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.