Synthesis of BiOBr, Bi3O4Br, and Bi12O17Br2 by controlled hydrothermal method and their photocatalytic properties

Bismuth oxybromides have received remarkable attention in recent years because of their stability, suitable band gaps, and relatively superior photocatalytic abilities. In the preparation procedure, BiBr3 is dissolved in an aqueous solution, NaOH aqueous solution is added to adjust the pH value, and then the aqueous solution is transferred into a 30 mL Teflon-lined autoclave, which is heated to 100–250 °C for 4, 6, and 12 h and then naturally cooled to room temperature. The composition and morphologies of bismuth oxybromides could be controlled by adjusting some growth parameters, including reaction pH, time, and temperature. The products are characterized by XRD, SEM-EDS, HR-TEM, DR-UV, BET, and HR-XPS. It is demonstrated that BiOBr, Bi3O4Br, and Bi12O17Br2 can be selectively prepared through a facile solution-based hydrothermal method. UV–vis spectra show the three materials being the indirect semiconductors with optical bandgaps of 2.85, 2.66, and 2.42 eV. Photocatalytic efficiency of the powder suspension is evaluated by measuring the crystal violet (CV) or salicylic acid (SA) concentration. This is a study to show the superior activities of BiOBr, Bi3O4Br, and Bi12O17Br2 as a promising visible-light-responsive photocatalyst.