Preparation And Performance Study Of Bismuth Bromide Oxide Based Composite Photocatalytic Materials

With the advent of modern society,water resources are facing many challenges.Advanced oxidation processes（AOPs）,as a key method,have been widely used to degrade various non biodegradable pollutants in water and wastewater by producing high oxidizing substances.Multiphase photocatalysis,as one of the feasible,green,and most advantageous methods,has attracted widespread attention due to its ability to completely degrade different pollutants under environmental conditions.In recent years,bismuth halide oxide compounds（Bi OX,X=F,Cl,Br,I）have become a research hotspot in the field of photocatalysis due to their effectiveness in degrading organic pollutants.Among them,p-type BiOBr has a unique layered structure and indirect transition band gap,with a suitable band gap（2.7 e V）and the best photocatalytic redox activity under full spectrum irradiation.In addition,compared to traditional catalysts and oxidants,BiOBr has a higher valence band position,indicating its stronger oxidation ability.However,the high recombination rate of internal electron hole pairs in BiOBr cannot be ignored.The preparation of BiOBr based composite photocatalysts can overcome its own shortcomings and achieve better photocatalytic performance.This article uses hydrothermal and solvothermal methods to prepare three different structures and characteristics of photocatalysts:ZnO/BiOBr,ZnO/BiOBr/g-C₃N₄,and Bi/BiOBr/ZnO.Their optical properties,photocatalytic performance,and catalytic mechanism were studied.1.Using hydrothermal method,ZnO/BiOBr composite photocatalysts with molar ratios of 0.5:1,1:1,and 2:1 were prepared.Research has shown that a 1:1 BiOBr/ZnO sample has the best photocatalytic activity,and after 40 minutes of light irradiation,the degradation efficiency of MO is close to 94%.After three cycles of reusing,the degradation efficiency still remains 88%,indicating good reusability.2.ZnO/BiOBr/g-C₃N₄composite material was prepared by hydrothermal method,and the sample with a g-C₃N₄content of 50%（ZBC-50）exhibited the best photocatalytic performance.Within 20 minutes,the photocatalytic degradation rate of MO reached 100%,which was 10.7 times that of BiOBr,25 times that of ZnO,69times that of g-C₃N₄,and 2.5 times that of BiOBr/ZnO,respectively.Meanwhile,ZnO/BiOBr/g-C₃N₄photocatalyst exhibits good recovery efficiency.3.Bi/BiOBr/ZnO composite photocatalyst was prepared using a hydrothermal/solvothermal synthesis method.The photocatalytic efficiency of the composite sample has been greatly improved,with a degradation rate of 94%within20 minutes.Its degradation rate is 19 times that of ZnO,8 times that of BiOBr,and 2times that of BiOBr/ZnO.The improvement of photocatalytic efficiency is attributed to the promoting effect of heterostructures on the separation of photo generated electrons/holes.This work lays the foundation for the synthesis of bismuth based photocatalysts and their application in wastewater treatment.