Efficient degradation of organic pollutant with WOx modified nano TiO2 under visible irradiation

摘要

Nanocrystalline tungsten oxide-doped titanium dioxide (WOx-TiO2) powders were prepared by a sol-mixing method. The photooxidation efficiencies of WOx-TiO2 catalysts were evaluated by conducting a set of experiments of photodegrading Methylene blue (MB) in aqueous solution. The experiments demonstrated that the MB in aqueous solution was successfully degraded usingWO(x)-TiO2 under visible light irradiation, especially when the pH value of the solution was over 6. It was found that an optimal WO, dosage of 1% in WOx-TiO2 achieved the highest photocatalytic activity in the conditions of this experiment, on which MB was photooxided completely within 1 h. Powders were characterized by X-ray diffraction (XRD), X-ray photoelectron emission spectroscopy (XPS), UV-vis absorption spectra, transmission electron micrograph (TEM) measurements. These results showed that tungsten oxides not only hindered the growth of TiO2 particles but 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 because of the similarity in the ion radius of Wn+ and Ti4+ to form non-stiochiometric solid solution of WxTi1-xO2. The light absorption band of TiO2 changed from the near UV to the visible light range (2.98 eV in 1.0% WOx-TiO2) because of the tungsten impurity energy level induced by WxTi1-xO2. (c) 2006 Elsevier B.V. All rights reserved.