A rapid microwave synthesis of nanoscale BiVO4/Bi2O3@SiO2with large specific surface area and excellent visible-light-driven activity

The photocatalyst BiVO4/Bi2O3@SiO2nanoparticle was synthesized in a high-pressured microwave method. The as-prepared photocatalytst was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV–Vis diffuse reflectance spectroscopy. The visible-light-driven activity of the prepared photocatalyst was evaluated by degradation of Rhodamine B (RhB). The results show that the as-prepared sample appears in a core-shell structure with the heterojunction BiVO4/Bi2O3as core and amorphous porous SiO2as shell. BiVO4/Bi2O3@SiO2has a large specific surface area (99.63 m2g–1) and exhibits superior photocatalytic activity in the degradation of RhB under visible-light illumination. The degradation rate constant of RhB over BiVO4/Bi2O3@SiO2are 9.8, 9.0, 8.4, and 5.6 times as high as that over Bi2O3, BiVO4, BiVO4/Bi2O3and BiVO4/SiO2, respectively. The enhanced photocatalytic activity of BiVO4/Bi2O3@SiO2is attributed to both high surface area and low recombination rate of photoinduced electron–hole pairs. The high surface area provides more active sites and superior adsorption properties, which promotes the photocatalytic activity. The low recombination rate of photoinduced electron–hole pairs is due to both the hetero-junction between BiVO4and Bi2O3and the presence of impurity level of SiO2.