MAPbBr3作为光催化剂

The proper and adjustable band structure and positive visible-light response enable halide perovskite (MAPbBr3) as a promising photocatalyst for CO2 reduction. Considering the extremely poor water resistance and severe carrier...

To address the poor stability of lead halide perovskite (LHP) nanoparticles (NPs), monodisperse methylammonium lead bromide (MAPbBr3, M-PE) NPs were successfully encapsulated with a thin layer (10 nm) of poly(norepinephrine) (PNE) by in-situ polymerization. The PNE layer endowed M-PE NPs with high structural stability against severe environment. Furthermore, the chemical interaction between M-PE and PNE facilitates to construct the core@shell composite, as well as contributes to the enhanced light-harvesting capacity, and improved photoelectronic conversion efficiency in photocatalytic activity. The encapsulated NPs M-PE@PNE with the bandgap of 2.04 eV degraded the organic pollutant of malachite green by 81 % in less than 2 h under visible light, which was 4.5 times higher than pristine M-PE NPs. This work provides a practical approach to stabilize and boost MAPbX3 photocatalyst and carries enormous potential in wide engineering applications.

Organic-inorganic hybrid halide perovskites have emerged as promising photocatalysts for hydrogen production because of their high absorption coefficients and large carrier diffusion lengths. However, the synthesis and development of organic-inorganic perovskite bromide photocatalysts have not been fully explored. Herein, we report on a novel high-activity Bismuth (Bi) doped CH3NH3PbBr3 (MAPbBr3) photocatalyst that was successfully synthesized using the reverse-temperature crystallization method. This material exhibited a reduced band gap and increased free-carrier concentration compared to pure MAPbBr3. Molecular dynamics and lattice changes within the photocatalyst were systematically investigated using solid-state nuclear magnetic resonance spectroscopy (NMR). The photocatalyst employs hypophosphorous acid (H3PO2) as a stabilizer and platinum (Pt) as a co-catalyst in the photocatalytic hydrogen bromide (HBr) splitting system, achieving a hydrogen evolution rate of 3946.52 μmol·g-1·h-1 under visible light irradiation. Our experimental results suggest that the enhanced photocatalytic performance is attributed to Bi doping, which modifies the charge distribution in the region of the lead (Pb) octahedron, thereby promoting effective charge separation and improving the hydrogen production efficiency. This study provides new insights into the photocatalytic hydrogen production capabilities of organic-inorganic hybrid bromide perovskites.

While the metal halide perovskite materials are emerging as potentially promising photocatalysts, they still suffer from the intrinsic instability, seriously hampering their further practical applications. In this study, a perovskite-based composite with a sandwich structure is first established to realize the encapsulation of individual octylamine-capped MAPbBr3 (OM-PE) quantum dots (QDs), and the Zeolitic Imidazolate Framework-67 (ZIF-67) isolates the individual OM-PE@PbBrOH QDs (2 nm) to preserve their unique optoelectronic properties while preventing degradation from environmental factors. The resulting sandwich composite was proved to be a staggered-gap heterostructure with a p-n junction, in which the PbBrOH layer acted as a water-resisting covering and ZIF-67 layer promoted the electron mobility. Benefiting from the chemical interactions and interfacial charge dynamics among the different layers, the OM-PE@PbBrOH⊂ZIF-67 composite exhibited the superior stability in water for two months, and presented an enhanced photodegradation efficiency of organic dyes (malachite green, methylene blue and rhodamine B), which is around 24 times higher than that of pristine perovskite. By integrating the respective merits of each component, this work unprecedentedly constructs the 2 nm sandwich-like OM-PE@PbBrOH⊂ZIF-67 composite, and opens new avenues for stable, efficient, and multifunctional photocatalytic systems, with potential applications beyond wastewater treatment.

No abstract available

Efficient artificial photosynthesis of disulfide bonds holds promises to facilitate reverse decoding of genetic codes and deciphering the secrets of protein multilevel folding, as well as the development of life science and advanced functional materials. However, the incumbent synthesis strategies encounter separation challenges arising from leaving groups in the ─S─S─ coupling reaction. In this study, according to the reaction mechanism of free-radical-triggered ─S─S─ coupling, light-driven heterojunction functional photocatalysts are tailored and constructed, enabling them to efficiently generate free radicals and trigger the coupling reaction. Specifically, perovskites and covalent organic frameworks (COFs) are screened out as target materials due to their superior light-harvesting and photoelectronic properties, as well as flexible and tunable band structure. The in situ assembled Z-scheme heterojunction MAPB-M-COF (MAPbBr3 = MAPB, MA+ = CH3 NH2 + ) demonstrates a perfect trade-off between quantum efficiency and redox chemical potential via band engineering management. The MAPB-M-COF achieves a 100% ─S─S─ coupling yield with a record photoquantum efficiency of 11.50% and outstanding cycling stability, rivaling all the incumbent similar reaction systems. It highlights the effectiveness and superiority of application-oriented band engineering management in designing efficient multifunctional photocatalysts. This study demonstrates a concept-to-proof research methodology for the development of various integrated heterojunction semiconductors for light-driven chemical reaction and energy conversion.

No abstract available

Although organic-inorganic lead halide perovskite nanocrystals (NCs) have emerged as new semiconductor photocatalysts with excellent photocatalytic performance, their stability remains inferior to that of all-inorganic lead halide perovskite NCs. To address this limitation, we propose a one-step in situ polymerization strategy via a CH3NH3PbBr3 NCs-initiated photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer polymerization to construct CH3NH3PbBr3-PBA/PMA gel composites, demonstrating the feasibility of both oxygenated and oxygen-free preparation processes. In this system, CH3NH3PbBr3 NCs serve dual roles: catalyzing the polymerization reaction and endowing the nanocomposites with fluorescence properties. By adjusting the cross-linker content, gel composites with tunable mechanical strength were successfully fabricated. Furthermore, the composites exhibited sustained fluorescence intensity for over 15 days in air and water and enhanced ethanol resistance, with the polymer matrix significantly improving the environmental stability of CH3NH3PbBr3 NCs.

Development of graphene/perovskite heterostructures mediated by polymeric materials may constitute a robust strategy to resolve the environmental instability of metal halide perovskites and provide barrierless charge transport. Herein, a straightforward approach for the growth of perovskite nano-crystals and their electronic communication with graphene is presented. Methylammonium lead bromide (CH3NH3PbBr3) nano-crystals were grown in a poly[styrene-co-(2-(dimethylamino)ethyl methacrylate)], P[St-co-DMAEMA], bi-functional random co-polymer matrix and non-covalently immobilized on graphene. P[St-co-DMAEMA] was selected as a bi-modal polymer capable to stabilize the perovskite nano-crystals via electrostatic interactions between the tri-alkylamine amine sites of the co-polymer and the A-site vacancies of the perovskite and simultaneously enable Van der Waals attractive interactions between the aromatic arene sites of the co-polymer and the surface of graphene. The newly synthesized CH3NH3PbBr3/co-polymer and graphene/CH3NH3PbBr3/co-polymer ensembles were formed by physical mixing of the components in organic media at room temperature. Complementary characterization by dynamic light scattering, microscopy, and energy-dispersive X-ray spectroscopy revealed the formation of uniform spherical perovskite nano-crystals immobilized on the graphene nano-sheets. Complementary photophysical characterization by UV-Vis absorption, steady-state, and time-resolved fluorescence spectroscopy unveiled the photophysical properties of the CH3NH3PbBr3/co-polymer colloid perovskite solution and verified the electronic communication within the graphene/CH3NH3PbBr3/co-polymer ensembles at the ground and excited states.

It is an important but difficult issue to identify charge and energy transfer processes in materials where multiple band gaps coexist. Conventional methods using transient absorption and optoelectrical characterization based on devices could not provide a clear picture of transfer dynamics. According to the bimolecular and monomolecular nature of each process, the carrier dynamics is supposed to solve this issue. In this work, we established a novel, convenient and universal strategy based on the calculation of carrier dynamics to distinguish energy/charge transfer and reveal their transfer dynamics in methylammonium lead bromide (MAPbBr3) films with mixing wide-band gap small grains and narrow-band gap large grains. A highly efficient charge transfer process is confirmed with a high negative nonradiative bimolecular recombination coefficient of −2.12 × 10–7 cm–3 s–1, indicating that free carriers within small grains are efficiently transferred from small grains to large grains. As a result, emission from large grains becomes dominant when increasing the photoexcitation intensity. In addition, current-density-dependent electroluminescence results in emission only from large grains, further verifying the charge transfer process. Moreover, it is interesting to find that when decreasing the size of small grains, the charge transfer process is facilitated, leading to an increased nonradiative bimolecular recombination coefficient from −2.12 × 10–7 to −4.01 × 10–7 cm–3 s–1 in large grains. Our work provides a convenient strategy to identify and quantify energy and charge transfer in metal halide perovskites, which can be used to enrich our understanding of perovskite photophysics.

Halide perovskite single-crystals have recently been widely highlighted to possess high light harvesting capability and superior charge transport behaviour, which further enable their attractive performance in photovoltaics. However, their application in photoelectrochemical cells has not yet been reported. Here, a methylammonium lead bromide MAPbBr3 single-crystal thin film is reported as a photoanode with potential application in photoelectrochemical organic synthesis, 2,5-dimethoxy-2,5-dihydrofuran. Depositing an ultrathin Al2O3 layer is found to effectively passivate perovskite surface defects. Thus, the nearly 5-fold increase in photoelectrochemical performance with the saturated current being increased from 1.2 to 5.5 mA cm−2 is mainly attributed to suppressed trap-assisted recombination for MAPbBr3 single-crystal thin film/Al2O3. In addition, Ti3+-species-rich titanium deposition has been introduced not only as a protective film but also as a catalytic layer to further advance performance and stability. As an encouraging result, the photoelectrochemical performance and stability of MAPbBr3 single-crystal thin film/Al2O3/Ti-based photoanode have been significantly improved for 6 h continuous dimethoxydihydrofuran evolution test with a high Faraday efficiency of 93%. Perovskite single-crystal thin films inherit the advantages of low trap-states, well-defined thickness and remarkable stability. Now, researchers successfully employed MAPbBr3 single-crystal thin film as photoanode in the photoelectrochemical production of organic 2,5-dimethoxy-2,5-dihydrofuran.

No abstract available

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...

Halide perovskite has shown great potential in photocatalysis owing to its diversity, suitable energy band alignment, rapid charge transfer, and excellent optical properties. However, poor stability, especially under humid conditions, hinders their practical application in photocatalysis. In this work, we report the encapsulation of inorganic–organic hybrid perovskite QDs into MIL-101(Cr) through an in situ growth strategy to prepare a series of MAPbBr3@MIL-101(Cr) (MA = CH3NH3+) composites. The perovskite precursors, i.e., MABr and PbBr2, were successively introduced into the pores of MOF, where the perovskite quantum dots were self-assembled in the confined environment. In photocatalytic CO2 reduction, 11%MAPbBr3@MIL-101(Cr) composite displayed the best performance among the composites with a total CO and CH4 yield of 875 μmol g−1 in 9 h, which was 8 times higher than that of the pure MAPbBr3. Such high gas production efficiency could be maintained for 78 h at least without structural and morphologic decomposition. The remarkable stability and catalytic activity of composites are mainly due to the synergistic effect and improved electron transfer between MAPbBr3 and MIL-101(Cr). Moreover, these composites revealed a novel mechanism, showing switched CH4 selectivity with the controlling of the perovskite location and contents. Those with perovskites encapsulated in the mesopores of MIL-101(Cr) were more preferential for CO production, while those with perovskites encapsulated in both meso- and micropores could produce CH4 dominantly.

Based on the large visible light absorption coefficient and tunable band gap of MAPbBr3, weakening the strong photo-generated carrier recombination tendency to exploit the CO2 reduction potential is a worthy...

Exploring the high-performance photoelectronic properties of perovskite quantum dots (QDs) is desirable for paper-based photoelectrochemical (PEC) sensing;however, challenges remain in improving their stability and fundamental performance. Herein, a novel Z-scheme heterostructure with host-guest interaction by the confinement of CH3NH3PbBr3 QDs within Cu3(BTC)2 metal-organic framework (MOF) crystal (MAPbBr3@Cu3(BTC)2) is successfully constructed on the paper-based PEC device for ultrasensitive detection of Ochratoxin A (OTA), with the assistance of the exciton-plasmon interaction (EPI) effect. The host-guest interaction is estabilished by encapsulating MAPbBr3 QDs as guests within Cu3(BTC)2 MOF as a host, which prevents MAPbBr3 QDs from being damaged in the polar system, offering access to long-term stability with high-performance PEC properties. Benefiting from the precise alignment of energy levels, the photogenerated charge carriers can migrate according to the Z-scheme charge-transfer pathway under the driving force of the internal electric field, achieving a high photoelectric conversion efficiency. Upon OTA recognition, the EPI effect is activated to modulate the exciton response in MAPbBr3 QDs by accelerating radiative decay, finally achieving sensitive OTA sensing with a detection limit of 0.017 pg mL-1. We believe this work renders new insight into designing host-guest Z-scheme heterojunctions in constructing the paper-based PEC sensing platforms for environmental monitoring.

Lead halide perovskites MAPbX3 (MA = CH3NH3 or Cs; X = I, Br, Cl) are well considered to be potential candidates for photocatalytic reaction due to its excellent photoelectrical properties, but they still suffer from the low charge separation efficiency and slow catalytic reaction dynamics. To tackle the drawbacks, herein, MAPbBr3/carbon sphere (CS) composite photocatalysts using glucose as the carbon source were elaborately designed and fabricated via a dry mechanochemical grinding process. The interfacial interaction Pb-O-C chemical bonds were constructed between MAPbBr3 and the carbon sphere surface containing organic functional groups. By optimizing the content of CSs, the enhanced photocatalytic degradation kinetic rate of Malachite Green (MG) pollutants (92% within 20 min) for MAPbBr3/CSx (x = 17 wt.%) is about 3.6-fold of that for pristine MAPbBr3, which is attributed to the corporative adsorption and enhanced carrier transportation and separation of MAPbBr3/CSx. Furthermore, the possible degradation mechanism was proposed on basis of the electrochemical, mass spectrometry and optical characterization results. Owing to the robust interfacial interaction, effective electron extraction rate (ket = 4.6 × 107 sec-1) from MAPbBr3 to CS can be established, which driven oxygen activation where superoxide radicals (•O2-) played an important role in MG degradation. It is expected that mechanochemistry strategy may provide a new route to design efficient lead halide perovskite-carbon or metal oxide or sulfide composite photocatalysts.

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%.