Structure Regulation And Gas-Solid Photocatalytic Reaction Mechanism Of Bismuth Photocatalytic Materials

With the rapid development of human society and the economy,the environment and energy crisis are imminent.The more typical one is the degradation and conversion of toxic gases and greenhouse gas CO₂ in the atmosphere.In recent years,researchers have adopted various technologies,such as physics,chemistry,and biodegradation,to solve the harm of pollutant molecules to the environment and humans,and are constantly looking for new energy sources to replace non-renewable ones.However,these methods all have high costs and aggravate the pollution problem.Photocatalytic technology has attracted attention because of its environmental protection and low cost.For instance,Photocatalytic technology can deal with pollutants in various complex backgrounds,split water to produce hydrogen and reduce CO₂ gas into multi-carbon energy substances.In the context of photocatalysis,the synthesis of photocatalysts has been vigorously developed.Among them,bismuth-based semiconductors have attracted attention because of their special layered structure and energy bandwidth.In order to improve its activity,stability,and selectivity in the gas-solid phase photocatalytic process,the deep mechanism between structure and photocatalytic performance still needs to be further analyzed.In this thesis,a series of different methods are used to construct the structure of bismuth-based materials.And the mechanism of gas-solid phase photocatalytic reaction is revealed with modern characterization techniques.Details are as follows:（1）（BiO）₂CO₃/β-Bi₂O₃ heterostructures are fabricated by a facile method,which realizes efficient charge transfer and promotes NO removal.A major challenge for photocatalytic NO removal is achieving catalytic stability while maintaining high conversion efficiency.Experimental results show that the heterojunction structure is beneficial to enhance the catalytic stability with interfacial charge transfer channels.In addition,the introduction of graphene quantum dots on the heterojunction structure further strengthens the interfacial charge transfer kinetics and finally realizes that by-products（NO₂）can gain electrons and be converted into final products（nitrite or nitrate）.This composite structure exhibits not only high NO removal activity but also maintains long-term stability under visible light.（2）Because of the thermodynamic stability and chemically inertness structure of CO₂,the catalytic activity and stability of photocatalytic CO₂ reduction are limited by high reaction barriers,resulting in low conversion efficiency of light energy to chemical energy.The rational design of the chemical environment on the catalyst surface is conducive to the reactant activation and ultimately enhances the photocatalytic activity.Therefore,we prepared Bi₅O₇I with porous morphology by template calcination.The Bi₅O₇I constructed by this preparation method contains charge-rich Bi^（3-x）+ions,which are beneficial to the adsorption and activation of CO₂,while BiOIO₃ is not.Therefore,Bi₅O₇I also exhibits better charge transfer properties and about twice the catalytic activity compared with BiOIO₃.