Fabrication And Photocatalytic Properties Of BiOBr And Its Composites

With the use of fossil fuel and running of high energy consumption and high pollution factories,the pollution of environment becomes worse and worse.The controlling of pollution is a global issue and must be managed worldwide.Out of many possible solutions,the semiconductor photocatalyst becomes the first selection to solve the pollution problem.Up to now,TiO2 has already been used broadly,because of its abundant reserves,cheap,stable chemical properties,non-toxic and other advantages.The band gap of TiO2 is about 3.20 eV,which correspond to ultraviolet range,therefor only 5% solar spectrum could be used,while BiOBr has a band gap of 2.64 eV,which promote the using efficiency of solar spectrum therefor BiOBr may be a potential high efficiency photocatalyst.In this work,BiOBr with three different morphologies was prepared through precipitation,and hydrothermal methods respectively.Besides,in order to improve the photocatalytic performance of BiOBr,three composites of BiVO₄/BiOBr,BiOBr-rGO,BiOBr/Ag₃PO₄ were prepared,and its photocatalytic properties were studied.The main results are as bellow:Nanoparticles and nanoflower like BiOBr were prepared by chemical precipitate.Nanosheet BiOBr was prepared through hydrothermal method.XRD results show that all BiOBr holds a same crystal structure of tetragonal phase.Among them,the nanoparticles of BiOBr exhibit the highest degradation efficiency of RhB under the radiation of ultraviolet and visible light.The composite BiVO₄/BiOBr was prepared through chemical precipitate BiOBr on BiVO₄ which is synthesized by hydrothermal method.XRD results show that the composites are a compound of tetragonal BiOBr and perovskite BiVO₄.The photocatalytic performance varies with the amount of BiVO₄,9 wt% BiVO₄/BiOBr exhibits the best photocatalytic performance of degraded RhB completely in 100 min under irradiation of ultraviolet and visible light.We believe this is mainly because of the existing of heterojunction in BiVO₄ andBiOBr interface which enhance the separation of light activated electrons and holes.The composite BiOBr-rGO was prepared through chemical precipitate BiOBr on rGO which is synthesized by improved Hummers method.BiOBr-rGO exhibits good photocatalytic performance and degrades RhB completely in 50 min under the irradiation of ultraviolet and visible light.The excellent photocatalytic properties come from the super-large specific surface area,which helps adsorb more RhB andthe prohibited recombination of electron and hole of rGO.The composite BiOBr/Ag₃PO₄ was prepared through chemical precipitate Ag₃PO₄ on BiOBr which is synthesized by hydrothermal method?XRD results show that composites are a compound of tetragonal BiOBr and a body-centered cubic Ag₃PO₄.0.5:1 BiOBr/Ag₃PO₄ composit exhibits the best photocatalytic performance of degrading RhB completely in 40 min under ultraviolet and visible light irradiation.We believe this is mainly because of the existing of heterojunction between BiOBr and Ag₃PO₄ interface which enhance the separation of light activated electrons and holes.