Synthesis And Photocatalytic Property Of Metal Halide Perovskites And Their Complexes

Photocatalytic technology is considered to be one of the promising solutions to energy and environmental problems.So far,various materials have been used as photocatalysts for photocatalytic reactions.However,there are few reports on the use of perovskite compounds as photocatalysts.This type of material exhibits excellent photophysical properties,such as high absorption coefficient,broad absorption spectrum,high carrier mobility,and long carrier diffusion length.These features make perovskite materials expected to be used as photocatalysts for high efficiency Photochemical transformation.The synthesis of metal halide perovskite and its composite materials and the exploration of the performance of photocatalytic reactions have aroused the interest of more and more scientific researchers.This paper synthesizes metal halide perovskites and their composites with excellent photophysical properties.The physical and chemical properties of the perovskite and perovskite composite photocatalyst were characterized by powder X-ray diffraction,transmission electron microscopy,liquid ultraviolet,electron paramagnetic resonance and other test methods,and the photocatalysis of the synthesized materials was deeply explored.The nature of organic conversion reaction and its reaction mechanism.The specific content is as follows:1.The metal halide perovskite CsPbBr₃ was synthesized by a simple method under normal temperature conditions.The study of physicochemical properties shows that CsPbBr₃ exhibits a broad band of visible light absorption,with a strong absorption peak at 518 nm.We explored the photocatalytic reaction of CsPbBr₃ coupling thiol and olefin when using blue light emitting diode as the light source.The results of photocatalysis experiments show that CsPbBr₃ is a highly active and highly selective photocatalyst for heterogeneous mercapto-olefin coupling reaction,which provides a feasible scheme for the construction of C-S bonds.We verified the possible mechanism of the photocatalytic reaction by free radical quenching experiments,fluorescence quenching and in-situ electron paramagnetic resonance.The results show that CsPbBr₃ effectively oxidizes the thiol substrate in the system during the reaction to generate highly active sulfhydryl radical species,thereby achieving efficient preparation of thioolefin coupling products.2.We synthesized CsPbBr₃ and g-C₃N₄ by traditional thermal injection method to prepare CsPbBr₃/g-C₃N₄ complex.Physical and chemical properties studies have shown that CsPbBr₃/g-C₃N₄ has a wide absorption band in the visible light range,and its absorption edge is located at about 560 nm.We studied the photocatalytic reaction of reducing bromoacetophenone and its derivatives to acetophenone with CsPbBr₃/g-C₃N₄ as the photocatalyst and N,N-diisopropylethylamine（DIPEA）as the cocatalyst.The results of photocatalysis experiments show that CsPbBr₃/g-C₃N₄ has high catalytic activity and product selectivity for the reduction reaction of bromoacetophenone.Under optimized conditions,CsPbBr₃/g-C₃N₄-30% can completely reduce bromoacetophenone to acetophenone.The catalytic activity of the composite photocatalyst is significantly better than its components CsPbBr₃ and g-C₃N₄,and also higher than reported Noble metal complexes and organic dyes used in similar reactions.The photocatalytic reaction mechanism was verified by free radical quenching experiment.Experiments show that the interfacial recombination of CsPbBr₃ and g-C₃N₄ can effectively enhance the excited state charge separation and transfer,reduce bromoacetophenone to generate free radical species,and realize high-efficiency photocatalytic dehalogenation reaction.