The effect of Bi content on the photocatalytic performance of bismuth oxybromides

BiOBr, Bi₃O₄Br and Bi₄O₅Br₂ were prepared by hydrothermal and solvothermal methods. Their structural composition, surface morphology, chemical states and optical properties were characterized by XRD, SEM, XPS and UV-vis. The band structure and density of states of the photocatalysts were calculated by density functional theory (DFT). The photocatalytic activity was evaluated by degradation of RhB. The results show that band gap and the position of conduction band is affected by Bi content. The Bi₄O₅Br₂ photocatalyst can completely degrade RhB in 50 min. Radical-trapping experiments proves that · \rmO_2^- is the main active species in photocatalytic degradation of RhB.