Surface/interface Modulation And Photocatalytic Performance Of The BiOX(CI,I)Composites

Energy crisis and environmental pollution have threatened the sustainable development of society being.Semiconductor photocatalysis has attracted greater interesting because it canutilize the ennergy of natural sunlight to solve energy supply and environmental pollution problems.However,photocatalysis also suffered from a hurdle of low quantum efficiency when only singlesemiconductor was used as photocatalyst due to the fast electron-hole recombination rate and limited harvesting of visible light.The key method of resolving the problems above is to construct photocatalytic composites which have potential application in the photocatalysis field because it can improve the low quantum efficiency and poor visible light utilization of single semiconductor photocatalyst.The efficient separation and migration of photogenerated charge carriers in the suface/interface of composites determine the photocatalytic activity of composite semiconductor photocatalysts,while the structure and property of composites suface/interface is a pivotal role that influence the photogenerated charge transport behavior.Therefore,to reasonably and effectively control the surface/interface of composites can enhance photogenerated charge transport and photocatalytic performance.Baseon the basic scientific problems above,our work was performed around constructing photocatalytic composites,aiming at high quantum efficiency and really solving the problemsabout single photocatalyst.This thesis select BiOX(Cl,I)as research substratewhichcan be constructed semiconductor heterojunction and designed rational composite structures.Then,photocatalytic watersplitting and photocatalyticbacteria inactivation as a modelreaction was used to evaluate the photocatalytic properties of the compositematerials.The structure active relationship of each unit in the composite structures was studied by combining various physical and chemical methods.Moreover,the mechanism of photocatalysis was also elucidated and verified.Our work include two main research contents:(1)BiOCl/Bi3O4Cl ultra-thin nanosheet heterojunction photocatalyst was prepared by one-step hydrothermal and mechanical stripping inthe organicsolution.The addition of alkaline solution dissolved partial BiOCl precursors,and provided a two-dimensional growth template for Bi3O4Cl growth.The mainly research of charge bluk-phase migrationeffected on the transportof photogenerated carriersand photocatalytic watersplitting efficiency.(2)Ag/AgI/Bi-BiOI 3Dnano-architectures,synthesized by solvothermal reaction and photoreduction method,were used as high effective visible light driven photocatalystsfor the inactivation of Escherichia coli K-12.The main results following:(1)The formation of BiOCl/Bi3O4Cl ultra-thin nanosheet heterojunction,to form a strong built-in electric field in its interface,exposed to the {001}active crystal face and compared to non-ultra-thin plate heterojunction structure,could more effectively accelerate the separation and migration of photogenerated carriers.These reasons can contribute to enhance the activity of photocatalytic oxygen production which is 10 times higher than that of conventional nanoplate heterojunctions.(2)Thedesignof Ag/AgI/Bi-BiOI composite photocatalyststhatpromoted the transfer of photogenerated charges more efficiently by controlling the charge transfer pathwhereAg was used as a "Z"type carrier-mediated in this composite structure.The composites exhibited more bacteria disinfection efficiency,and thequantity of viable bacteria could almost inactivate after being illuminated for 18 min,moreover,revealing the pivotal roles of h+,e-,and ·O2-in the photocatalytic process.These results not only extend the application value of composite photocatalytic materials in the field of photocatalysis,but also have important scientific and practical significance and further promote the mechanism of photocataysis reaction and its theoretical basis.