Highly efficient visible light TiO 2 photocatalyst prepared by sol–gel method at temperatures lower than 300 °C

Abstract

Highly efficient visible light TiO 2 photocatalyst was prepared by the sol–gel method at lower temperature (≤300 °C), and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), UV–vis diffuse reflectance spectroscopy (UV–vis DRS), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and differential scanning calorimetry-thermogravimetric analysis (DSC–TGA). The effects of the heat treatment temperature and time of the as-prepared TiO 2 on its visible light photocatalytic activity were investigated by monitoring the degradation of methyl orange solution under visible light irradiation (wavelength ≥ 400 nm). Results show that the as-prepared TiO 2 nanoparticles possess an anatase phase and mesoporous structure with carbon self-doping and visible photosensitive organic groups. The visible light photocatalytic activity of the as-prepared TiO 2 is greatly higher than those of the commercial TiO 2 (P-25) and other visible photocatalysts reported in literature (such as PPy/TiO 2, P3HT/TiO 2, PANI/TiO 2, N–TiO 2 and Fe 3+–TiO 2) and its photocatalytic stability is excellent. The reasons for improving the visible light photocatalytic activity of the as-prepared TiO 2 can be explained by carbon self-doping and a large amount of visible photosensitive groups existing in the as-prepared TiO 2. The apparent optical thickness ( τ app), local volumetric rate of photo absorption (LVRPA) and kinetic constant ( k T ) of the photodegradation system were calculated.