Preparation of V-doped TiO2 photocatalysts by the solution combustion method and their visible light photocatalysis activities

A series of nanocrystalline V-doped (0.0–3.0 at.%) TiO₂ catalysts have been successfully prepared by the one-step solution combustion method using urea as a fuel. The obtained powders were characterized by XRD, SEM, Raman, XPS and UV-Vis DRS. The effects of V doping concentration on the phase structure and photocatalytic properties were investigated. XRD, Raman, and XPS show that V doping diffuses into TiO₂ crystal lattice mainly in the form of V⁵⁺ and causes a phase transition from anatase to rutile. V doping can widen the light absorption range of TiO₂, with the absorption threshold wavelength shifting from 425 to 625 nm. The photocatalytic activity of V-doped TiO₂ powders were evaluated by the photocatalytic degradation of methyl orange (MO) under visible light irradiation. It is found that V doping enhances the photocatalytic activity under visible light irradiation and the optimal degradation rate of MO is about 95.8% with 1.0 at% V-doped TiO₂.