Controlled hydrothermal synthesis of bismuth oxybromides and their photocatalytic properties

Ternary bismuth oxybromides have been synthesized using autoclave hydrothermal methods. The products are characterized by XRD, SEM-EDS, XPS, FTIR, and DRS. We demonstrate that Bi12O17Br2, Bi5O7Br, Bi3O4Br, Bi24O31Br10, Bi4O5Br2, and BiOBr can be selectively prepared through a facile solution-based hydrothermal method. UV-vis spectra show bismuth oxybromide materials to be indirect semiconductors with an optical band gap of 2.22-2.76 eV. Photocatalytic efficiencies of powder suspensions were evaluated by measuring the Crystal Violet (CV) concentration. This is the first study to show the superior activities of Bi12O17Br2, Bi5O7Br, Bi3O4Br, and Bi4O5Br2 as a promising visible-light-responsive photocatalyst. (C) 2013 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.