镍铁MOFs综述：Structural Diversity and Ligand Effects及合成策略

金属有机骨架(MOFs)是由金属中心或团簇与有机配体组装而成的一类新型晶体多孔材料,具有比表面积大、孔隙率高、孔径均匀以及结构多样等优良特性,已被广泛应用于催化、吸附、传感、样品前处理以及色谱分离等领域。近年来MOFs在色谱分离领域的应用备受关注。与传统色谱固定相材料(如介孔二氧化硅、纳米粒子以及多孔层等)相比,MOFs具备灵活可调控的孔道尺寸和结构,能够实现对分子间相互作用的精确控制。此外,种类丰富多样的功能配体和拓扑结构拓宽了MOFs在分离领域的应用范围,有望实现更多类型复杂样品的分离分析。MOFs的这些独特优势使其非常适用于构建各类新型色谱固定相。迄今为止MOFs色谱固定相已展现出优异的分离效能,在色谱分离领域具有明显的优势和巨大的应用潜力。本文重点介绍了MOFs色谱固定相的构建方法及其在色谱分离应用中的最新研究进展,包括高效液相色谱(HPLC)、气相色谱(GC)以及毛细管电色谱(CEC)领域;针对现有的MOFs色谱固定相制备方法进行了归类总结,并简要探讨了各个方法的优缺点及发展方向;还总结了近年来MOFs色谱固定相的典型应用;最后,本文对MOFs色谱分离介质未来的研究重点及发展前景进行了展望,以期为先进MOFs色谱固定相的理性构建与应用提供参考。

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Designing easy and sustainable strategies for the synthesis of metal-organic frameworks (MOFs) from organic and inorganic wastes with the efficient removal of phosphate from water remains a challenge. The majority of the reported works have utilized costly precursors and nonsoluble ligands for the synthesis of MOFs. Herein, we have developed a low-cost, simple, and sustainable alternative approach using the coprecipitation method in water at room temperature for the synthesis of a new adsorbent-based trimetallic MOF. Poly(ethylene terephthalate) and stainless steel wastes were used as sources of water-soluble disodium terephthalate ligand and three metallic species (chromium, nickel, and iron salts) for the fabrication of trimetallic MOF (CrNiFe-MOF), respectively. The newly developed MOF demonstrates a superior space-time yield of 5760 g m-3 day-1, reaching a level allowing the industrialization production of this sustainable MOF. The scanning electron microscopy and adsorption studies revealed that the developed trimetallic MOF consists of aggregated nanoparticles and the presence of defective as well as mesoporous structures. This MOF showed an enhanced adsorption capacity of phosphate from real eutrophic water samples and higher stability in a range of pHs. The density functional theory calculations evidenced that the phosphate ions preferentially adsorb over H2O toward the metal oxo-trimers, with the adsorption energies increasing from H3PO4 to PO43- species in line with an improvement of the adsorption performance of CrNiFe-MOF when the pH increases, i.e., when HPO42- and PO43- become more predominant. These calculations also supported that the incorporation of Cr metal sites in the oxo-trimer is expected to boost the phosphate affinity of the MOF. Finally, our work provides an easy and eco-friendly approach for MOF designing to enhance phosphate removal from water.

Refining synthesis strategies for metal–organic framework (MOF)-based catalysts to improve their performance and stability in an oxygen evolution reaction (OER) is a big challenge. In this study, a series of nanostructured electrocatalysts were synthesized through a solvothermal method by growing MOFs and metal–triazolates (METs) on nickel foam (NF) substrates (named MET-M/NF, M = Fe, Co, Cu), and these electrocatalysts could be used directly as OER self-supporting electrodes. Among these electrocatalysts, MET-Fe/NF exhibited the best OER performance, requiring only an overpotential of 122 mV at a current density of 10 mA cm−2 and showing remarkable stability over 15 h. The experimental results uncovered that MET-Fe/NF underwent an in situ structural reconstruction, resulting in the formation of numerous iron/nickel (oxy)hydroxides with high OER activity. Furthermore, in a two-electrode water-splitting setup, MET-Fe/NF only required 1.463 V to achieve a current density of 10 mA cm−2. Highlighting its potential for practical applications. This work provides insight into the design and development of efficient MOF-based OER catalysts.

Nonprecious transition metal‐organic frameworks (MOFs) are one of the most promising precursors for developing electrocatalysts with high porosity and structural rigidity. This study reports the synthesis of high efficiency electrocatalysts based on S‐doped NiFeP. MOF‐derived S‐doped NiFeP structure is synthesized by a one‐step phosphorization process with using S‐doped MOFs as the precursor, which is more convenient and environment friendly, and also helps retain the samples’ framework. The oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance of the NiFeP catalysts can be improved after partially replacing P by S due to the tunable electronic structure. The optimized CCS‐NiFeP‐10 reaches a current density of 10 mA cm–2 for OER with an overpotential of 201 mV and outperforms most NiFe‐based catalysts. The S doping plays an important role in tuning the ΔG values for intermediates formation in Ni atoms to a suitable value and exhibits a pronouncedly improved the OER performance. CCS‐NiFeP‐20 sample presents excellent HER performance due to the d‐band center downshifting from the Fermi level. When the voltage of the electrolytic cell is 1.50 V, a current density of 10 mA cm–2 can be obtained. This strategy paves the way for designing highly active none‐noble metal catalysts.

Bimetallic-organic frameworks (bimetallic-MOFs) have broad capabilities owing to the synergistic properties of two metals in a single structure. In this regard, we prepared a bimetallic-MOF containing iron (Fe) and nickel (Ni) metals. The prepared bimetallic-MOF was functionalized with sulfonic acid groups via a post-modification method. Thus, a new acidic catalyst with special abilities was prepared. The physicochemical properties of the bimetallic-MOF containing sulfonic acid groups were investigated through FT-IR, SEM, BET/BJH, XRD, EDS, elemental mapping and TGA/DTG analyses. According to the acidic active sites in the structure of the presented catalyst, we investigated the performance of this catalyst in the synthesis of nicotinonitrile derivatives. The structure of the products was also confirmed using melting point, FT-IR, HR-mass, 1H-NMR, and 13C-NMR analyses. Moreover, the antibacterial properties of the synthesized product and MIL-88B(Fe2/Ni)/imidazole/SO3H were investigated, and results showed satisfactory antibacterial properties of these compounds against Gram-positive and Gram-negative bacteria.

Layered double hydroxides (LDHs) have been reported as one of the most effective materials for oxygen evolution reaction (OER) catalysts, which are prone to hydrolysis and oxidation under OER conditions. Metal–organic frameworks (MOFs) are porous materials with high crystallinity and internal surface area. The design of LDHs based on MOFs has attracted increasing attention owing to their high surface area, exposed catalysis sites, and fast charge/mass transport kinetics. Herein, we report a novel approach to fabricate a leaf-shaped iron-doped nickel–cobalt LDH (L-Fe-NiCoLDH) derived from a two-dimensional (2D) zeolitic imidazolate framework with a leaf-like morphology (ZIFL). Iron doping played a significant role in enhancing the specific surface area, affecting the OER performance. L-Fe-NiCoLDH showed high OER performance with an overpotential of 243 mV at 10 mA cm−2 and high durability after 20 h. The design of LDHs based on the leaf morphology of MOFs offers tremendous potential for improving OER efficiency.

Transition metal nitrides (TMNs) nanostructures possess distinctive electronic, optical, and catalytic properties, showing great promise to apply in clean energy, optoelectronics, and catalysis fields. Nonetheless, phase-regulation of NiFe-bimetallic nitrides nanocrystals or nanohybrid architectures confronts challenges and their electrocatalytic overall water splitting (OWS) performances are underexplored. Herein, novel pure-phase Ni2+ x Fe2- x N nanocrystals armored with amorphous N-doped carbon (NC) nanoparticles nanocubes (NPNCs) are obtained by controllable nitridation of NiFe-Prussian-blue analogues derived oxides/NC NPNCs under Ar/NH3 atmosphere. Such Ni2+ x Fe2- x N/NC NPNCs possess mesoporous structures and show enhanced electrocatalytic activity in 1 m KOH electrolyte with the overpotential of 101 and 270 mV to attain 10 and 50 mA cm-2 current toward hydrogen and oxygen evolution reactions, outperforming their counterparts (mixed-phase NiFe2 O4 /Ni3 FeN/NC and NiFe oxides/NC NPNCs). Remarkably, utilizing them as bifunctional catalysts, the assembled Ni2+ x Fe2- x N/NC||Ni2+ x Fe2- x N/NC electrolyzer only needs 1.51 V cell voltage for driving OWS to approach 10 mA cm-2 water-splitting current, exceeding their counterparts and the-state-of-art reported bifunctional catalysts-based devices, and Pt/C||IrO2 couples. Additionally, the Ni2+ x Fe2- x N/NC||Ni2+ x Fe2- x N/NC manifests excellent durability for OWS. The findings presented here may spur the development of advanced TMNs nanostructures by combining phase, structure engineering, and hybridization strategies and stimulate their applications toward OWS or other clean energy fields.

The catalytic performance of oxalate-based Ni-Fe metal-organic frameworks (MOFs) in the oxygen evolution reaction (OER) was investigated via a coordination strategy. The bidentate chelating ligand 2,2'-bpy (2,2'-bipyridine), was utilized to improve the catalytic kinetics under ambient conditions. The results revealed that a MOF-to-MOF transformation including the formation of [M(2,2'-bpy)n]2/3+ (M = Ni/Fe, n = 1-3) could boost alkaline OER, giving an impressive ultralow overpotential of 220 mV at a current density of 10 mA/cm2 in a 1 M KOH solution, surpassing the performance of control group activity of oxalate-based Ni-Fe MOF. However, excessive addition of the ligand had a negative effect, leading to decreased activity. Further investigation revealed the double role of 2,2'-bpy: Both promote and suppress catalytic reactions. The catalytic mechanism was then discussed, highlighting the potential of secondary ligands to effectively fine-tune the catalytic behavior of these materials.

Developing highly efficient, cost-effective, non-noble-metal-based electrocatalysts with superior performance and stability for oxygen evolution reactions is of immense challenge as well as great importance for the upcoming sustainable and green energy conversion technologies. The multivariate metal-organic frameworks with hierarchical porous structures and unsaturated coordination modes are considered to be promising emerging energy materials. In this work, a series of multimetallic MOFs were directly grown on nickel foam (NF) through the solvothermal method. Notably, the optimized tetrametallic FeCoNiMn-MOF/NF shows a low overpotential of 239 mV to achieve a current density of 50 mA cm-2 with a Tafel slope of 62.05 mV dec-1 for OER in 1 M KOH. It also exhibits excellent stability and durability over 100 h in chronoamperometric studies. The enhanced performance is closely tied to the high activity of iron and nickel ions and the decomposed and reconstructed Ni/Fe-OOH intermediates of the FeCoNiMn-MOF/NF during the OER process, which are revealed by XPS analysis and in situ Raman spectroscopy. This present work demonstrates the feasibility and advantage of utilizing highly efficient and durable multimetallic MOFs for electrocatalytic oxygen evolution.

Non-noble metal MOFs hold great potential for the alkaline oxygen evolution reaction (OER). In this work, cyano-bridged nickel-iron MOFs derived from pentacyanonitrosylferrate ([Fe(CN)5NO]2-) were fabricated to explore their feasibility as oxygen evolution electrocatalysts via coordination modulation with ethylenediamine (en). The structural evolution and structure-activity mechanism of the as-prepared Ni-Fe-MOF@(1:n)en (n = 1, 2, 3) coordination polymers were systematically investigated before and after the OER process. Interestingly, en effectively adjusts the dimensionality of cyano-bridged Ni-Fe moieties, transforming the initial 3D Prussian blue structure into one-dimensional metal chains. Upon compositing with carbon nanotubes (CNTs), the obtained material exhibits efficient OER catalytic activity (η10 = 290 mV at 10 mA·cm-2; Tafel slope = 55 mV·dec-1). Further studies reveal that the partial cleavage of Ni-NC bonds triggers surface reconstruction, generating highly active Ni(en)2OH-Fe(CN)5NO metal active units. This finding challenges the conventional view that cyano groups poison metal active sites and degrade catalytic performance. Density functional theory (DFT) calculations further confirm that the uniquely reconstructed structural unit can effectively optimize the adsorption-desorption kinetics of reaction intermediates. This work proposes a facile chelating ligand modulation strategy to regulate the structure and electrocatalytic properties of strongly coordinated non-noble metal MOFs.

A mixed-valence oxotrimer metal-organic framework (MOF), Ni-MIL-127, with a fully coordinated nickel atom and two iron atoms in the inorganic node, generates a missing linker defect upon thermal treatment in helium (>473 K) to engender an open coordination site on nickel which catalyzes propylene oligomerization devoid of any cocatalysts or initiators. This catalyst is stable for ∼20 h on stream at 500 kPa and 473 K, unprecedented for this chemistry. The number of missing linkers on synthesized and activated Ni-MIL-127 MOFs is quantified using temperature-programmed oxidation, 1H nuclear magnetic resonance spectroscopy, and X-ray absorption spectroscopy to be ∼0.7 missing linkers per nickel; thus, a majority of Ni species in the MOF framework catalyze propylene oligomerization. In situ NO titrations under reaction conditions enumerate ∼62% of the nickel atoms as catalytically relevant to validate the defect density upon thermal treatment. Propylene oligomerization rates on Ni-MIL-127 measured at steady state have activation energies of 55-67 kJ mol-1 from 448 to 493 K and are first-order in propylene pressures from 5 to 550 kPa. Density functional theory calculations on cluster models of Ni-MIL-127 are employed to validate the plausibility of the missing linker defect and the Cossee-Arlman mechanism for propylene oligomerization through comparisons between apparent activation energies from steady-state kinetics and computation. This study illustrates how MOF precatalysts engender defective Ni species which exhibit reactivity and stability characteristics that are distinct and can be engineered to improve catalytic activity for olefin oligomerization.

Ternary Prussian blue analogues (t-PBAs) containing nickel, manganese, and iron were synthesized via a facile aqueous coprecipitation method to investigate how Mn/Ni ratios influence structural and electrochemical properties. X-ray diffraction, combined with thermal and spectroscopic analyses, showed a systematic dependence of structural parameters on the manganese content, which also impacts the number of coordinated water molecules, suggesting a less defective Fe(CN)6 framework, and weakens the Fe–CN bond. The kinetics and thermodynamics of Ni2+ and Mn2+ ions in water during nucleation were correlated with ligand-exchange behavior, clarifying their impact on crystalline coherence. The presence of nickel was found to be the key to stabilizing the materials against changes induced by light irradiation and bias solicitation. Indeed, electrochemical measurements demonstrated that Ni-rich analogues exhibit superior stability and capacitance retention, whereas Mn-rich counterparts show an increased capacitive behavior but poorer cycling durability. These findings bridge coordination chemistry and solid-state physics in t-PBAs, providing design guidelines for mixed-metal frameworks with tunable properties.

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Abstract Two-dimensional (2D) coordination polymers, including metal-organic frameworks (MOFs) and infinite coordination polymers (ICPs), have been regarded as promising electrocatalysts. Although much effort has been devoted to investigating the electrocatalytic performance of MOFs, only a few reports are available on ICPs. Here, a facile room-temperature strategy has been developed to synthesize an iron-nickel amorphous ICP (Ni2Fe-ICP) nanosheet array on Ni foam as a self-supported electrode. Ni2Fe-ICP exhibits excellent electrocatalytic performance in the oxygen evolution reaction (OER). Specifically, Ni2Fe-ICP shows a low overpotential of 275 mV at a current density of 100 mA cm−2, outperforming commercial RuO2, and has superior stability at a high current density (150 mA cm−2 can be retained for at least 30 h). Furthermore, the real OER active species are revealed to be metal oxides that evolve during the OER process.

Emerging of the lattice oxygen mechanism (LOM) provides a new opportunity for enhancing oxygen evolution reaction (OER) activity. However, its stability suffers from metal cation dissolution and lattice oxygen anionic redox chemistry. In this paper, carbon dots (CDs)-modified nickel-iron MOF (Metal-Organic Framework) nanosheets (NiFe-BDC/CDs) were prepared for efficient OER electrocatalysis. The introduction of CDs promotes the hybridization of the O 2p band in the MOF with the metal 3d band near the Fermi level, leading to improved involvement of lattice oxygen in the oxygen evolution reaction. Additionally, C-M bonds formed between CDs and metal sites in MOF enhanced the stability of electrocatalyst. As results, the prepared NiFe-BDC/CDs electrodes demonstrated a current density of 100 mA cm-2 at overpotentials of 235 and 250 mV in alkaline freshwater and alkaline seawater, respectively, and a remarkable stability in alkaline seawater at 500 mA cm-2 for >100 h. This study provides a simple and versatile strategy for the design of OER electrocatalysts with highly active transition metal-based MOFs.

The integration of Fe dopant and interfacial FeOOH into Ni-MOFs [Fe-doped-(Ni-MOFs)/FeOOH] to construct Fe-O-Ni-O-Fe bonding is demonstrated and elucidate the origin of remarkable electrocatalytic performance of Ni-MOFs. X-ray absorption/photoelectron spectroscopy and theoretical calculation results indicate that Fe-O-Ni-O-Fe bonding can facilitate the distorted coordinated structure of Ni site with short nickel-oxygen bond and low coordination number, and can promote the redistribution of Ni/Fe charge density to efficiently regulate the adsorption behavior of key intermediates with near-optimal d-band center. Here the Fe-doped-(Ni-MOFs)/FeOOH with interfacial Fe-O-Ni-O-Fe bonding shows superior catalytic performance for OER with a low overpotential of 210 mV at 15 mA cm-2 and excellent stability with ~3% attenuation after 120 h cycle test. This study will provide a novel strategy to design high-performance Ni/Fe-based electrocatalysts for OER in alkaline media.

Over the past two decades, iron‐based metal–organic frameworks (Fe‐MOFs) have attracted significant research interest in biomedicine due to their low toxicity, tunable degradability, substantial drug loading capacity, versatile structures, and multimodal functionalities. Despite their great potential, the transition of Fe‐MOFs–based composites from laboratory research to clinical products remains challenging. This review evaluates the key properties that distinguish Fe‐MOFs from other MOFs and highlights recent advances in synthesis routes, surface engineering, and shaping technologies. In particular, it focuses on their applications in biosensing, antimicrobial, and anticancer therapies. In addition, the review emphasizes the need to develop scalable, environmentally friendly, and cost‐effective production methods for additional Fe‐MOFs to meet the specific requirements of various biomedical applications. Despite the ability of Fe‐MOFs–based composites to combine therapies, significant hurdles still remain, including the need for a deeper understanding of their therapeutic mechanisms and potential risks of resistance and overdose. Systematically addressing these challenges could significantly enhance the prospects of Fe‐MOFs in biomedicine and potentially facilitate their integration into mainstream clinical practice.

This study successfully fabricated Ni-Fe Prussian blue analogues (PBAs) on polytetrafluoroethylene (PTFE) membranes (Ni-Fe PBAs@M) through interfacial functionalization and in situ crystal growth. Structural and compositional analyses confirmed the formation of a hierarchical porous structure with uniformly distributed PBA nanocubes (55-80 nm), cyanide-bridged coordination, and a 2.1-fold increase in surface area. Under optimized synthesis conditions (Ni/Fe molar ratio 3:2, 60 °C, Ni(NO₃)₂ precursor), the membranes achieved over 99 % Cs⁺ removal from 0.05 ppm solutions within 60 min, with a considerable and promising adsorption capacity of 444.00 mg·m⁻² at 5.0 ppm Cs⁺. Performance remained stable across transmembrane pressures (0.1 MPa) and pH levels (5-10), with slightly enhanced kinetics under acidic conditions. The membrane exhibited strong selectivity, retaining over 92 % Cs⁺ removal efficiency even in the presence of high concentrations of competing ions (Na⁺, K⁺, Ca²⁺, Mg²⁺, 10²-fold excess), which is attributed to the favorable hydration radius of Cs⁺. Water-based regeneration maintained >97.5 % removal efficiency over three cycles. In real-world applications, the membrane achieved >90 % Cs⁺ removal from Pearl River water and ∼50 % removal from salt-lake brine, despite extreme ionic competition exceeding Cs⁺ concentrations by >10⁴-fold. Mechanistic investigations revealed that Cs⁺ immobilization involves surface proton exchange (derived from polarized water molecules), subsequent diffusion into the lattice structure, the formation of Fe/Ni-NC-Cs⁺ coordination bonds accompanied by a 0.6 % lattice contraction, and redox-mediated stabilization for enhanced retention. These findings demonstrate that Ni-Fe PBAs@M is a promising, scalable membrane for efficient Cs⁺ decontamination and resource recovery.

Iron-based metal-organic frameworks (Fe-MOFs) have been considered competitive catalyst candidates for the effective degradation of organic pollutants via advanced oxidation processes (AOPs) due to their unique porous architecture and tunable active site structure. However, little is known about the role of synergetic relationship between porous architecture and active site exposure of Fe-MOFs on catalysis for AOPs yet. Here, we demonstrated an overlooked compromise over these two features on modulating the catalytic ozonation reactivity of MIL-53(Fe) through a timescale-dependent crystal evolution. Enabled by intramolecular hydrogen bonds, the MIL-53(Fe) was subjected to six evolution steps in terms of crystal morphology, leading to a volcano plot of catalytic ozonation reactivity for Rhodamine B (RhB) degradation versus the crystallization time. Evidence suggested that the surface area of MIL-53(Fe) decreased dramatically, while the density of accessible active site increased when prolonging crystallization time, allowing for the facile modulation of catalytic ozonation reactivity of MIL-53(Fe). Electron paramagnetic resonance and fluorescence quantification tests verified that the screened MIL-53(Fe)s had a much better capacity for ∙OH generation than benchmark ozonation catalyst α-MnO2 and α-FeOOH. Moreover, the MIL-53(Fe) with the highest reactivity (i.e., MIL-53(Fe)-18H) could effectively destruct a broad spectrum of emerging and refractory organic pollutants and allow the thorough purification of secondary effluents discharged from textile dyeing & finishing industry for in situ reuse. Therefore, our study advances the understanding of the compromise effect between porous architecture and active site on catalysis reactivity of Fe-MOFs and promotes the rational design of more effective Fe-MOFs as well as their derivatives for environmental applications.

Iron-based metal–organic frameworks (Fe-MOFs) have emerged as promising candidates for drug delivery applications due to their low toxicity, structural flexibility, and safe biodegradation in a physiological environment. Here, we studied two types of Fe-MOFs: MIL-53 and MIL-88B, for in vitro drug loading and releasing of ibuprofen as a model drug. Both Fe-MOFs are based on the same iron clusters and organic ligands but form different crystal structures as a result of two different nucleation pathways. The MIL-53 structure demonstrates one-dimensional channels, while MIL-88B exhibits a three-dimensional cage structure. Our studies show that MIL-53 adsorbs more ibuprofen (37.0 wt %) compared to MIL-88B (19.5 wt %). A controlled drug release was observed in both materials with a slower elution pattern in the case of the ibuprofen-encapsulated MIL-88B. This indicates that a complex cage structure of MIL-88 is beneficial to control the rate of drug release. A linear correlation was found between cumulative drug release and the degree of material degradation, suggesting the biodegradation of Fe-MILs as the main drug elution mechanism. The cytotoxicity of MIL-88B was evaluated in vitro with NIH-3T3 Swiss mouse fibroblasts, and it shows that MIL-88B has no adverse effects on cell viability up to 0.1 mg/mL. This low toxicity was attributed to the morphology of MIL-88B nanocrystals. The very low toxicity and controlled drug release behavior of Fe-MIL-88B suggest that better materials for drug-delivery applications can be created by controlling not only the composition but also the crystal structure and nanoparticle morphology of the material.

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Developing highly efficient, low-cost, and durable oxygen evolution reaction (OER) electrocatalysts is extraordinarily desirable for achieving clean and sustainable hydrogen energy. Metal-organic frameworks (MOFs) are emerging as attractive candidates for OER electrocatalysts. Herein, a two-dimensional Fe-Ni MOF of Fe(py)2Ni(CN)4 (py = pyridine) is synthesized controllably to generate various nanostructures, including nanoboxes, nanocubes, nanoplates, and nanosheets. Since different morphologies expose different active crystal planes and generate disparate intrinsic active sites, these nanostructures exhibit obviously different electrocatalytic activities. Particularly, the nanoboxes with a hollow structure display superior electrocatalytic activity and stability for OER due to greater active surface area and higher intrinsic activity of the exposed crystal planes, delivering a low overpotential of 285 mV at 10 mA cm-2 and a small Tafel value of 50.9 mV dec-1 in a 1.0 M KOH solution. The morphology-dependent electrocatalytic properties demonstrated in this work provide an efficient strategy to optimize MOF precatalysts for electrochemical energy storage and conversion.

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The increasing global population and rapid depletion of energy resources have intensified the demand for renewable energy and advanced energy storage solutions. Supercapacitors, with their high power density, long cycle life, and fast charging capability, are emerging as a promising alternative to conventional batteries. This study reports, for the first time, the capacitive performance of a bimetallic FeNi metal‐organic framework (MOF) combined with multi‐walled carbon nanotubes (MWCNTs) on a carbon felt electrode. The composite was synthesized via a hydrothermal route and applied through a drop‐casting method. Electrochemical performance was evaluated using cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge–discharge techniques. The resulting electrode demonstrated a specific capacitance of about 180 F/g over a wide current density range, nearly 100% coulombic efficiency, a power density up to 3600 W/kg, and an energy density of about 91 Wh/kg. Moreover, it retained 90% of its capacity after 700 charge–discharge cycles, underscoring its stability. These findings highlight the FeNi MOF‐MWCNT composite as a promising candidate for high‐performance supercapacitor electrodes.

As a kind of well-known disease biomarker, uric acid (UA) is closely associated with normal metabolism and health. Despite versatile nanozymes facilitating the analysis of UA, most previous works could only generate single-signal outputs with unsatisfactory detection performance. Exploring a novel ratiometric fluorescent UA sensor with high sensitivity, reliability and portable sensing ability based on facile, low-cost nanozymes is still challenging. Herein, we report the first metal-organic-framework (MOF) nanozyme-originated ratiometric fluorescent UA sensor based on Fe3Ni-MOF-NH2 propelled UA/uricase/o-phenylenediamine tandem catalytic reaction. Different from previous reports, the peroxidase-like property and fluorescence of Fe3Ni-MOF-NH2 were simultaneously employed. In the absence of UA, only the MOF's fluorescence at 430 nm (FI430) can be observed, while the addition of UA will initiate UA/uricase catalytic reaction, and the generated H2O2 could oxidize o-phenylenediamine into highly fluorescent 2,3-diaminophenazine (DAP) (emission at 565 nm, FI565) under the catalysis of the MOF nanozyme. Coincidently, MOF's fluorescence can be quenched by DAP via the inner filter effect, resulting in a low FI430 value and high FI565 value, respectively. Therefore, H2O2 and UA can be alternatively detected through monitoring the above contrary fluorescence changes. The limit of detection for UA is 24 nM, which is much lower than those in most previous works, and the lowest among nanozyme-based ratiometric fluorescent UA sensors reported to date. Moreover, the portable sensing of UA via smartphone-based RGB analysis was facilely achieved by virtue of the above nanozyme-propelled tandem catalytic system, and MOF nanozyme-based molecular contrary logic pairs were further implemented accordingly.

By synthesizing a bimetallic iron and nickel organic framework (FeNi-MOF) hybrid as the nanozyme, herein we developed an innovative voltammetric ‘off–on’ aptasensor platform of interleukin-18 (IL-18) for the first-time. This nanozyme catalyzes the conversion of 1,2-diaminobenzene to diaminophenazinc (DAP), an electroactive substance. However, upon binding to the aptamer (Apt) sensing of IL-18, its enzyme-like activity is inhibited as the active sites are obscured by the Apt, leading to the disappearance of DAP current (signal ‘off’). Interestingly, in the presence of IL-18, the activity is restored because specific binding between the Apt and IL-18 displaces the Apt from the FeNi-MOF surface, resulting in an increase in DAP current (signal ‘on’). After optimizing key conditions, this ‘off-on’ nanozyme-based electrochemical aptasensor demonstrates excellent detection performance for IL-18 and provides a novel, simple, and reliable strategy for detecting various biomarkers by simply altering the relative Apt.

Metal-organic frameworks (MOFs) have emerged as promising precursors for the development of efficient non-noble metal electrocatalysts for oxygen evolution reaction (OER). Quasi-metal-organic frameworks, characterized by partially fractured connections between metal nodes and organic ligands, have attracted significant attention due to their large exposed active interfaces. To stimulate the development of quasi-MOF-based materials as OER catalysts, herein a Ni-Fe quasi-MOF catalyst was prepared through the pyrolysis of MIL-101(Fe) and subsequent ion exchange with Ni2+. The optimum catalyst MIL-101(Fe)350-Ni exhibits the lowest overpotential (290 mV) to achieve a current density of 10 mA cm-2, the smallest Tafel slope (89 mV dec-1) and the largest double-layer capacitance (0.268 mF cm-2). Furthermore, the current density drops only by ∼5 % (from 10 to 9.45 mA cm-2) after 20 h durability test. Experimental analysis suggests that the enhanced OER performance arises from the strong coupling effect between Fe and Ni, which improves the electron transfer efficiency and facilitates the active species generation. This work provide a feasible direction for constructing bimetallic quasi metal-organic frameworks to enhance the electrocatalytic OER performance and stability.

The design of bimetallic metal-organic frameworks (MOFs) with a hierarchical structure is important to improve the electrocatalytic performance of catalysts due to their synergistic effect on different metal ions. In this work, the catalyst comprises bimetallic iron-nickel MOF-derived FeNi phosphides, intricately integrated with phosphorus-doped reduced graphene oxide architectures (FeNi2P-C/P-rGA) through the hydrothermal and phosphating treatments. The hierarchical architecture of the catalyst is beneficial for exposing active sites and facilitating electron transfer. The FeNi2P-C/P-rGA catalyst exhibits excellent performance in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline electrolytes. Notably, FeNi2P-C/P-rGA requires only the overpotential of 93 and 210 mV to achieve a current density of 10 mA cm-2 for the HER and OER with small values of Tafel slope and charge transfer resistance, respectively. Furthermore, the catalyst exhibits boosted activity for overall water splitting with a low potential of 1.56 V. This work can be considered to extend the design of multilevel catalysts in the application of water splitting.

No abstract available

Nowadays, metal–organic framework (MOF) based oxides have been gradually regarded as promising gas-sensing materials. In this study, the small-sized NiFe2O4 polyhedrons were first synthesized through the pyrolysis of Fe/Ni-based bimetallic MOF precursors that were synthesized by ligand acid complexation. Subsequently, large-sized NFO polyhedrons with more stable morphology and structure were synthesized by changing the solvent composition. The concrete microstructure of the as-synthesized samples was characterized by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy and high-resolution transmission electron microscopy. The large-sized NFO polyhedron based sensors present satisfactory triethylamine (TEA) gas sensing performance, such as fast response speed (6 s to 50 ppm TEA), enhanced response values (18.9 to 50 ppm TEA), good selectivity and repeatability at a relatively low working temperature (190 °C). Only a few studies have reported on the use of MOF-derived NFO materials in TEA detection. Hence, our work expands the application of MOF-derived NFO materials. In addition, the sensing performance and sensing mechanism are discussed in detail.

Abstract It is impending but still a big challenge to design and synthesize electrocatalyst with typical nanostructure and efficient catalytic activity for hydrogen evolution reaction (HER). Herein, we report a low-temperature phosphorization process to synthesize nickel-iron bimetallic phosphides (NiFeP) using MIL-88-Fe2Ni MOF (metal-organic framework) as precursor. The as-synthesized NiFeP shows superior electrocatalytic performance with lower onset overpotential, smaller Tafel slope, bigger exchange current density and lower overpotential to reach the current density of 10 mA cm−2 than both NiP2 and FeP for HER in alkaline solution. The enhanced electrochemical activity may be attributed to the existence of the synergistic effect between NiP2 and FeP. SEM and TEM images show that the obtained NiFeP bimetallic phosphides preserve the size and morphology of the parent MIL-88-Fe2Ni MOF. And the prominent and stable performance of NiFeP nanorods for HER may also ascribes to the typical rod-like nanostructure with large specific surface area.

The coupling of lattice and heterostructure interfaces represents an effective strategy for disrupting the so-called scalar relationship and accelerating reactions involving multiple intermediates. In view of this, a lattice-heterostructure interfacial catalyst consisting of a crystalline Fe/Ni bimetallic MOF and amorphous Fe-MOF was designed in this paper for high-performance alkaline oxygen evolution reaction electrocatalysis. The strongly coupled lattice-heterostructure interface induces a unique synergistic effect that promotes electron transfer of the catalyst. The resulting catalyst exhibits exceptionally high catalytic activity for the oxygen evolution reaction in alkaline media, the Ni9Fe1-BDC-1@Fe-MOF coated on a glassy carbon electrode has an overpotential of 257 mV at a current density of 10 mA cm-2. Furthermore, this catalyst demonstrates a high electrochemical stability. These research results highlight the superiority of lattice-heterostructure interfaces in the development of advanced catalysts.

Alpha-glucosidase (α-Glu) plays a crucial role in regulating the normal physiological function of the body; therefore, α-Glu activity detection is crucial in clinical studies. In this study, a nickel-based metal-organic framework (Ni-MOF) co-doped with sulfur dots (SDs) and iron (Fe) was designed and constructed for the colorimetric detection of α-Glu. The SDs/Fe/Ni-MOF shows a very low Michaelis-Menten constant (0.0466 mM) for H2O2, suggesting a very high affinity for H2O2. Additionally, the free radicals generated by the nanozyme-catalyzed reaction were analyzed, and the feasibility of the nanozyme-catalyzed process was further verified using density functional theory. The bimetallic (Fe and Ni) can improve the catalytic activity of the material, and sulfur can improve the affinity with the substrate to further enhance the catalytic performance. Notably, hydroquinone (HQ) inhibits nanozyme activity, whereas α-Glu hydrolyzes alpha-arbutin (α-Arb) and subsequently produces HQ. Therefore, this study developed a method for detecting α-Glu activity using α-Arb as a substrate. This method has high selectivity, a wide detection range (1.00-100 U L-1), and a low detection limit (0.525 U L-1). Finally, the method was used to α-Glu activity detected in serum samples with good accuracy. This study provides a new method for the detection of α-Glu.

Development of high-efficiency and Earth-abundant bifunctional catalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is desirable to realize an efficient overall water splitting process. In this work, a highly active and durable bifunctional catalyst of coral-like nickel iron phosphide ultrathin nanosheets anchored on nitrogen-doped carbon nanoflake arrays on carbon cloth (CC-NC-NiFeP) was fabricated by using metal organic framework (MOF) derived nitrogen-doped carbon nanoflake arrays as catalyst supports. Combined with the electronic structure regulation by bimetallic phosphides and using three dimensional nitrogen-doped carbon nanoflakes as supports that provide a large specific surface area as well as fast charge/mass transport, the as-prepared CC-NC-NiFeP yields excellent bifunctional electrocatalytic activity in both the HER and OER in an alkaline medium with an overpotential of 94 mV and 145 mV to reach a current density of 10 mA cm-2, respectively. Meanwhile, the CC-NC-NiFeP can behave as both a cathode and anode simultaneously for overall water splitting, achieving a low cell voltage of 1.54 V to reach a current density of 10 mA cm-2, which outperforms that of most of the non-precious metal based catalysts.