Synthesis of mesoporous nitrogen-tungsten co-doped TiO2 photocatalysts with high visible light activity

Mesoporous N,W co-doped TiO2 photocatalysts that contained various percentages of atomic tungsten dopant levels were synthesized by a facile solution combustion method which utilized urea as a nitrogen source and sodium tungstate as a tungsten source. The prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), N-2 physisorption, UV-vis absorbance spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results reveal that the synthesized N and W co-doped TiO2 nanomaterials have high surface areas and mesoporous structures. In addition, the co-doping significantly narrows the band gap (similar to 2.7 eV) that is responsible for the high visible light response of these samples in comparison to that of pure anatase TiO2 (similar to 3.2 eV). The photocatalytic activity of the prepared samples was evaluated on the basis of the photodegradation rate of Rhodamine B under visible light (lambda > 420). It was found that the mesoporous N,W co-doped TiO2 nanomaterials fabricated in this study exhibited high visible light activity. This significant improvement in photocatalytic activity may be attributed to the synergistic effect of the red shift in absorption combined with a high surface area. (C) 2011 Elsevier B.V. All rights reserved.