Preparation And Properties Of Bismuth Oxychloride-based Photocatalytic Materials

The rapid development of today's society and economy has brought many conveniences to our lives,but the resulting energy shortage and environmental pollution problems have seriously threatened human survival and development.With the maturity and development of photocatalytic technology,photocatalytic technology is considered to be one of the most promising methods to solve the energy and environmental problems facing humanity.Among them,bismuth oxychloride?BiOCl?photocatalyst has received extensive attention because of its excellent stability,good electron transportability,matt corrosion,and high photoactivity.However,BiOCl has the problems of large band gap,high photogenerated electron-hole recombination efficiency and low photon efficiency,so it has been limited in practical applications.In view of these characteristics of BiOCl,this article takes BiOCl as the research object,and acid red B?ARB?as the target degradation product.The photocatalytic activity was improved by modifying BiOCl through three methods:noble metal deposition,element doping,and heterojunction.The phase structure,micro-morphology,and photocatalytic performance of the samples were investigated.At the same time,the photocatalytic mechanism was preliminarily discussed,and the conclusions are as followed.?1?Using AgNO₃ as the Ag source,the Ag@BiOCl photocatalyst was prepared by depositing noble metal Ag on the surface of BiOCl by solvothermal method.Ag exists as spherical particles with a diameter of 40 nm.Based on the surface plasmon resonance effect?SPR?of Ag,the photoresponse range of BiOCl was successfully extended to the visible light region,which reduced the photo-generated electron-hole recombination efficiency and improved the charge transfer efficiency.The photocatalytic performance of Ag@BiOCl was studied under visible light.The results show that when the Ag content was 10wt%,it exhibited excellent degradation of ARB,and its degradation rate constant was 11 times larger than that of BiOCl.The active substance-capturing test results show that the main role in photocatalytic degradation of ARB is voids.?2?By using KI as the I source,a series of BiOCl_1-xI_x photocatalysts with different I^-doping levels were prepared by solvothermal method,and the photocatalytic degradation of ARB under visible light was studied.The results show that when x=0.4,the sample has the best photocatalytic performance,and the degradation reaction rate constant is 24 times that of BiOCl.The significant improvement in BiOCl_0.6I_0.4 photocatalytic activity can be attributed to the increase in specific surface area,the lower photoelectron-hole recombination efficiency,and the appropriate band gap width.The results of active species-capturing experiments show that oxygen holes are the main active species in the photocatalytic reaction process.?3?Heterojunction of TiO₂ mixed crystal and BiOCl_0.6I_0.4 was compounded to investigete its photocatalytic performance to ARB degradation under visible light.Firstly,using TiCl₄ and urea as raw materials,TiO₂ was prepared by hydrothermal method,and then BiOCl_0.6I_0.4/TiO₂was obtained by solvothermal method.The results show that when n?Ti?:n?Bi?=0.1,the sample has the highest photocatalytic activity.The degradation rate of ARB after 80 min of light exposure is 95%.The enhancement of its photocatalytic activity can be attributed to its higher specific surface area,higher charge transfer efficiency,and lower photo-generated electron-hole recombination rate.The results of free radical capture experiments show that in the process of photocatalytic degradation of ARB,the oxidation of hole is mainly dependent.