A shuriken-shaped m-BiVO4/{0 0 1}–TiO2 heterojunction: Synthesis, structure and enhanced visible light photocatalytic activity

Shuriken-shaped BiVO4/TiO2 composite with heterojunction structure was synthesized by a facile hydrothermal reaction. The photocatalyst was characterized by X-ray diffraction, transmission electron microscopy, high resolution transmission electron microscopy, UV-vis diffuse reflectance spectra, N-2 adsorption/desorption, X-ray photoelectron spectroscopy techniques, photoluminescence spectra and photoelectrochemical measurements. The photocatalytic activities were evaluated by the degradation of methyl blue (MB) under visible light irradiation. The results indicated that the synthesized monoclinic BiVO4 had a shuriken shape. The TiO2 nanosheets (NSs) with dominant {0 0 1} facets adhered uniformly on the surface of BiVO4, forming the heterojunction structure. The obtained BiVO4/TiO2 showed about 1.4 times and 8.9 times higher photocatalytic activity than that of the bare BiVO4 and physical mixture BiVO2_TiO2 sample, respectively, which can be attributed to the synergistic effect of BiVO4/TiO2 heterojunction and TiO2 NSs. The incorporation of TiO2 not only did not affect the visible light absorption ability of BiVO4, but also improved the specific surface area as well as pore diameter, which suggesting a better adsorption ability for pollutants. More importantly, the formed heterojunction between m-BiVO4 and TiO2 significantly improved the separation efficiency of the photogenerated electron-hole pairs. These factors contribute to the enhancement of photocatalytic activity. A possible mechanism was also proposed to understand the origin of enhanced performance in the heterojunction system. (C) 2015 Elsevier B.V. All rights reserved.