Preparation And Performance Study Of BiOBr Based Photocatalytic Materials

In this thesis,using bismuth bromide oxide（BiOBr）as the main material,firstly,the effect of morphology on the photocatalytic degradation efficiency of the organic dye rhodamine B（Rh B）was investigated by preparing BiOBr monomers with different morphologies.Secondly,we constructed binary Ag₂MoO₄/BiOBr composite heterojunction photocatalysts and investigated their performance in the photocatalytic degradation of methylene blue（MB）.Thirdly,the ternary Ag/In₂S₃/BiOBr composite photocatalyst was obtained by using silver（Ag）nanoparticles,which were synergistically modified with indium sulfide（In₂S₃）to obtain ternary Ag/In₂S₃/BiOBr composite photocatalyst,and its photocatalytic degradation performance was investigated with ciprofloxacin（CIP）as the target degradant.A series of characterizations such as X-ray diffraction（XRD）,UV-vis diffuse reflectance spectroscopy（UV-vis DRS）and scanning electron microscopy（SEM）were performed on the samples,and the photoelectrochemical and photocatalytic properties of the samples were tested to reveal the photocatalytic mechanism of the prepared heterojunctions.The details of the study are as follows:（1）BiOBr monomers with different morphologies were prepared by the solvothermal method using NaBr and Bi（NO₃）₃·5H₂O as the bromine and bismuth sources,respectively.The photodegradation activity of the BiOBr samples with different morphologies was evaluated by degrading Rh B aqueous solution and detecting the concentration of Rh B aqueous solution based on UV-vis absorption spectroscopy measurements.The synthesized BiOBr nanostructures exhibited different photocatalytic activities,and the hollow microspheres BiOBr showed excellent photocatalytic degradation activity for Rh B aqueous solution.The effects of p H,initial concentration of Rh B and various anions on the photodegradation of Rh B were also investigated,and finally,the photocatalytic mechanism was analyzed.（2）A novel Z-type Ag₂MoO₄/BiOBr composite heterojunction photocatalyst was constructed by assembling Ag₂MoO₄ nanoparticles onto BiOBr nanosheets by hydrothermal method.The photocatalytic degradation of MB was carried out under simulated sunlight and visible light irradiation,and the photocatalytic performance of the Ag₂MoO₄/BiOBr complex was evaluated.photodegradation experiments of MB showed that the photocatalytic activity of the 20%Ag₂MoO₄/BiOBr heterojunction was significantly higher than that of the monomer and other ratios of the samples.Z-type carrier transfer separation mechanism and explain the mechanism of its enhanced photocatalytic activity.Its practical application in the removal of environmental pollutants is also extended by degrading various organic pollutants,including organic dyes and antibiotics.（3）In₂S₃/BiOBr binary composite photocatalyst was obtained by co-precipitation method by depositing In₂S₃ nanoparticles on BiOBr nanosheets,and then,Ag nanoparticles were modified on the surface of In₂S₃ nanoparticles in In₂S₃/BiOBr composite photocatalyst by photoreduction method to construct ternary composite photocatalyst Ag/In₂S₃/BiOBr with ciprofloxacin（CIP）as the target pollutant,and the photocatalytic performance of the products was evaluated under simulated sunlight irradiation.The experimental results showed that the catalytic activity of the Ag/In₂S₃/BiOBr ternary composite photocatalyst was significantly higher than that of the monomeric and binary complexes.The improved photocatalytic activity can be attributed to three aspects:the formation of a Z-type heterojunction between In₂S₃and BiOBr,which promotes the separation of photogenerated carriers;the formation of a Schottky junction between Ag nanoparticles and In₂S₃,which plays the role of conduction and electron capture;and the SPR effect generated by Ag nanoparticles,which generates hot electrons and enhances the amount of charge involved in the photocatalytic reaction.