Preparation of visible-light responsive N-F-codoped TiO2 photocatalyst by a sol-gel-solvothermal method

Anatase type N-F-codoped TiO2 powder was successfully prepared by a sol-gel-solvothermal method using tetrabutyl titanate as precursor. The effect of acidity and solvents on crystallinity, morphology, and size of the prepared N-F-TiO2 powder particles was investigated. The prepared catalysts were characterized by X-ray diffraction (XRD), thermogravimetry-differential thermal analysis (TG-DTA), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflection spectroscopy (UV-vis-DRS). The photo-catalytic activity of N-F-TiO2 powder was measured by using the reaction of photocatalytic degradation of p-chlorophenol. It was shown that the surface of N-F-TiO2 powder was strongly acidic, and it was confirmed that the N-F-codoped TiO2 powder showed strong visible-light absorption and high photocatalytic activity for p-chlorophenol and Rhodamine B under visible light irradiation (400-500 nm). The catalyst showed very high visible-light activity toward photocatalytic degradation of p-chlorophenol. Under the irradiation of 150 W tungsten halogen light for 12 h, the conversion could be as high as 17.8%, which was 1.75, 1.25 and 1.5 times higher than that of commercial P25 TiO2, N-TiO2, and F-TiO2 powder in a suspension system, respectively. The high visible-light photocatalytic activity of the N-F-codoped TiO2 may result from the generation of additional band of N 2p in the forbidden band, and the synergetic effect of nitrogen and fluorine doped. © 2006 Elsevier B.V. All rights reserved.