Photocatalytic activity of BiVO4@TiO2 composite nanorods arrays

There is an enormous demand to develop novel TiO2-based photocatalytic material with higher photocatalytic activity due to its great performance in wastewater treatment. However, the exaggerated band gap of 3.2 eV for TiO2, which only absorbs the energy in the UV region, limits its application in wastewater treatment. In recent years, BiVO4 as a photocatalytic material has drawn considerable attention because of its appropriate ban gap of ~ 2.4 eV that allows a strong absorption in visible light region, excellent intrinsic charge transport properties, and suitable band location for recombination with other photocatalysts. In this paper, BiVO4@TiO2 nanorod arrays (NRAs) were fabricated on fluorine-doped tin oxide substrates via hydrothermal method, the structure and morphology of NRAs were observed by X-ray diffraction and scanning electron microscope, and the surface element and valence states were investigated by X-ray photoelectron spectroscopy. To confirm the improvement of photocatalytic performance after loading BiVO4 particles, methylene blue degradation test for before and after loading BiVO4 particle samples was carried out. The result indicates that the BiVO4@TiO2 NRAs sample shows a better degradation property than the single one, and the optimal parameter is 10 h with the concentration of 0.2 M. The capacity of photon carrier generation and electron–hole pairs migration was also investigated via UV–Vis diffuse reflection spectroscopy and photoluminescence spectra. The result illustrates that the absorption region is broadened by loading BiVO4 and the recombination of carriers is restrained efficiently, attributing to the transfer between TiO2 and BiVO4.