Preparation of WOx-TiO2 and the photocatalytic activity under visible irradiation

Nanocrystalline tungsten oxide doped titanium dioxide (WOx-TiO2) powders were prepared by TiCl4 hydrolysis and characterized by XRD, XPS, UV-Vis absorption spectra and TEM. Results showed that WO, not only hindered the growth of TiO2 particles but also greatly increased the transformation temperature (>800 degrees C) from anatase to rutile during sintering; the dominant fraction of tungsten oxides was non-stoichiometric tungsten oxide (WxOy) with Wn+ (4<n<6), which could easily substitute Ti4+ in the lattice of TiO2. The light absorption band of TiO2 changed from the near UV to the visible light range (2.68 eV in 1.0 %WOx-TiO2) because of the tungsten impurity energy level induced by WxTi1-xO2. The photocatalysis experiments demonstrated that the MB in aqueous solution was successfully degraded within 1h using WOx-TiO2 with an optimal WOx dosage of 1% under visible light irradiation.