Study On Preparation And Photocatalytic Properties Of BiOBr-based Composites

With the continuous development of textile industry,dye wastewater has caused water pollution.Organic dyes such as methylene blue（MB）,methyl orange（MO）and tetracycline（TC）exist in dye wastewater.Photocatalysts can be used to degrade dye wastewater pollution.Bismuth bromide（BiOBr）is a narrow band gap visible light catalyst,but its photogenerated carriers（photogenerated electrons and holes）are easy to recombine,resulting in a decrease in photocatalytic performance.In this study,the semiconductor heterojunction was constructed by BiOBr and Ag₃PO₄,and the BiOBr/Ag₃PO₄ and BiOBr/Ag₃PO₄@rGO composite materials were prepared,which improved the separation efficiency of photogenerated carriers and further enhanced the catalytic activity.BiOBr/Ag₃PO₄ and BiOBr/Ag₃PO₄@rGO composites were prepared by hydrothermal method and chemical precipitation method.The principle of photocatalytic degradation of pollutants is that when visible light is irradiated,electrons on VB of BiOBr and Ag₃PO₄ will transition to CB and generate holes at the same time.Electrons on CB of BiOBr can reduce O2 to superoxide radicals（·O2-）,and holes on VB of Ag₃PO₄ can oxidize H2O to hydroxide radicals（·OH）.The generated·O2-,·OH and h+can oxidize MB,MO and TC into CO2 and H2O.The composition and morphology of the BiOBr-based photocatalyst were characterized by XRD,XPS,SEM,TEM,BET,FT-IR and Raman methods.The photocatalytic degradation efficiency of MB,MO and TC in water and the cyclic stability of the BiOBr-based photocatalyst were tested under visible light irradiation（300W xenon lamp,λ>420 nm）.The photocatalytic degradation effects of BiOBr/Ag₃PO₄ and BiOBr/Ag₃PO₄@rGO composites on MB,MO and TC are as follows:（1）The degradation efficiency for MB of BiOBr/Ag₃PO₄ composite under visible light irradiation for 30 min was 77.9%.After 60 min,the degradation efficiency of MO was 92.3%.After 24 min,the degradation efficiency of TC was 92.6%.（2）BiOBr/Ag₃PO₄@rGO composite material has a degradation efficiency of 97.4%for MB after 30 min under visible light irradiation.After 60 min,the degradation efficiency of MO was 99.1%.After 24 min,the degradation efficiency of TC was 98.5%.（3）The degradation efficiency of TC for the BiOBr/Ag₃PO₄ composite is 74.11%after four cycles under the irradiation of visible light,and the degradation efficiency of TC for the BiOBr/Ag₃PO₄@rGO composite is 95.06%.In summary,the photocatalytic degradation of MB,MO and TC by BiOBr-based nanocomposites is effective,which provides theoretical basis for the practical application of bio-br-based nanocomposites in degrading MB,MO and TC.