A novel Bi-based oxybromide Bi4NbO8Br: Synthesis, characterization and visible-light-active photocatalytic activity

A novel visible-light-driven Bi-based layered photocatalyst Bi4NbO8Br was successfully prepared by a solid state reaction. The calcination temperature was found to play an important role in controlling synthesis of Bi4NbO8Br, and pure Bi4NbO8Br can only be obtained at 700 °C–800 °C. The as-prepared samples were characterized by XRD, SEM, DRS and PL. Bi4NbO8Br has an indirect-transition optical band-gap of 2.34 eV, and the ECB and EVB are estimated to be 0.63 eV and 2.97 eV, respectively. The photocatalytic activities of the samples were determined by decomposition of rhodamine-B (RhB) in aqueous solution under visible light illumination. The results revealed that the sample calcinated at 750 °C exhibited the highest photocatalytic activity among the pure Bi4NbO8Br samples. The sample calcinated at 850 °C, composed of BiNbO4 and Bi4NbO8Br, showed higher photocatalytic activity than that calcinated at 750 °C, which may be due to the formation of heterostructure.