Selective synthesis and visible-light photocatalytic activities of BiVO_4 with different crystalline phases

摘要

Tetragonal and monoclinic bismuth vanadate (BiVO_4) powders were selectively synthesized by aqueous processes. The characterizations of the as-prepared BiVO_4 powders were carried out by X-ray diffraction, nitrogen adsorption, scanning electron microscopy and UV-vis diffuse reflectance spectroscopy. The photocatalytic activities of different BiVO_4 samples were determined by degradation of methylene blue solution under visible-light irradiation (λ > 420 nm) and compared with that of TiO_2 (Degussa P25). The band gaps of the as-prepared BiVO_4 were determined from UV-vis diffuse reflectance spectra. It was found that monoclinic BiVO_4 with a band gap of 2.34eV showed higher photocatalytic activity than that of tetragonal BiVO_4 with a band gap of 3.11 eV.