to the development of a new etching protocol for Ti3AlC2 MAX phase using the less hazardous hexafluorosilicic acid. The etching process was studied using a combination of 27Al and 19F NMR spectroscopies where it was demonstrated to be free of HF or free fluoride in quantities detectable by 19F NMR, and that the primary etching byproduct is H3AlF6. 19F NMR spectroscopy was additionally proven to be a viable technique to quantify the extent of etching using trifluoroacetic acid as an internal standard.

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Silicon nitride (Si<inf>3</inf>N<inf>4</inf>) and silicon oxide (SiO<inf>2</inf>) mulit-stack structures were widely applicated in semiconductor devices to breaking through the bottleneck problem of scaling technological nodes. Vertical trenches in Si<inf>3</inf>N<inf>4</inf>/SiO<inf>2</inf> multi-stack structures were designed in 3D memory devices to meet the requirement of scaling. Normally, phosphoric acid (H<inf>3</inf>PO<inf>4</inf>)-based etchants were used to selectively etch Si<inf>3</inf>N<inf>4</inf> sacrificial layers. During selective wet etching process, byproduct H<inf>2</inf>SiO<inf>3</inf> was generated to prevent the loss in the thickness of SiO<inf>2</inf> layers. Nevertheless, abnormal SiO<inf>2</inf> redeposition phenomenon was found when the H<inf>2</inf>SiO<inf>3</inf> concentration is supersaturated, which block Si<inf>3</inf>N<inf>4</inf> layer etching and significantly deteriorates the remaining structure morphology. In this study, the composition and formation of SiO<inf>2</inf> redeposition mechanism was investigated and discussed. Five tiers Si<inf>3</inf>N<inf>4</inf>/SiO<inf>2</inf> stack structures was designed to clarified the SiO<inf>2</inf> redeposition mechanism and the chemical composition of redeposition SiO<inf>2</inf> layer. The redeposited layer with average thickness of ~0.2x nm act as colloidal silica gel was formed when the H<inf>2</inf>SiO<inf>3</inf> concentration is supersaturated. In a phosphoric acid environment, the O-Si-O bond was broken by hydrogen bond, thus the redeposition SiO<inf>2</inf> act as colloidal silica gel and adhere onto the original ALD SiO<inf>2</inf> layers. The oxide redeposition phenomenon was related to the mass transfer rate of byproduct, the generation rate of the byproduct and the Si3N4 lateral etch rate. Our researches were very critical for the development of high density and scaling 3D memory devices.

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Solid oxide cells (SOCs) are promising energy‐conversion devices due to their high efficiency under flexible operational modes. Yet, the sluggish kinetics of fuel electrodes remain a major obstacle to their practical applications. Since the electrochemically active region only extends a few micrometers, manipulating surface architecture is vital to endow highly efficient and stable fuel electrodes for SOCs. Herein, a simple selective etching method of nanosurface reconstruction is reported to achieve catalytically optimized hierarchical morphology for boosting the SOCs under different operational modes simultaneously. The selective etching can create many corrosion pits and exposure of more B‐site active atoms in Sr2Co0.4Fe1.2Mo0.4O6‐δ fuel electrode, as well as promote the exsolution of CoFe alloy nanoparticles. An outstanding electrochemical performance of the fabricated cell with the power density increased by 1.47 times to 1.31 W cm−2 at fuel cell mode is demonstrated, while the current density reaches 1.85 A cm−2 under 1.6 V at CO2 electrolysis mode (800 °C). This novel selective etching method in perovskite oxides provides an appealing strategy to fabricate hierarchical electrocatalysts for highly efficient and stable SOCs with broad implications for clean energy systems and CO2 utilization.

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The etching process was used to create MXenes (Nb2C, Ti2C, Ti3C2, Cr2C, and V2C) utilizing their respective predecessors, MAX phases Nb2AlC, Ti2AlC, Ti3AlC2, Cr2AlC, and V2AlC. The surface morphology and structural characteristics of the material were examined using x-ray diffraction and a scanning electron microscope (SEM), respectively. The SEM pictures are used to corroborate the layer architectures of the MXenes. The estimated bandgaps range from 1.76 to 1.81 eV, aligning with published values and suitable for light interaction and photodegradation processes. The Fourier transform infrared analysis further validates the functional group of the synthesized MXenes. Higher degradation efficiencies of 96%, 94%, and 75% within 120, 160, and 160 min are demonstrated by Nb2C, Ti2C, and Ti3C2, respectively. The etching of Al from the Nb2AlC, Ti2AlC, and Ti3AlC2 MAX phases leads to an enhanced surface area, which improves the photodegradation performance. The findings align with the SEM pictures, which unequivocally demonstrate the strong gaps formed by etching the middle layer of their predecessor MAX phases. As a result, Nb2C, Ti2C, and Ti3C2 MXenes can be suggested as a very efficient and rapid catalyst to address significant environmental pollution issues.

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Limited by insufficient active sites and restricted mechanical strength, designing reliable and wearable gas sensors with high activity and ductility remains a challenge for detecting hazardous gases. In this work, a thermally induced and solvent-assisted oxyanion etching strategy was implemented for selective pore opening in a rigid microporous Cu-based metal-organic framework (referred to as CuM). A conductive CuM/MXene aerogel was then self-assembled through cooperative hydrogen bonding interactions between the carbonyl oxygen atom in PVP grafted on the surface of defect-rich Cu-BTC and the surface functional hydroxyl group on MXene. A flexible NO2 sensing performance using the CuM/MXene aerogel hybridized sodium alginate hydrogel is finally achieved, demonstrating extraordinary sensitivity (S = 52.47 toward 50 ppm of NO2), good selectivity, and rapid response/recovery time (0.9/4.5 s) at room temperature. Compared with commercial sensors, the relative error is less than 7.7%, thereby exhibiting significant potential for application in monitoring toxic and harmful gases. This work not only provides insights for guiding rational synthesis of ideal structure models from MOF composites but also inspires the development of high-performance flexible gas sensors for potential multiscenario applications.

Effective adsorption doxorubicin drug from aqueous system was achieved by utilizing a surface functionalized, two-dimensional transition metal carbide (MXene). Synthesis of impurity-free parent phase, subsequent etching and alkalization produced surface...

The effect of 1030nm single picosecond pulsed laser-induced modification of the bulk of crystalline sapphire using a combined process of laser amorphization and selective wet chemical etching is studied. Pulse durations of more than 1 picosecond are not commonly used for this subsurface process. We examine the effect of 7 picosecond pulses on the morphology of the unetched, as well as etched, single pulse modifications, showing the variation of shape and size when varying the pulse energy and the depth of processing. In addition, a qualitative analysis of the material transformation after irradiation is provided as well as an analysis of cracking phenomena. Finally, a calculated laser intensity profile inside sapphire, using the Point Spread Function (PSF), is compared to the shape of the modifications. This comparison is employed to calculate the intensity threshold leading to amorphization, which equals 2.5⋅1014 ± 0.4⋅1014 W/cm2.

Two-dimensional (2D) MXene materials with innovative properties and versatile applications have gained immense popularity among scientists. The green and environmentally friendly Lewis acid salt etching route has opened up immense possibilities for the advancement of 2D MXene materials. In this study, we precisely etched the Al element from the double A-element MAX phases Ti2(SnyAl1-y)C by employing Lewis molten salt guided by redox potentials. This approach led to the discovery of a novel Ti2SnyCClx dual-phase structure consisting of Ti2SnC and Ti2CClx. We then established that the etching of the MAX phase via Lewis acid salt is facilitated by the oxidation of M-site elements, with the MX sublayer acting as an electron transmission conduit to enable the oxidation of A-site elements. This work is dedicated to unraveling the underlying mechanisms governing the etching processes using Lewis molten salt, thereby contributing to a more profound comprehension of these innovative etching routes.

We explore the origin of inequivalent etching on equivalent crystal sites by developing a kinetic Monte Carlo model. This new model focuses on the effects of both the diffusion of reactants and ligands, factors that are ubiquitous in wet-chemistry experiments and yet often overlooked or oversimplified in conventional simulations, where the defaults are rapid reactant redistribution and rapid equilibration of ligand adsorption/desorption. Our results show the dramatic differences arising from non-equilibrium ligand control, which cause selective etching at the corners, edges, or facets of Au triangular nanoplates. Basically, the ligand effects provide a positive feedback when etching targets the ligand-deficient sites, and the newly exposed atoms are ligand-free. In contrast, slow reactant diffusion provides a negative feedback, as a reactive site cannot etch unrestrictedly due to the lack of reactants. The dynamic competitions are clearly manifested in the focused etching mode when ligand effects coincide with large diffusion rates. By appropriately setting these two crucial factors, we reproduce in silico a series of etching products that are fully consistent with previous experimental results, along with the details in the shape of notches at the edges and holes on the plane. We believe that our simulation model could be expanded to many other systems and provide detailed inner workings for the mechanisms of abnormal crystal morphologies.

The change in ion energy distribution and composition of a reactive ion beam produced by an RF-excited ion beam source and operation with a mixture of CHF3 and O2 was investigated and correlated with the etching behavior. To this end, measurements were performed with an energy-selective mass spectrometer to determine ion energy distributions, current density measurements for the measurement of current density distributions of the ion beam, and tactile measurements to determine the etching rates of Si and photoresist. The morphology of the photoresist was measured with a scanning force microscope. In particular, alterations in the etching yield and surface morphology of the photoresist can be observed in response to changes in the applied RF-power. An increase in plasma density leads to an increase in fragmentation processes of the injected reactive gases, resulting in the formation of smaller fragments. These smaller fragments have a chemical impact on the substrate surface, which affects the etching performance. These effects can have significant consequences in the context of long-time reactive ion beam processing for patterning applications.

Silicon is considered an attractive active anode material for lithium‐ion batteries because of its high theoretical capacity and abundance. However, the application of silicon anodes is hindered by their large volume changes during charge–discharge cycles and low conductivity. Herein, structural design is focused and a scalable method is developed for producing porous Si electrodes with excellent electrochemical characteristics and cycle properties. Al72.5Si25Ti2.5 powders with fine solidification structures are produced using the gas atomization method, and porous Ti(Al,Si)2@Si particles with uniform silicon frameworks are synthesized by leaching Al in the atomized powder precursor using hydrochloric acid. The porous Ti(Al,Si)2@Si particles show a pore size distribution of 50–200 nm and demonstrate excellent rate characteristics with a capacity of 1683 mAh g−1 after 100 cycles, a Coulombic efficiency of >97%, and high stability. The particles maintain discharge capacity at a constant charge capacity of 1000 mAh g−1 at 0.2 C for up to 1000 cycles without degradation. The pores elicit a buffer effect that suppresses volume expansion during lithium insertion while the Ti(Al,Si)2 silicide phase improves the electrical conductivity, improving rate and cycle performances.

In this study, a simple method involving immersion and heat treatment was used to modify graphite felt, enabling the attachment of Co 3 O 4 and altering its morphology. The etching process created nanorod structures, which significantly increased the surface area and improved wettability. A Co(NO 3 ) 2 concentration of 4 m m demonstrated optimal electrochemical activity compared to pristine graphite felt. Following the modification, the electrochemically active surface area reached a high value of 131.71 cm 2 , the charge transfer resistance decreased to 12.27 Ω, and the exchange current density increased to 25.02 mA/cm 2 . Cyclic voltammetry measurements revealed that GF4 exhibited reversible redox activity across various scan rates and maintained stability over 50 cycles at a scan rate of 1.0 mV/s, with I pa / I pc  = 1.18 and ∆ E p  = 220 mV. These findings indicate that the modification method improves the performance of graphite felt cathodes in vanadium redox flow batteries, emphasizing its potential for energy storage.

MXenes, represented by Ti3C2Tx, have been widely studied in the electrochemical energy storage fields, including lithium-ion batteries, for their unique two-dimensional structure, tunable surface chemistry, and excellent electrical conductivity. Recently, Nb2CTx, as a new type of MXene, has attracted more and more attention due to its high theoretical specific capacity of 542 mAh g-1. However, the preparation of few-layer Nb2CTx nanosheets with high-quality remains a challenge, which limits their research and application. In this work, high-quality few-layer Nb2CTx nanosheets with a large lateral size and a high conductivity of up to 500 S cm-1 were prepared by a simple HCl-LiF hydrothermal etching method, which is 2 orders of magnitude higher than that of previously reported Nb2CTx. Furthermore, from its aqueous ink, the viscosity-tunable organic few-layer Nb2CTx ink was prepared by HCl-induced flocculation and N-methyl-2-pyrrolidone treatment. When using the organic few-layer Nb2CTx ink as an additive-free anode of lithium-ion batteries, it showed excellent cycling performance with a reversible specific capacity of 524.0 mAh g-1 after 500 cycles at 0.5 A g-1 and 444.0 mAh g-1 after 5000 cycles at 1 A g-1. For rate performance, a specific capacity of 159.8 mAh g-1 was obtained at a high current density of 5 A g-1, and an excellent capacity retention rate of about 95.65% was achieved when the current density returned to 0.5 A g-1. This work presents a simple and scalable process for the preparation of high-quality Nb2CTx and its aqueous/organic ink, which demonstrates important application potential as electrodes for electrochemical energy storage devices.

Development of high-performance metal sulfides anode materials is a great challenge for sodium-ion batteries (SIBs). In this work, a cobalt-based imidazolate framework (ZIF-67) were firstly synthesized and applied as precursor. After the successive surface etching, ion exchange and sulfidation processes, the final cobalt-vanadium sulfide yolk-shell nanocages were obtained (CoS2/VS4@NC) with VS4 shell and CoS2 yolk encapsulated into nitrogen doped carbon frameworks. This yolk-shell nanocage structure effectively increases the specific surface area and provides enough space for inhibiting the volume change during charge/discharge processes. Besides, the nitrogen doped carbon skeleton greatly improves the ionic conductivity and facilitates ion transport. When used as the anode materials for SIBs, the yolk-shell nanocages of CoS2/VS4@NC electrode exhibits excellent rate capability and stable cycle performance. Notably, it displays a long-term cycling stability with excellent capacity of 417.28 mA h g-1 after 700 cycles at a high current density of 5 A/g. This developed approach here provides a new route for the design and synthesis of various yolk-shell nanocages nanomaterials from enormous MOFs with multitudinous compositions and morphologies and can be extended to the application into other secondary batteries and energy storage fields.

Electrochemical nitrite reduction reaction (NO2RR) is considered as a sustainable ammonia (NH3) synthesis strategy. However, there are still significant challenges in designing efficient NO2RR catalysts. Here, carbon nanotube (CNT) encapsulated Ni nanoparticles (NPs) loaded on MXene-derived TiN (Ni@TiN/CNT) heterostructure is constructed by combining molten salt etching strategy and chemical vapor deposition. Ni@TiN/CNT exhibits excellent NH3 yield rate (15.6 mg h-1 mgcat.-1), Faradaic efficiency (95.6%) and record cycle stability (NO2RR performance is virtually unattenuated after 60 cycles) at -0.7 V versus reversible hydrogen electrode (vs. RHE). In addition, the Zn-nitrite battery with Ni@TiN/CNT as the cathode shows high power density (9.6 mW cm-2) and NH3 synthesis performance. Combining validation experiments and density functional theory calculations reveal that Ni@TiN/CNT follows the tandem catalytic mechanism. The TiN site preferentially adsorbs and activates NO2-, while the Ni site provides abundant active hydrogen for the subsequent reduction process. Meanwhile, the chainmail structure of CNT prevents the oxidation and leaching of active sites, thereby significantly enhancing the stability of Ni@TiN/CNT. This work provides a new inspiration for the preparation of durable and efficient NO2RR electrocatalysts with tandem catalytic sites.

In this study, the electrochemical energy storage properties of Ti3C2Tx MXene films have been improved by the addition of W1.33CTz MXenes with ordered vacancies in their structure. The W1.33CTz i-MXene was obtained from the (W2/3Y1/3)2AlC i-MAX phase by etching in a HCl/LiF mixture under hydrothermal conditions followed by delamination by the intercalation of tetramethylammonium ions. Ti3C2Tx/W1.33CTz composite electrode films were prepared from colloidal solutions, which were mixed in an appropriate ratio to achieve the W1.33CTz concentrations of 10, 20, 30 and 40 wt%. MXenes were characterized by XRD, SEM, TEM and XPS methods. The electrochemical energy storage properties of binder-free MXene films were studied by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) methods. It has been shown that the addition of 20 wt% W1.33CTz can significantly improve the pseudocapacitive intercalation of electrolyte ions. The specific capacitance of Ti3C2Tx/W1.33CTz (20 wt%) electrodes in H2SO4, LiCl and KOH electrolytes was 375, 171 and 235 F g-1, respectively, at a scan rate of 5 mV s-1. The composite electrode showed good cycling stability (more than 93% capacity retention after 10 000 cycles). The results obtained indicated that the synthesised composite could be considered a promising electrode material for energy storage systems.

The ability to vary the temperature of an electrochemical cell provides opportunities to control reaction rates and pathways and to drive processes that are inaccessible at ambient temperature. Here, we explore the effect of temperature on electrochemical etching of Ni–Pt bimetallic nanoparticles. To observe the process at nanoscale resolution we use liquid cell transmission electron microscopy with a modified liquid cell that enables simultaneous heating and biasing. By controlling the cell temperature, we demonstrate that the reaction rate and dissolution potential of the electrochemical Ni etching process can be changed. The in situ measurements suggest that the destabilization of the native nickel oxide layer is the slow step prior to subsequent fast Ni removal in the electrochemical Ni dissolution process. These experiments highlight the importance of in situ structural characterization under electrochemical and thermal conditions as a strategy to provide deeper insights into nanomaterial transformations as a function of temperature and potential.

Corrosion engineering is an efficient strategy to achieve durable oxygen evolution reaction (OER) catalysts at high current densities beyond 500 mA cm-2. However, the spontaneous electrochemical corrosion has a slow reaction rate, and most of them need to add large amounts of salts (such as NaCl) to accelerate the corrosion process. In this report, a novel and effective phytic acid (PA)-assisted in situ electrochemical corrosion strategy is demonstrated to accelerate the the corrosion process and form bimetallic active catalysts to show excellent OER performance at large current densities. In situ rapid electrochemical corrosion of nickel foam substrate and PA ligands etching realize localized high concentrations of Ni and Fe ions. High concentrations of metal ions will combine with hydroxyl to effectively form defects-enriched NiFe layered double hydroxides porous nanosheets tightly anchoring on the underneath substrate. Remarkably, the activated electrode exhibits excellent OER catalytic activities with ultralow overpotentials of 289 and 315 mV to reach high current densities of 500 and 1000 mA cm-2, respectively. When coupled with Ni-Mo-N hydrogen evolution reaction catalysts, the two-electrode cell merely requires 1.87 V to deliver 1000 mA cm-2. The ligands-assisted rapid electrochemical corrosion strategy provides a fresh perspective for facile, cost-effective, and scale-up production of superior OER catalysts at large current densities.

No abstract available

Vacancies play a pivotal role in determining the physical and chemical properties of materials. Introducing vacancies into two‐dimensional (2D) materials offers a promising strategy for developing high‐performance electrode materials for electrochemical energy storage. Herein, a facile top‐down strategy is employed to create V‐based MXenes with tunable vacancy concentrations, achieved by designing the precursor (V 1−x Cr x ) 2 AlC (x = 0.05, 0.1, 0.3) MAX phase and precisely controlling the etching process. Systematic investigations reveal that introducing a moderate concentration of Cr‐induced vacancies significantly enhances both the capacitance and rate performance of V‐based MXenes. Specifically, V 1.9 CT z achieves a capacitance of 760 F g −1 , far exceeding the 420 F g −1 of vacancy‐free V 2 CT z MXene. In contrast, an excessively high vacancy concentration leads to deteriorated electrochemical performance and compromised structural stability. This work illustrates that defect engineering is a powerful approach to tailor the electrochemical properties of MXenes, offering a framework for designing next‐generation MXene‐based energy storage systems.

It is still challenging to develop an effective strategy to simultaneously enhance the activity and stability of electrocatalysts for electrocatalytic nitrate reduction reaction (eNO3RR). Herein, taking metallic cobalt as an example, it is demonstrated that the construction of low-coordinated cobalt nanosheets (L-Co NSs) by H2 plasma etching of electrodeposited cobalt nanosheets (Co NSs) can greatly enhance the activity and stability of metallic cobalt for eNO3RR. Compared with Co NSs, at -0.4 V versus RHE, the nitrate removal rate, ammonia partial current density, and ammonia yield are increased by L-Co NSs from 82.14% to 98.57%, from 476 to 683 mA cm-2, and from 2.11 to 2.54 mmol h-1 cm-2, respectively. In addition, L-Co NSs demonstrate negligible activity decay after 30 cycles of stability test, while the Co NSs show significant activity decline. In situ electrochemical characterizations and theoretical calculations verify that the abundance of Co vacancies in L-Co NSs not only contribute to the optimized electronic structure and enhanced desorption of key intermediate to boost the activity but also facilitate the transformation of Co(OH)2 to Co0 to promote the stability. Furthermore, L-Co NSs exhibit favorable performance in removing nitrate from simulated wastewater and air plasma discharge-electrocatalytic reduction cascade system to produce ammonia.

Zn metal anode is desired for aqueous batteries due to its high capacity and low redox potential. However, uneven Zn deposition and hydrogen evolution reaction (HER) have hindered the electrochemical reversibility and stability. Herein, an artificial solid electrolyte interphase (SEI) composed of metal center incorporated siloxane coupling with fluoride is in situ generated on Zn surface by a facile “etching–coating” process. This SZ‐SEI provides interaction sites with Zn2+, which helps with its desolvation at the interface and enlarges the transference number. Uniform Zn deposition underneath the layer is thus realized. Meanwhile, the SZ‐component hinders the adsorption of hydrogen atom and effectively suppresses HER. Thanks to the above effects, the cycle life of symmtric cells with SZ‐Zn electrodes extends to 2200 and 1400 h at the current densities of 10 and 20 mA cm−2, respectively. The coulombic efficiency of Zn plating/stripping also reaches 99.8% for 3800 cycles. In addition, the SZ‐Zn anode enables better rate capability and cycling stability of full cells.

Separators have directly affected the safety and electrochemical performance of lithium-ion batteries. In this study, an alkali etched enhanced polyimide (PI)/polyacrylonitrile (PAN)@ cellulose acetate (CA)/PI three-layer composite separator is prepared using electrospinning, non-solvent phase separation, and alkali etching methods. The effects of alkali etching on the mechanical strength, thermal stability, and electrochemical performance of the PI/PAN@CA/PI separator are explored. The obtained separator has two different pore structures, and the surface of the alkali etched separator has abundant polar groups, further enhancing the migration rate of lithium-ions. The mechanical strength and thermal performance decrease with the prolongation of alkali etching time. When the alkali etching time is 3 min, the PI/PAN@CA/PI separator has the best comprehensive performance, with a mechanical strength of 17.8 MPa, ion conductivity of 1.22 mS cm−1, and interface impedance of 152 Ω. After 100 cycles of charging and discharging at a current density of 1 C, the capacity retention rate is 95.3%. At a current density of 5 C, the specific capacity of charging and discharging can reach 114 mAh g−1, which is better than the 87.3 mAh g−1 of the initial PI/PAN@CA/PI separator.

No abstract available

To overcome the significant volume expansion issue encountered by traditional silicon anodes in lithium‐ion batteries, this study employs chemical etching techniques to treat aluminum–silicon alloys of various ratios, successfully preparing three types of porous silicon electrode materials with different pore structures. Through a series of electrochemical tests, this article investigates the role of porous silicon structures in improving electrode performance. The results demonstrate that the porous silicon anodes exhibit superior cycle stability and rate capability compared to traditional solid silicon anodes. This confirms the effectiveness of the porous structure in mitigating the significant volume expansion during the charge and discharge process of silicon materials and in preventing premature electrode failure, thereby significantly enhancing the electrode's cycle life. Remarkably, the porous silicon with a high porosity rate shows exceptionally outstanding performance. Additionally, using computer simulations, this study also models the impact of changes in pore size within the porous silicon material at different states of charge and discharge on the stress distribution at the particle center and surface. These experimental and simulation results jointly provide strong empirical evidence for applying porous silicon materials as high‐performance anode materials for lithium‐ion batteries and offer essential guidance for future stress analysis and electrode design of porous silicon electrode materials.

In the generation of green hydrogen and oxygen from water, transition metal–based electrode materials have been considered high‐performance water‐splitting catalysts. In water splitting, the oxygen evolution reaction (OER) is the rate‐determining step. To overcome the high overpotential and slow kinetics of OER, the development of effective catalysts to improve electrolysis efficiency is essential. Nickel–iron‐layered double hydroxides (NiFe‐LDHs) have been recognized for their superior electrochemical performance under alkaline OER conditions and have emerged as promising catalysts owing to their unique structure that enhances electrolyte infiltration and exposes more active sites. However, the unique modulation of the crystalline structure of NiFe‐LDHs can further improve OER performance. Accordingly, this study introduces an innovative synthesis approach based on Zn doping and selective Zn etching to increase the ECSA and induce favorable transition‐metal oxidation states in NiFe‐LDHs, thereby improving OER efficiency. After 6 h of Zn etching (Ni2.9Zn0.1Fe‐6h), the optimized Ni2.9Zn0.1Fe LDH sample demonstrated remarkable electrochemical performance and stability, requiring small overpotentials of 192 and 260 mV at current densities of 10 and 100 mA cm−2, respectively. Moreover, the Ni2.9Zn0.1Fe‐6h electrode could maintain its original overpotential (260 mV) at a current density of 100 mA cm−2 for 250 h. The proposed Zn doping and subsequent partial Zn etching can practically be applied to numerous high‐performance transition metal–based electrochemical catalysts.

Abstract To promote the rapid development of high-performance energy storage devices, graphene quantum dots (GQDs) have attracted extensive attention due to their excellent properties such as high electrical conductivity, high specific surface area, high mobility and good dispersion in various solvents. Here, the solid-state on-chip planar micro-supercapacitors (PMSCs) based on the GQDs were facilely assembled by liquid-air interface self-assembly, photolithography, oxygen plasma etching and gold sputtering. The fabricated PMSCs delivered an area capacitance of 2.83 µF cm−2, an energy density of 0.40 nWh cm−2 and a power density of 49.64 µW cm−2. The PMSCs allowed for operation at the scan rate up to 10,000 V s−1, indicating ultrahigh rate capability, and had the relaxation time constant of 197 µs, revealing excellent frequency response capability and the retention of initial specific capacitance of about 94% after 10,000 cycles at the scan rate of 500 V s−1, demonstrating good sustainable electrochemical stability. This work paves the way for new prospective applications of the GQDs in the portable-wearable micro-nano energy storage field.

No abstract available

In-situ synthesized hollow transition metal chalcogenides have gained significant attention on account of their excellent electrochemical properties. Here, Ni-doped V-MOF (V(Ni)-MOF) nanorod arrays as precursor are first grown on nickel foam (NF). Subsequently, the nanorod arrays are converted into V(NiCo)-OH hollow nanotube arrays with cross-linked nanosheets by Co2+ etching. Finally, V(NiCo)-OH/NF is converted into V(NiCo)-X/NF (X = O, S and Se) by annealing or ion exchange. Due to the unique morphology of hollow nanotube arrays with cross-linked nanosheets and synergistic effect of multi-metal components, the V(NiCo)-Se/NF achieves an outstanding specific capacity (1806.7 C g-1 at 1 A g-1), which is higher than that of V(NiCo)-O/NF (1208.3 C g-1) and V(NiCo)-S/NF (1558.4 C g-1). In addition, the capacity retention rate is 91.7 % (at 10 A g-1 after 10, 000 cycles). Utilizing V(NiCo)-Se/NF (positive) and activated carbon/NF (negative), the hybrid supercapacitor (HSC) achieves an impressive high energy density of 114.8 Wh kg-1 (at 679.5 W kg-1). Moreover, two HSCs in series can power the LED and stopwatch, and keep working for more than 60 min, displaying good practical application capabilities.

In situ etching and co-growth of ultra thin defect-rich oxide layers on porous silicon. Through the construction of nano-sized catalytic interface, the electrolyte addition FEC would decompose to a LiF-rich solid electrolyte interphase (SEI). The robust SEI on porous structured silicon performs high-rate stability at varied temperatures. In situ etching and co-growth of ultra thin defect-rich oxide layers on porous silicon. Through the construction of nano-sized catalytic interface, the electrolyte addition FEC would decompose to a LiF-rich solid electrolyte interphase (SEI). The robust SEI on porous structured silicon performs high-rate stability at varied temperatures. Silicon stands as a key anode material in lithium-ion battery ascribing to its high energy density. Nevertheless, the poor rate performance and limited cycling life remain unresolved through conventional approaches that involve carbon composites or nanostructures, primarily due to the un-controllable effects arising from the substantial formation of a solid electrolyte interphase (SEI) during the cycling. Here, an ultra-thin and homogeneous Ti doping alumina oxide catalytic interface is meticulously applied on the porous Si through a synergistic etching and hydrolysis process. This defect-rich oxide interface promotes a selective adsorption of fluoroethylene carbonate, leading to a catalytic reaction that can be aptly described as “molecular concentration-in situ conversion”. The resultant inorganic-rich SEI layer is electrochemical stable and favors ion-transport, particularly at high-rate cycling and high temperature. The robustly shielded porous Si, with a large surface area, achieves a high initial Coulombic efficiency of 84.7% and delivers exceptional high-rate performance at 25 A g−1 (692 mAh g−1) and a high Coulombic efficiency of 99.7% over 1000 cycles. The robust SEI constructed through a precious catalytic layer promises significant advantages for the fast development of silicon-based anode in fast-charging batteries.

Metal thiophosphite has demonstrated promising application potential as an anode material for sodium‐ion batteries. Nevertheless, the intrinsic low electrical conductivity and drastic volume expansion impede its commercialization. Herein, a series of metal thiophosphite/Ti3C2Tx (metal = Fe, Ni, Co, and Cd) composites are constructed via Lewis acidic molten salt etching followed by synchronous phospho‐sulfurization. The Ti3C2Tx substrate endows the thiophosphite/Ti3C2Tx hybrids with high electrical conductivity. Importantly, thiophosphite grown on the MXene layers exhibits a 3D cross‐linked structure, which not only facilitates electron/ion transport, but also maintains robust structural stability owing to the space confinement effect. As a proof of concept, FePS3/Ti3C2Tx demonstrates remarkable rate performance (827.4 and 598.1 mAh g−1 at 0.1 and 10 A g−1, respectively) along with long‐term cycling stability (capacity retention of 93.7% after 2000 cycles at 5 A g−1). Impressively, the FePS3/Ti3C2Tx//NVPO full cell exhibits a high reversible capacity of 396.8 mAh g−1 over 1350 cycles at 2 A g−1. The sodium storage mechanism of FePS3/Ti3C2Tx anode is further unveiled through in situ XRD/ex situ HRTEM characterizations and theoretical calculations. This work provides a fresh perspective on enhancing the electrochemical performance of thiophosphite through the in situ construction of thiophosphite/Ti3C2Tx hybrids.

Scandium antimony telluride (Sc-Sb-Te), a promising nonvolatile cache-type phase-change memory (PCM) material, exhibits remarkable characteristics such as ultrafast crystallization speed, commendable amorphous thermal stability, and minimal resistance drift. In order to attain large-capacity storage and high-parallel computing capabilities, the construction of high-density memory arrays composed of nano-scaled PCM cells employing the Sc-Sb-Te material is not only essential but also inevitable. Dry etching methodologies represent the mainstream approach in this regard, while the conventional process employing the fluorine-based reactive atmosphere, which has been effectively implemented on Ge-Sb-Te-like PCM materials, induces substantial cross-sectional damages and interfacial residues within the etched Sc0.3Sb2Te3 thin film. Here, we develop and optimize the chlorine-based dry etching techniques to address the issue, achieving low-damage and sharp sidewall etching morphologies, thanks to the reduction of chlorine element residue and the formation of volatile scandium chloride products. Our work offers a valuable technological guideline for the nanofabrication procedures involved in the production of ultra-scaled, high-density Sc-Sb-Te-based PCM chips.

Two-dimensional (2D) MoS2 is a promising material for future electronic and optoelectronic applications. 2D MoS2 devices have been shown to perform reliably under irradiation conditions relevant for a low Earth orbit. However, a systematic investigation of the stability of 2D MoS2 crystals under high-dose gamma irradiation is still missing. In this work, absorbed doses of up to 1000 kGy are administered to 2D MoS2. Radiation damage is monitored via optical microscopy and Raman, photoluminescence, and X-ray photoelectron spectroscopy techniques. After irradiation with 500 kGy dose, p-doping of the monolayer MoS2 is observed and attributed to the adsorption of O2 onto created vacancies. Extensive oxidation of the MoS2 crystal is attributed to reactions involving the products of adsorbate radiolysis. Edge-selective radiolytic etching of the uppermost layer in 2D MoS2 is attributed to the high reactivity of active edge sites. After irradiation with 1000 kGy, the monolayer MoS2 crystals appear to be completely etched. This holistic study reveals the previously unreported effects of high-dose gamma irradiation on the physical and chemical properties of 2D MoS2. Consequently, it demonstrates that radiation shielding, adsorbate concentrations, and required device lifetimes must be carefully considered, if devices incorporating 2D MoS2 are intended for use in high-dose radiation environments.

The performances of catalysts are highly dependent on their crystallinities. It is a significant challenge to successively manipulate the crystallinities of noble metal nanocatalysts due to the strong metallic bonds, especially under ambient conditions. Herein, a post-crystallization approach is developed for successive control of the crystallinity of Pd nanosheets via selective oxidation etching of the amorphous domains. This strategy can be extended to crystallize other Pd and Ru nanomaterials. By carefully modulating the crystallinity of Pd nanosheets, the time for the complete conversion of 4-nitrostyrene via hydrogenation is reduced by 20 times. Also, crystallization can turn the selectivity of the products and improve the stability of Pd nanosheets. These findings may advance the crystal engineering of metal nanomaterials for wide applications.

Large-area 3ω anti-reflection periodic nanostructure devices have been prepared on the surface of fused quartz by HF etching, EBL, step-and-flash Nanoimprint and ICP etching. It exhibits excellent transmissivity, environmental stability and Laser-induced Damage Threshold.

This paper investigates the effects of different polysilicon etching powers on the electric characteristics of low temperature polycrystalline silicon (LTPS) thin‐film transistors (TFTs). The study reveals that lower etching powers result in a weaker hump effect in the TFT Id‐Vg curves. The influence is more pronounced in TFTs with narrower channel widths. Despite minimal differences in the taper of polysilicon film after dry etching with different powers, the stability of TFTs under positive bias temperature stress (PBTS) degrades with increasing dry etching power, indicating that plasma intensity may induce damage to the edge of the polysilicon channel. When the etching power is reduced from 18 kW to 9 kW, the Vth shift is reduced by 25% after 10000 s PBTS at 70 °C. This results could lay the foundation for achieving high‐reliability flexible backplane for AMOLEDs.

This study focuses on the optimization of the dry etching process of single-layer metal films and focuses on the application of inductively coupled plasma (ICP) etching technology in bottom-top contact indium tin-zinc oxide (ITZO) thin-film transistors (TFTs). The effects of ICP etching time and gas pressure on device performance were analyzed by dry etching of the Mo metal source leakage electrode of ITZO TFT using Ar/SF6 as the etching gas. The experimental results show that the continuous increase in air pressure will aggravate the damage of the channel and induce the formation of trap state, resulting in an increase in threshold voltage and a decrease in mobility. Based on the above studies, the optimal etching conditions were identified, and these transistors exhibited excellent electrical characteristics, including a switching current ratio of approximately 109, a mobility of 60.25 cm2/Vs, and a subthreshold swing of 0.29 V/dec. It provides a process reference for improving the electrical performance stability of ITZO TFT devices.

The global rise of antimicrobial resistance (AMR) underscores the urgent need for novel antibacterial agents, particularly those based on two-dimensional (2D) nanomaterials, such as graphene oxide (GO). In this study, GO was synthesized from graphite using an improved Hummer's method optimized for scalability, safety, and environmental sustainability. The protocol eliminates hazardous sodium nitrate and substitutes highly corrosive sulfuric acid with milder phosphoric acid, which serves dual roles as an oxidizing and intercalating agent. This facilitates edge and surface etching, resulting in an oxo-functionalized GO with high aqueous stability and uniform dispersion. The antibacterial efficacy of the synthesized GO was evaluated against two Gram-positive bacteria, Enterococcus faecalis (ATCC 29212) and Staphylococcus aureus (ATCC 29213). The concentration and time-dependent killing efficacy of GO demonstrated the rapid killing of 5 log10 CFU/mL bacterial cells at 200 μg/mL within 1 h. The biofilm eradication potential of GO was explored, where ∼92% reduction in biofilm cell viability was noted at 100 μg/mL against both bacteria. The oxidative stress induction was assessed by Ellman's assay, and a concentration-dependent loss of glutathione was noted up to 36.01% at 200 μg/mL. The membrane permeabilization ability was analyzed by the propidium iodide (PI) uptake assay, where significant permeabilization was observed at 50 μg/mL or higher. The antibacterial mechanisms were further corroborated by atomic force microscopy and scanning electron microscopy, which revealed the morphological distortions attributed by the nanoknife-like edges of GO. The hemolytic assay against mice red blood cells indicated minimum to negligible toxicity of GO when tested up to 400 μg/mL, confirming its safety toward mammalian cells. Overall, these findings reinforce the potential of this safely synthesized GO as a multifunctional nanomaterial with significant potential for biomedical applications like antimicrobial coatings and wound dressings and for environmental applications including water purification and disinfection.

Microprocessing of transparent and high-hardness materials such as technical glasses and crystals attracts more and more attention due to the optical and mechanical properties of mentioned materials. A notable example is sapphire-one of the most rigid materials having impressive mechanical stability, high melting point, and a wide transparency window reaching into the UV range, together with impressive laser-induced damage thresholds. Sapphire is highly desired in micro-optics and photonics or micromechanics. Nonetheless, the usage of this material is limited by the complicated 3D microfabrication of sapphire. However, femtosecond laser-based microprocessing techniques are a good alternative for sapphire processing. A remarkable example is Selective Laser etching (SLE) which allows the production of arbitrary shape structures out of glasses[1], [2]. This method includes nanogratings inscription in the volume of transparent material and subsequent etching of laser-processed material [3]. However, sapphire adoption of this technique is currently limited. Thus, we present research on C-cut crystalline sapphire microprocessing by using femtosecond radiation-induced SLE. In the presentation, we demonstrate a comparison between different wavelength radiation (1030 nm, 515 nm, 343 nm) usage for material modification and various etchants (hydrofluoric acid, sodium hydroxide, potassium hydroxide, and sulphuric and phosphoric acid mixture) comparison. Due to the inability to etch crystalline sapphire, regular SLE etchants, such as hydrofluoric acid or potassium hydroxide, have limited adoption in sapphire selective laser etching. Meanwhile, a 78% sulphuric and 22% phosphoric acid mixture at $270^{\circ}\mathrm{C}$ temperature is a good alternative for this process. We present the changes in the material after the separate processing steps. After comparing different processing protocols, the perspective is demonstrated for sapphire structure formation. In Fig 1. we show SLE-made structures out of 0.5 mm thickness c-cut sapphire, showing current possibilities to form high aspect ratio structures out of crystalline materials.

Si-based semiconductor devices are not suitable for stable operations in the aerospace environments. Among the ultra-wide bandgap semiconductor materials, gallium oxide (Ga2O3) is attracting attention as the next-generation material for high-power semiconductor devices in extreme condition beyond Si, owing to its large band gap of 4.5-5.3 eV, high breakdown electric fields of 7-10 MV/cm, excellent chemical and thermal stability and radiation hardness. Alpha gallium oxide (α-Ga2O3) has the largest bandgap (4.8-5.3 eV) and the highest breakdown electric fields (~10 MV/cm) among the five Ga2O3 polymorphs, which facilitates the application of α-Ga2O3 as a high power device. However, the research on etching technology for α-Ga2O3 is rare. Etching technology is a crucial step of device fabrication. Chemical etching is free from plasma-induced damage which leads to superior device performance compared with dry etching, and high throughput with low cost is beneficial to industrial implementations. Chemical stability of Ga2O3 hinders the effective reaction with most chemical etchants. However, the photo-enhanced inverse metal assisted chemical (I-MAC) etching, where a noble metal with a high work function is utilized as a catalyst under UV irradiation, has emerged as a candidate for the chemical etching of Ga2O3. Deep-UV irradiation generates electron-hole pairs (EHPs) in the uncovered region of Ga2O3, and the metal electrode withdraws carriers from the photo-generated EHPs. The holes that are accumulated in the uncovered region of Ga2O3 react with gallium ions which produce gallium fluoride (GaF3) in a reaction with Hydrofluoric acid (HF). The etching process continues as the oxidant re-oxidizes the metal. The etch rate can be controlled by various parameter, including concentration and temperature of the etchant. In this work, for the I-MAC etch of α-Ga2O3 on sapphire substrate grown by halide vapor phase epitaxy, Pt was deposited on α-Ga2O3. Etch rate and surface roughness were characterized by atomic force microscopy after each step of the I-MAC etch. The I-MAC etch using HF and potassium persulfate (K2S2O8) solution with 185-nm UV irradiation was performed at constant durations under different etchant temperature conditions. The etch rates obtained at each temperature condition were fitted with the Arrhenius plot to estimate the activation energy of 0.898 eV. The etch depth showed a linear increase with time and the etch rate exhibits a direct dependency on the temperature of the etchant, indicating that the I-MAC etching of α-Ga2O3 is an activation-controlled reaction. As the I-MAC etching proceeded, surface roughness of α-Ga2O3 showed a tendency to increase. The rate at which the surface roughness increased increased with raising the etchant temperature. In the case of Pt there was no significant difference in the surface roughness after etching. After the completion of the I-MAC etch, the remaining Pt can be removed using aqua regia. The I-MAC etch process of α-Ga2O3 can allow us to fabricate α-Ga2O3 without plasma-damage. Figure 1

Transparent and high-hardness materials have become the object of wide interest due to their optical and mechanical properties; most notably, concerning technical glasses and crystals. A notable example is sapphire—one of the most rigid materials having impressive mechanical stability, high melting point and a wide transparency window reaching into the UV range, together with impressive laser-induced damage thresholds. Nonetheless, using this material for 3D micro-fabrication is not straightforward due to its brittle nature. On the microscale, selective laser etching (SLE) technology is an appropriate approach for such media. Therefore, we present our research on C-cut crystalline sapphire microprocessing by using femtosecond radiation-induced SLE. Here, we demonstrate a comparison between different wavelength radiation (1030 nm, 515 nm, 343 nm) usage for material modification and various etchants (hydrofluoric acid, sodium hydroxide, potassium hydroxide and sulphuric and phosphoric acid mixture) comparison. Due to the inability to etch crystalline sapphire, regular SLE etchants, such as hydrofluoric acid or potassium hydroxide, have limited adoption in sapphire selective laser etching. Meanwhile, a 78% sulphuric and 22% phosphoric acid mixture at 270 °C temperature is a good alternative for this process. We present the changes in the material after the separate processing steps. After comparing different processing protocols, the perspective is demonstrated for sapphire structure formation.

Aqueous zinc ion batteries are often adversely affected by the poor stability of zinc metal anodes. Persistent water‐induced side reactions and uncontrolled dendrite growth have seriously damaged the long‐term service life of aqueous zinc ion batteries. In this paper, it is reported that a zinc sulfide with optimized electron arrangement on the surface of zinc anode is used to modify the zinc anode to achieve long‐term cycle stability of zinc anode. The effective active sites of the zinc metal anode surface are first significantly improved by a simple ultrasound‐assisted etching strategy, and then the in situ zinc sulfide interface phase further guides the zinc ion deposition behavior on the surface of the zinc metal anode. The zinc sulfide protective layer well regulates the interfacial electric field and the migration of Zn2+, thereby significantly promoting the homogenization of zinc ion flux to achieve dendrite‐free deposition. In addition, the aqueous zinc ion full cell assembled based on ZnS@3D‐Zn anode achieves better output performance in long‐term cycles. In summary, this work sheds light on the importance of reasonable interfacial modification for the development of dendrite‐free and stable zinc anode chemistry, which opens up a new path for promoting the development of zinc‐based batteries.

The recent development of liquid cell (scanning) transmission electron microscopy (LC-(S)TEM) has opened the unique possibility of studying the chemical behavior of nanomaterials down to the nanoscale in a liquid environment. Here, we show that the chemically induced etching of three different types of silica-based silica nanoparticles can be reliably studied at the single particle level using LC-(S)TEM with a negligible effect of the electron beam, and we demonstrate this method by successfully monitoring the formation of silica-based heterogeneous yolk–shell nanostructures. By scrutinizing the influence of electron beam irradiation, we show that the cumulative electron dose on the imaging area plays a crucial role in the observed damage and needs to be considered during experimental design. Monte-Carlo simulations of the electron trajectories during LC-(S)TEM experiments allowed us to relate the cumulative electron dose to the deposited energy on the particles, which was found to significantly alter the silica network under imaging conditions of nanoparticles. We used these optimized LC-(S)TEM imaging conditions to systematically characterize the wet etching of silica and metal(oxide)–silica core–shell nanoparticles with cores of gold and iron oxide, which are representative of many other core–silica–shell systems. The LC-(S)TEM method reliably reproduced the etching patterns of Stöber, water-in-oil reverse microemulsion (WORM), and amino acid-catalyzed silica particles that were reported before in the literature. Furthermore, we directly visualized the formation of yolk–shell structures from the wet etching of Au@Stöber silica and Fe3O4@WORM silica core–shell nanospheres.

No abstract available

Highlights What are the main findings? Neutral O2 does not alter the emission or structure of CsPbBr3 QD films even under UV illumination. Reactive oxygen species (ROS) cause rapid PL quenching and lifetime shortening. ROS create Br vacancies and Pb–O bonds, generating deep nonradiative traps. What are the implications of the main findings? Oxygen-induced degradation originates from activated oxygen, not molecular O2. Plasma processing conditions must be carefully controlled to avoid ROS damage. Strategies such as passivation and encapsulation can preserve perovskite stability. Abstract The chemical identity of oxygen species plays a decisive role in determining the optical stability of halide perovskite QD films. Here, real-time in situ spectroscopic monitoring, together with steady-state and time-resolved photoluminescence measurements, is utilized to differentiate the effects of molecular oxygen and plasma-activated oxygen species on CsPbBr3 QD films. The films maintain nearly unchanged emission intensity, spectral profile, and carrier lifetimes when stored in vacuum or exposed to molecular O2 even under UV illumination, demonstrating that neutral O2 exhibits minimal reactivity toward the [PbBr6]4− framework. In contrast, oxygen plasma generates highly reactive atomic and ionic oxygen species that induce rapid and spatially heterogeneous photoluminescence quenching. This degradation is attributed to Br− extraction, Br-vacancy formation, and subsequent Pb–O bond generation, which collectively introduce deep trap states and enhance nonradiative recombination. These findings clearly indicate that reactive oxygen species rather than molecular O2 are the dominant driver of oxygen-induced luminescence degradation, providing mechanistic insight and offering processing guidelines for the reliable integration of perovskite nanomaterials in optoelectronic devices.

Establishing reliable electrical contacts to atomically thin materials is a prerequisite for both fundamental studies and applications yet remains a challenge. In particular, the development of contact techniques for air-sensitive monolayers has lagged behind, despite their unique properties and significant potential for applications. Here, we present a robust method to create contacts to device layers encapsulated within hexagonal boron nitride (hBN). This method uses plasma etching and metal deposition to create 'vias' in the hBN with graphene forming an atomically thin etch-stop. The resulting partially fluorinated graphene (PFG) protects the underlying device layer from air-induced degradation and damage during metal deposition. PFG is resistive in-plane but maintains high out-of-plane conductivity. The work function of the PFG/metal contact is tunable through the degree of fluorination, offering opportunities for contact engineering. Using the in situ via technique, we achieve ambipolar contact to air-sensitive monolayer 2H-molybdenum ditelluride (MoTe2) with more than 1 order of magnitude improvement in on-current density compared to previous literature. The complete encapsulation provides high reproducibility and long-term stability. The technique can be extended to other air-sensitive materials as well as air-stable materials, offering highly competitive device performance.

Violet phosphorus (VP), a novel two-dimensional (2D) nanomaterial, boasts structural anisotropy, a tunable optical bandgap, and superior thermal stability compared with its allotropes. Its multifunctionality has sparked widespread interest in the community. Yet, the VP’s air susceptibility impedes both probing its intrinsic features and device integration, thus making it of urgent significance to unveil the degradation mechanism. Herein, we conduct a comprehensive study of photoactivated degradation effects on VP. A nitrogen annealing method is presented for the effective elimination of surface adsorbates from VP, as evidenced by a giant surface-roughness improvement from 65.639 nm to 7.09 nm, enabling direct observation of the intrinsic morphology changes induced by photodegradation. Laser illumination demonstrates a significant thickness-thinning effect on VP, manifested in the remarkable morphological changes and the 73% quenching of PL intensity within 160 s, implying its great potential for the efficient selected-area etching of VP at high resolution. Furthermore, van der Waals passivation of VP using 2D hexagonal boron nitride (hBN) was achieved. The hBN-passivated channel exhibited improved surface roughness (0.512 nm), reduced photocurrent hysteresis, and lower responsivity (0.11 A/W @ 450 nm; 2 μW), effectively excluding adsorbate-induced electrical and optoelectrical effects while disabling photodegradation. Based on our experimental results, we conclude that three possible factors contribute to the photodegradation of VP: illumination with photon energy higher than the bandgap, adsorbed H2O, and adsorbed O2.

The occurrence and development of inflammatory bowel diseases (IBDs) are inextricably linked to the excessive production of reactive oxygen species (ROS). Thus, there is an urgent need to develop innovative tactics to combat IBDs and scavenge excess ROS from affected areas. Herein, silicon hydrogen nanoparticles (SiH NPs) with ROS-scavenging ability were prepared by etching Si nanowires (NWs) with hydrogen fluoride (HF) to alleviate the symptoms associated with IBD by orally targeting the inflamed colonic sites. The strong reductive Si-H bonds showed excellent stability in the gastric and intestinal fluids, which exhibited efficient ROS-scavenging effects to protect cells from high oxidative stress-induced death. After oral delivery, the negatively charged SiH NPs were specifically adsorbed to the positively charged inflammatory epithelial tissues of the colon for an extended period via electrostatic interactions to prolong the colonic residence time. SiH NPs exhibited significant preventive and therapeutic effects in dextran sodium sulfate-induced prophylactic and therapeutic mouse models by inhibiting colonic shortening, reducing the secretion of pro-inflammatory cytokines, regulating macrophage polarization, and protecting the colonic barrier. As determined using 16S rDNA high-throughput sequencing, the oral administration of SiH NPs treatment led to changes in the abundance of the intestinal microbiome, which improved the bacterial diversity and restored the relative abundance of beneficial bacteria after the inflamed colon. Overall, our findings highlight the broad application of SiH-based anti-inflammatory drugs in the treatment of IBD and other inflammatory diseases.