MAPbBr3掺杂手性分子用于光催化

No abstract available

Due to their special physicochemical properties, organic-inorganic hybrid perovskite quantum dots (OIP QDs) are ideal and potential catalysts for the nitrogen reduction reaction (NRR). However, the OIP QD-based NRR is limited by poor water resistance, competitive suppression by the hydrogen evolution reaction, and inefficient active sites on the catalyst surfaces. Herein, to ensure an efficient NRR in aqueous solution, a water-resistant polycarbonate-part-encapsulated heterojunction of Zn,PtIV co-doped PbO-MAPbBr3 (PtIV/Zn/PbO/PC-Zn/MAPbBr3) is prepared through one-step electrospray-based microdroplet synthesis. Confirmed by both experimental and theoretical examinations, PbO is exposed on the PC-part-encapsulated surface to construct a Type I heterojunction. This heterojunction is further improved by synergistic co-doping with PtIV to facilitate efficient electron transfer for efficient photocatalysis of the NRR. Due to the active sites of the d-orbital electron-deficient Pt atoms (exhibiting a lower reaction energy barrier and highly selective N2 adsorption), the ammonia yield rate is 40 times higher than that without doping. This work initiates and develops on the application of OIP QDs in the NRR.

Organic-inorganic hybrid perovskite materials show great potential in photocatalysis and solar cells due to their excellent photoelectric properties, while interface defects affect their photocatalytic performance and stability. In this study, machine learning techniques were used to perform preliminary screening and prediction of high-performance passivation molecules (PMs), and density functional theory was used to investigate the effect of PMs on interfacial passivation performance. It was found that the presence of different chemical bonds between PMs and the interface can significantly change the interface properties. Therefore, the effect of PMs on the performance of interfacial photocatalytic CO2 reduction reaction was explored. When PMs present N-Pb bonds at the interface, CO2 is reduced to CH3OH, while S-Pb bonds selectively generate CH2O from CO2, making perovskite selectively generate O-containing carbonyl compounds. The autocatalytic performance of organic compounds at the perovskite interface is poor and is not easy to occur. This study combines perovskite interface passivation and photocatalytic performance, providing a new approach for selective catalysis at perovskite interfaces.

Semiconductor quantum dots (QDs) have emerged as a paradigm-shifting catalytic platform for visible-light-driven organic synthesis, owing to their highly tunable excitonic properties. However, the critical role of nanoconfined exciton evolution in governing surface reactions remains experimentally elusive. Here, we synthesized Au@perovskite QD superstructures for in-situ surface-enhanced Raman spectroscopy to probe exciton-molecular crosstalk during the photocatalytic self-coupling of aromatic thiols on QD surfaces. We find that quasi-ligand coordination of thiols with surface Pb sites simultaneously attenuates three exciton relaxation pathways: radiative recombination, Auger recombination, and exciton-phonon coupling, while enhancing trap-assistant recombination. Thermodynamically, coordinating molecules with varying substituent groups reduce the exciton binding energy (Eb) in QD systems through their tunable dipole moments. This excitonic modulation effectively lowers the activation barrier during the reaction and thus facilitates S-S bond coupling, as demonstrated by substituting -Cl with -OCH3, which reduces Eb by 38.3% and increases the reaction rate by 84.7%. Our work reveals exciton-molecular crosstalk as a key mechanistic aspect in QD catalysis and enriches the theoretical framework of heterogeneous catalytic processes under quantum confinement.

A relatively new addition to the application portfolio of lead halide perovskites is to photosensitize molecular triplets for a variety of photochemical applications. Here we report visible-light-driven isomerization and cycloaddition of organic molecules sensitized by spectrally-tunable perovskite nanocrystals. We first demonstrate with stilbene as the substrate molecule that photoisomerization can proceed efficiently and rapidly by either directly grafting carboxylated stilbene onto nanocrystal surfaces or using triplet-acceptor ligands as the energy relay. The relay approach is more generally applicable as it does not require anchoring-group functionalization of substrate molecules, allowing us to facilely extend it to isomerization of a series of substituted stilbene molecules and ring-closing isomerization of diarylethene, as well as intermolecular [2+2] cycloaddition of acenaphthylene. This study opens an avenue of energy-transfer photocatalysis using perovskite nanocrystals.

Two-dimensional organic–inorganic hybrid perovskites (OIHPs) have excellent photoelectric properties, such as high charge mobility and a high optical absorption coefficient, which have attracted enormous attention in the field of optoelectronic devices and photochemistry. However, the stability of 2D OIHPs in solution is deficient. In particular, the lack of stability in polar solutions hinders their application in photochemistry. In this work, (iso-BA)2PbI4 was used as a model to explore the three possibilities of the stable existence of a 2D perovskite in aqueous solution. And two of these systems that stabilize the presence of (iso-BA)2PbI4 were further investigated through electrochemical testing. Moreover, (iso-BA)2PbI4 2D hybrid perovskites exhibited an outstanding degradation rate. The chiral perovskite (R/S-MBA)2PbI4 is able to degrade a 30 mg/L methyl orange solution completely within 5 min, making it one of the fastest catalysts for this particular organic reaction. Further, based on the electron spin resonance test, a degradation mechanism by the halide perovskite was proposed. Based on the great catalytic performance as well as good reusability and stability, (R/S-MBA)2PbI4 perovskites are expected to be a new generation of catalysts, making a great impact on the application of asymmetrically catalyzed photoreactions.

Chiral ligand modification has emerged as a promising route to confer intrinsic chirality in perovskite nanocrystals (NCs), thereby imparting them with optically active properties and rendering great superiority in the next generation of circularly polarized luminescence. However, the functionalization of chiral ligand is not fully explored and the underlying mechanism governing chirality transfer remains elusive. Herein, tryptophan (Try), a naturally occurring chiral amino acid, is verified to serve as multidentate chiral ligands attaching on the surface of perovskite NCs. Such strong coordination favors the chirality imprinting on the electronic state of CsPbBr3, resulting in notable circular dichroism features and circularly polarized luminescence with a maximum glum of 2.3 × 10−3. It is intriguing that the intermolecular interaction between Try ligands anchored on two neighboring NCs contribute to chiral optical properties as well. The RDG‐NCI analysis have confirmed the hydrogen bond between the amine and carboxylic groups on chiral Try, which may drive the chiral assembly of perovskite NCs.

This study presents a post-synthetic ligand modification strategy for the generation of chiroptically active, blue emitting CsPbBr3 nanoparticles (NPs) - an expansion to the library of 3D chiral perovskite nanomaterials. Addition of [R- and S-] 1-phenylethylamine, 1-(1-naphthyl)ethylamine, or 2-aminooctane to the synthesized CsPbBr3 NPs is shown to induce Cotton effects in the NP first exciton transition, suggestive of a successful electronic coupling between the chiral ligands and the NPs. The availability of these chiral CsPbBr3 NPs thrusts them into the forefront of perovskite nanomaterials for examining the implications of the chiral induced spin selectivity (CISS) effect and other applications in spintronics.

Hybrid organic-inorganic perovskites have shown promise in circularly polarized light source applications when chirality has been introduced. Circularly polarized photoluminescence (CPL) is a significant tool for investigating the chiroptical properties of perovskites. However, further research is still urgently needed, especially with regard to optimization. Here we demonstrate that chiral ligands can influence the electronic structure of perovskites, increasing the asymmetry and emitting circularly polarized photons in photoluminescence. After the modification of chiral amines, the defects of films are passivated, leading to enhanced radiation recombination for which more circularly polarized photons are emitted. Meanwhile, the modification increases the asymmetry in the electronic structure of perovskites, manifested by an increase in the magnetic dipole moment from 0.166 to 0.257 μB and an enhanced CPL signal. This approach offers the possibility of fabricating and refining circularly polarized light-emitting diodes.

In this study, MAPbBr3 was encapsulated within a porous metal-organic framework (CAU-17) via ligand-assisted reprecipitation, which enhanced the perovskite's photocatalytic stability. This encapsulation approach not only stabilises the photocatalytic performance of MAPbBr3 but also enables further enhancement of its catalytic efficiency through halogen anion group modification. Results from various characterisation demonstrate that the CAU-17/MAPbBr2Cl composites possess excellent properties, achieving a tetracycline degradation efficiency of up to 92%.

Photocatalytic hydrogen evolution (PHE) is attractive for sustainable energy production, yet its efficiency lags photovoltaic conversion mainly due to the step of H‒H bonding for hydrogen generation on photocatalysts. Herein, the spin-enhanced PHE using photocatalysts of chiral perovskites (MBPI) are reported, where the spin orientations of photocarriers are aligned antiparallelly for H‒H bonding via the chiral-induced spin selectivity (CISS) effect. It is observed that the rac-MBPI shows a 3.5-fold enhancement in PHE activity compared with R/S-MBPI under visible light illumination, which is related to the chiral distortions of octahedral units in perovskite structures. Structural distortions lead to the spin polarization of photogenerated carriers in chiral perovskites due to the CISS effect, as revealed by magneto-photocurrent measurements. Compared with the parallel spins in R/S-MBPI, the antiparallel spins in rac-MBPI are more favorable for the coupling of H* radicals, as proven by the electron paramagnetic resonance experiments. The spin-enhanced mechanism for PHE is universal for reduced dimensional (quasi-2D) chiral perovskites, and the H2 yield rate is optimized up to 0.61 mmol g-1 h-1 with an excellent stability over 100 hours.

Owing to their attractive optical and chiroptical properties, chiral metal halide perovskites have received increasing attention, with potential applications ranging from photonics and optoelectronics to spintronics. Metal halide perovskite nanocrystals with either intrinsic or extrinsic (e.g., chiral ligand‐induced) chirality have been reported recently, and the interplay between these two types of chirality has yet to be addressed. Herein, the inversion and tuning of excitonic optical activity is reported in intrinsically chiral perovskite nanoplatelets, originating from interactions between their structural chirality (due to the spontaneously formed screw dislocations in the crystalline lattice) and the surface enantiomeric (R/S) chiral ligands R/S‐phenylethylammonium bromide. Through post‐preparative exposure of the perovskite nanoplatelets to these R/S ligands of varied contents, either chiral ligand‐induced intrinsic chirality inversion or negative and positive Cotton effects induced by the ligands via electronic coupling between the ligand and the nanoplatelets are identified. These findings deepen understanding of the modulation of excitonic optical activity in chiral perovskites and can guide the rational design and synthesis of novel chiral materials.

Manipulating spin polarizations of photoexcited electrons has been found to play a vital role in enhancing photocatalytic CO2 conversion by suppressing carrier recombination. In this work, photocatalytic CO2 reduction conversion efficiencies are significantly enhanced by chirality-regulated spin-polarization of CsPbBr3 perovskite nanocrystals. We propose the chirality-regulated perovskite thin films by incorporating chiral molecules (MBA:Br) into all-inorganic CsPbBr3 perovskite nanoplates (NPLs), resulting in (R)- and (S)-2D Ruddlesden–Popper perovskite (RPP)/NPL hybrids. In this configuration, the chiral 2D RPP perovskites offer a significant chiroptical response that promotes the generation of spin-polarized electrons. The chirality-regulated spin-polarization of 2D RPP/NPLs hybrid perovskite thin films has significantly suppressed charge carrier recombination rates, thereby enhancing the efficiency of photocatalytic CO2 reduction. By harnessing the synergistic effects of induced chirality and the application of an external magnetic field of 0.3 T, the photocatalytic CO2 reduction efficiencies of the chiral perovskites can be enhanced to be five times that of the pristine CsPbBr3 perovskite NPLs. The interplay between structure, chirality, spin polarization, and carrier dynamics associated with the enhanced photocatalytic activity of perovskite nanocrystals was systematically analyzed using grazing-incidence wide-angle X-ray scattering (GIWAXS) spectroscopy, magnetic circular dichroism (MCD) spectroscopy, and time-resolved photoluminescence (PL) techniques. Our results pave the way for the manipulation of spin-polarized electrons through chirality-regulated perovskite nanocrystals, significantly enhancing photocatalytic CO2 reduction efficiencies and highlighting their strong potential for future solar-to-fuel conversion applications.

We have synthesized inherently chiral cesium lead halide perovskite magic-sized clusters (PMSCs) and ligand-assisted metal halide molecular clusters (MHMCs) using the achiral ligands octanoic acid (OCA) and octylamine (OCAm). UV-vis electronic absorption was used to confirm characteristic absorption bands while circular dichroism (CD) spectroscopy was utilized to determine their chiroptical activity in the 412-419 and 395-405 nm regions, respectively. In contrast, the larger sized counterpart of PMSCs, namely, perovskite quantum dots (PQDs), do not show chirality. The inherent chirality of the clusters is tentatively attributed to a twisted chiral layered structure, defect-induced chiral structure, or twisted Pb-Br octahedra.

Magnetic impurity doping in semiconductors has emerged as an important strategy to endow exotic photophysical and magnetic properties. While most reported hosts are centrosymmetric semiconductors, doping magnetic ions into a noncentrosymmetric chiral semiconductor can offer additional control of photonic and spin polarization. In this work, we synthesized a Mn2+-doped chiral two-dimensional (2D) perovskite, Mn2+:(R-MPA)2PbBr4 (R-MPA+ = R-methyl phenethylammonium). We found that the optical activity of chiral 2D perovskites is enhanced with an increased concentration of Mn2+ ions. Additionally, efficient energy transfer from the chiral host to the Mn2+ dopants is observed. This energy transfer process gives rise to circularly polarized luminescence from the excited state of Mn2+ (4T1 → 6A1), exhibiting a photoluminescence quantum yield up to 24% and a dissymmetry factor of 11%. The exciton fine structures of undoped and Mn2+-doped (R-MPA)2PbBr4 are further studied through magnetic circular dichroism (MCD) spectroscopy. Our analysis shows that chiral organic cations lead to an exciton fine structure splitting energy as large as 5.0 meV, and the splitting is further increased upon Mn2+ doping. Our results reveal the strong impacts of molecular chirality and magnetic dopants on the exciton structures of halide perovskites.

No abstract available

Poor stability is a significant challenge to organic–inorganic hybrid perovskites for practical optoelectronic applications, which results from their inherent ionic nature and soft structures. The coordination bonding strategy is supposed to be a valid approach by enhancing the interaction between the cations and inorganic frameworks. Herein, the first pair of cation‐coordinated perovskites with high stability, achieved through coordination bonds between the cations and [PbXn] anions instead of the weak hydrogen bonds and van der Waals force presented in conventional ionic perovskites, is reported. In L/R‐(4HOPD)PbBr3 (4HOPD = 4‐hydroxypiperidine cation) (L/R=Left/Right–handed), one of the six halogen atoms is replaced by an oxygen atom from the cation. The PbO bond contributes to the high stability under a double 85 test. L/R‐(4HOPD)PbBr3 crystallizes in the tetragonal system, belonging to one of 11 enantiomorphic space group types, P41212 and P43212. Similar to quartz, the chirality originates from the helical assembly of achiral units. The chirality‐induced optical rotatory power is 16.84° mm−1 at 404 nm. Moreover, the uniaxial negative birefringent property with a comparable Δn value makes it a good alternative to quartz. The remarkable stability of this new perovskite presents significant potential for further investigation into stable perovskites and their applications in optical rotation and polarizing optics.

The performance of perovskite nanocrystals (NCs) in optoelectronics and photocatalysis is severely limited by the presence of large amounts of crystal boundaries in NCs film that greatly restricts energy transfer. Creating heterostructures based on perovskite NCs and 2D materials is a common approach to improve the energy transport at the perovskite/2D materials interface. Herein, methylamine lead bromide (MAPbBr3 , MA: CH3 NH3 + ) perovskite NCs are homogeneously deposited on highly conductive few-layer MXene (Ti3 C2 Tx ) nanosheets to form heterostructures through an in situ solution growth method. An optimal mixed solvent ratio is essential to realize the growth of perovskite NCs on Ti3 C2 Tx nanosheets. Time-resolved photoluminescence spectroscopy, transient absorption spectroscopy, and the photoresponse of electron- and hole-only photoelectric conversion devices reveal the interfacial energy transfer behavior within MAPbBr3 /Ti3 C2 Tx heterostructures. The present investigation may provide a useful guide toward use of halide perovskite/2D material heterostructures in applications such as photocatalysis as well as optoelectronics.

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We demonstrate appropriate tuning of heterojunctions in CsPbBrxCl3−x−MoS2 composites (where x=0,1,2,3) by controlled regulation of the halide stoichiometry in the perovskite. A thorough optimization procedure determined the most effective photocatalyst, considering the pristine MoS2, perovskites with varying halide ratios, various physical mixing ratios of the two, and in‐situ synthesized composite ratios of CsPbBrxCl3−x and MoS2 (2 : 1, 1.5 : 1, 1 : 1, 1 : 1.5, 1 : 2). Under two hours of exposure to visible light, a remarkable photocatalytic performance of CsPbBrCl2 : MoS2 with a 1 : 2 ratio was observed, removing 98 % of the methylene blue (MB) dye. Notably, only the CsPbBrCl2 and MoS2 composite demonstrated higher efficiencies since it resulted in a n‐n type II heterojunction. Additionally, the CsPbBrCl2 : MoS2 composite exhibits the highest reaction rate constant, fifteen times higher than the pristine perovskite. Reusability assessment of this combination revealed sustained activity of 87 % for up to 5 cycles. The hydrogen evolution reaction investigations were carried out using the optimized CsPbBrCl2 : MoS2 composite, which yielded 265 times more hydrogen than pristine CsPbBrCl2. The Faradaic efficiency for 1 : 2 CsPbBrCl2 : MoS2 was found to be 96.61 %. Our results offer crucial perspectives on optimizing perovskite‐MoS2 composites and demonstrate their utility in sustainable applications, including water treatment, renewable energy harvesting, and environmental remediation.

Lead halide perovskites and related main-group halogenido metalates offer unique semiconductor properties and diverse applications in photovoltaics, solid-state lighting, and photocatalysis. Recent advances in incorporating chiral organic cations have led to the emergence of chiral metal-halide semiconductors with intriguing properties, such as chiroptical activity and chirality-induced spin selectivity, enabling the generation and detection of circularly polarized light and spin-polarized electrons for applications in spintronics and quantum information. However, understanding the structural origin of chiroptical activity remains challenging due to macroscopic factors and experimental limitations. In this work, we present an achiral perovskite derivative [Cu2(pyz)3(MeCN)2][Bi3I11] (CuBiI; pyz = pyrazine; MeCN = acetonitrile), which exhibits remarkable circular dichroism (CD) attributed to the material's noncentrosymmetric nature. CuBiI features a unique structure as a poly-threaded iodido bismuthate, with [Bi3I11]2- chains threaded through a cationic two-dimensional coordination polymer. The material possesses a low, direct optical band gap of 1.70 eV. Notably, single crystals display both linear and circular optical activity with a large anisotropy factor of up to 0.16. Surprisingly, despite the absence of chiral building blocks, CuBiI exhibits a significant degree of circularly polarized photoluminescence, reaching 4.9%. This value is comparable to the results achieved by incorporating chiral organic molecules into perovskites, typically ranging from 3-10% at zero magnetic field. Our findings provide insights into the macroscopic origin of CD and offer design guidelines for the development of materials with high chiroptical activity.

The ability to design halide perovskite nanocrystals (PNCs) with circularly polarized luminescence (CPL) offers exceptional potential in photonic technologies. Despite recent inspiring advances, the creation of PNCs with full-color tailorablity, outstanding CPL, and long-term stability remains a substantial challenge. Herein, a robust strategy to craft CPL-active PNCs is reported, exhibiting appealing full-color tunable wavelengths, enhanced CPL, and prolonged stability. In contrast to conventional methodologies, this strategy utilizes chiral nematic mesoporous silica (CNMS) as host to render in situ confined growth of diverse achiral PNCs. By strategically engineering photonic bandgap, adjusting loading amount of PNCs, and manipulating cations/anion compositions of PNCs, robust CPL responses with tunable wavelength and intensity are successfully obtained. The resulting PNCs-CNMS achieves stable CPL emissions with full-color tunability and impressive luminescent dissymmetric factors up to -0.17. Remarkably, silica-based hosts as a protective barrier confer exceptional resistance to humidity, photodegradation, and thermal stability, even up to 95 °C. Furthermore, the ability to achieve reversible CPL switching within PNCs-CNMS is attainable by leveraging the responsiveness of CNMS matrix or dynamic behavior of impregnated PNCs. Additionally, circularly polarized light-emitting diode devices based on PNCs-CNMS can be conveniently fabricated. This research affords a powerful platform for designing functional chiroptical materials.

The effect of chemical-composition modification on the chiroptical property of chiral organic ammonium cation-containing organic inorganic hybrid perovskite (chiral OIHP) is investigated. Varying the mixing ratio of bromide and iodide anions in (S- or R-C6H5CH2(CH3)NH3)2PbI4(1-x)Br4x modifies the bandgap of chiral OIHP, leading to a shift of the circular dichroism (CD) signal from 495 to 474 nm. However, it is also found that an abrupt crystalline structure transition occurs, and the CD signal is turned off when iodide-determinant phases are transformed into the bromide-determinant phase. To obtain CD in the wavelength range where the bromide-determinant phase is supposed to exhibit chiroptical activity, that is, <474 nm, S- or R-C12H7CH2(CH3)NH3 with a larger spacer group can be adopted; thus, the CD signal can be further blue-shifted to ~375 nm. Here we show that chemical-composition modification of chiral OIHP affects the chiroptical properties of chiral OIHP in two ways: 1) tuning the wavelength of CD by modulating the excitonic band structure and 2) switching the CD on and off by inducing a crystalline-structure change. These properties can be utilized for structural engineering of high-performance chiroptical materials for spin-polarized light-emitting devices and polarization-based optoelectronics.

The search for high-performance double perovskite-related materials remains constrained by the limited synthetic accessibility of bimetallic halides compared to their conventional halide double perovskite counterparts, leaving substantial unexplored territory in this domain. A promising structural modification strategy involves the incorporation of chiral organic moieties into the metal halide frameworks, enabling precise engineering of noncentrosymmetric structures toward targeted functional properties. Here, we report a pair of chiral two-dimensional (2D) Cu(I)-Pb bimetallic bromides (R/S-PCA)4Cu2PbBr8·H2O (R/S-CuPbBr, R/S-PCA = R/S-3-piperidinecarboxylic acid) and investigate their behavior under external stimuli including pressure and temperature. The R/S-CuPbBr compounds crystallize in a noncentrosymmetric monoclinic C2 space group, consisting of inorganic bimetal [Cu2PbBr8] layers and organic layers formed via hydrogen bonding interactions. For comparison, another pair of 2D Pb-based bromides (R/S-PCA)3Pb2Br7·H2O (R/S-PbBr) was synthesized, crystallizing in the noncentrosymmetric orthorhombic P212121. These materials exhibit broadband yellow emission and circularly polarized luminescence emission at room temperature. The glum values of R/S-CuPbBr and R/S-PbBr are 8.63 × 10-3 and -7.99 × 10-3, 4.33 × 10-3 and -3.52 × 10-3, respectively. Density functional theory (DFT) calculations reveal R/S-CuPbBr and R/S-PbBr are indirect and direct bandgap semiconductors, respectively. More importantly, R-CuPbBr exhibits dramatic enhancements in optical properties under high pressure, with an 8-fold increase in photoluminescence and 44-fold boost in second-harmonic generation at elevated pressure.

The photoelectric properties of perovskite quantum dots make them have great potential in photocatalytic antibacterial applications. However, commonly used long-chain ligands are not conducive to the transfer of photogenerated charge carriers in perovskite quantum dots. In this work, we used short chain ligands with higher conjugated systems (BODIPY-OH) for surface regulated synthesis of MAPbBr3 quantum dots (BDP/QDs). We found that there is a photogenerated carrier transfer process between BODIPY-OH and MAPbBr3 quantum dots. BODIPY-OH can effectively separate the photogenerated carriers in MAPbBr3 quantum dots. Due to this property, BDP/QDs have great application prospects in the field of photocatalysis. Using the specific chemical trapping techniques, we show that the binding of BODIPY-OH successfully enhances the singlet oxygen generation ability of MAPbBr3 quantum dots through the process of photogenerated carrier transfer. Based on the excellent waterproof performance of SiO2, we further improved the water stability of BDP/QDs using SiO2 (SiO2@BDP/QDs). The photogenerated singlet oxygen generated by SiO2@BDP/QDs has an effective antibacterial effect on Escherichia coli. This work provides new ideas and understanding for designing halide perovskite photocatalytic antibacterial materials for efficient antibacterial effects.

Considering the wide band gap of La2Ti2O7, and the limited separation efficiency of charge carriers in MAPbBr3, we designed and easily fabricated the MAPbBr3/La2Ti2O7 dual perovskite heterojunction with similar crystal...