Construction Of Perovskite Based Heterojunctions And Their Performance In Photocatalysts No Removal

Currently,air pollution is one of the major challenges of the developing countries.Among them,NO from fossil fuel combustion and vehicle exhaust emissions are one of the main causes of acid rain and photochemical smog,which endanger ecological safety.Air pollution caused by pollutants such as NO is becoming increasingly serious,seriously affects the quality of life and health of human beings.Traditional technologies for NO purification include adsorption（such as activated carbon and silica gel）,thermal catalysis,biological treatment,and selective catalytic reduction technologies.However,such technologies have high costs and serious secondary pollution problems,so it is imperative to explore a new clean and efficient technology to completely remove air pollutants such as NO.In recent years,photocatalytic technology has shown unique advantages in this field.Photocatalysis can deeply oxidize air pollutants such as NO at room temperature with little secondary pollution,which has a broad application prospect in air pollution control.Meanwhile,conventional catalysts prevent the efficient photocatalytic oxidation of NO due to their high electron-hole complexation efficiency and low light absorption capacity.Therefore,new high-efficiency catalysts need to be developed.Metal halide perovskite materials with the ability to adjust their band gap by changing the composition of the halides（Cl,Br,and I）.Meanwhile,metal halide perovskites exhibit properties such as high optical absorption coefficient,high mobility,low exciton binding energy,long carrier lifetime,and good stability,which are of great interest in the field of photocatalysis.However,the weak visible light responsiveness of metal halide perovskite materials hinders their application in photocatalytic purification of NO.Therefore,we have improved the design of photocatalysts by constructing heterojunctions to improve the light absorption ability,promoting photogenerated charge separation,and inhibiting the recombination of electron-hole pairs.We try to introduce common photocatalysts such as（Bi O）₂CO₃ and g-C₃N₄ and other photocatalytic materials for enhancing the photoelectric properties of metal halide perovskite materials to show efficient photocatalytic performance.The main research of this work is as follows:（1）Cs₃Bi₂Cl₉/（Bi O）₂CO₃ heterojunctions were constructed by precipitation method,and a comprehensive study on the charge separation and surface interface reaction mechanism of the heterojunctions was carried out.Through the construction of perovskite-based heterojunctions,the visible light response range of the native photocatalytic material is expanded,and then the effective purification of NO is achieved.In addition,the mechanism of photocatalytic oxidation of NO is revealed by elucidating the electron transport pathways through a research model combining experiments and theoretical calculations.The built-in electric field generated by the heterojunction structure leads to the migration of photogenerated electrons from the conduction band of（Bi O）₂CO₃ to the conduction band of Cs₃Bi₂Cl₉,which inhibits the compounding of electron-hole pairs and promotes the separation of photogenerated carriers,thus realizing the efficient purification of NO by photocatalytic materials.Meanwhile,the in situ infrared technique was also used to monitor the NO adsorption and oxidation processes to further reveal the photocatalytic oxidation mechanism of NO on heterojunctions.（2）The precipitation method was used to construct heterojunction structures by compounding Cs₂Ag Sb Cl₆ with g-C₃N₄,and the morphological structure of the heterojunction and its optical properties were investigated.In addition,the activation of the heterojunction for the adsorption of nitrogen oxide,water molecules,and oxygen molecules was investigated by a combination of experiments and theoretical calculations,which showed the electron transport paths and explained the reasons for the enhanced photocatalytic performance.Meanwhile,the migration of photogenerated electrons through the conduction band Cs₂Ag Sb Cl₆ of g-C₃N₄ in the generated built-in electric field of the heterojunction material suppresses the compounding of electron-hole pairs and promotes the separation efficiency of photogenerated carriers.Because more photogenerated charges are involved in the reaction on its surface,the efficient purification of NO by photocatalytic materials is achieved.This work may provide a new idea for understanding the mechanism of heterojunction photocatalysis.