Effect of Vanadium(IV)-Doping on the Visible Light-Induced Catalytic Activity of Titanium Dioxide Catalysts for Methylene Blue Degradation

Vanadium(IV)-doped titanium dioxide (TiO2) photocatalyst powders were prepared by the sol-gel method and characterized by Brunauer-Emmett-Teller-specific surface area, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and ultraviolet-visible spectroscopy. V-doping in the TiO2 increases the crystal grain size, which decreases the specific surface areas of powders. This V-doping changes the band gap of TiO2, leading to extend the absorption to visible light regions (400-800 nm). Photocatalytic degradation of methylene blue (MB) in water was investigated as a function of the vanadium content in TiO2 and was found to follow pseudo first-order rate kinetics. Appropriate content of V-doping is an effective means to improve the photocatalytic activity of TiO2 for MB degradation under visible light irradiation.