| Energy shortage and environmental pollution are two major problems facing human society.As a kind of inexhaustible clean energy,solar energy has been widely concerned and studied,and has made remarkable achievements in the field of solar cell and photocatalysis.Photocatalytic technology is a catalytic process that converts solar energy into chemical energy through semiconductor materials and which is widely used in the fields of hydrogen production and pollutant degradation.In recent years,a new type of photoelectric conversion semiconductor material has attracted people's attention,halogenated perovskite material.Compared with traditional semiconductor materials,halogenated perovskite has the advantages of wide absorption range,long carrier transport distance and long carrier life.However,perovskite materials are faced with two important problems,decomposition in water and toxicity of lead,which seriously restrict its practical application in production and life.At present,the research on non-lead perovskite materials has attracted more and more researcher's attention.The researchers attempted to replace Pb2+ with non-toxic or low-toxic ions such as Sn2+ and Bi3+,while maintaining the excellent photoelectric conversion performance of perovskite materials.After testing the photocatalytic properties of a series of lead-free perovskite materials,A3B2X9 perovskite materials were selected as the research object of this paper,and the photocatalytic performance of Cs3Bi2I9 and its solid solution Cs3Bi2xSb2-2xI9 was studied.In the first chapter,the properties and applications of halogenated perovskite materials,the prospects and limitations of semiconductor photocatalytic technology were briefly introduced.The research status and existing problems of lead-based halogenated perovskite materials in the field of photocatalytic decomposition of HI acids and the research progress of lead-free perovskite were introduced.In the second chapter,Sn-and Bi-perovskite powder materials were synthesized by super-saturation precipitation method,and their hydrogen production performance in the decomposition of hydroiodic acid was tested and compared with MAPbO3.By considering the catalytic performance and stability test,the Bi-based perovskite material Cs3Bi2I9 was selected as the next research objectIn the third chapter,Cs3Bi2I9 was taken as the research object to improve its catalytic performance from two aspects.On the one hand,the effect of Bi3+on hydrogen production was attenuated by ion regulation;on the other hand,the solid solution treatment of Cs3Bi2I9 and Cs3Sb2I9 reduced the carrier loss caused by their intrinsic defects.In the experiment,Cs3Bi0.6Sb1.4I9 solid solution materials were successfully prepared,and the hydrogen production rate of Cs3Bio.6Sb1.4I9 reached 926 mol g-1 h-1,which was comparable to the photocatalytic performance of MAPbI3/rGO.This was the first time that the performance of lead-free perovskite could reach the level of lead-based perovskiteIn the fourth chapter,we tested the degradation performance of Cs3Bi2xSb2-2xBr9.In order to further study the properties of solid solution perovskite,Cs3Bi2xSb2-2xBr9 was synthesized by saturated solution precipitation and applied to the degradation of organic dyes.The better photocatalytic performance of the solid solution was further verified by studying the crystal structure,morphology distribution and light absorption of the solid solutionIn the fifth chapter,the research content of this paper is summarized,the shortcomings are given,and the future work is forecasted.This thesis aims to solve the problem of Pb toxicity in perovskite.The photocatalytic performance of Bi-based perovskite material was greatly improved by means of loading and doping commonly used in the field of photocatalysis.It provides a new thought and direction for the following research on lead-free perovskite materials. |
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