Enhancement of the Visible Light Photocatalytic Activity of C-Doped TiO2 Nanomaterials Prepared by a Green Synthetic Approach

Mesoporous C-doped TiO2 nanomaterials with an anatase phase are prepared by a one-pot green synthetic approach using sucrose as a carbon-doping source for the first time. A facile post-thermal treatment is employed to enhance visible light photocatalytic activity of the as-prepared photocatalyst. The enhancement effect of post-thermal treatment between 100 and 300 °C is proved by the photodegradation of gas-phase toluene, and the optimum temperature is 200 °C. Physicochemical properties of the samples are characterized in detail by X-ray diffraction, Raman spectroscopy, N2 adsorption–desorption isotherms, transmission electron microscopy, Fourier transform-infrared spectroscopy, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectroscopy, and photoluminescence. The results indicate that the promotive effect of the post-thermal treatment can be attributed to the changes of the catalysts' surface and optical properties. The results also show that the recombination of electron–hole pairs is effectively inhibited after thermal treatment due to the reduction of surface defects. The facile post-thermal treatment provides a new route for potential industrial applications of C-doped TiO2 nanomaterials prepared by a green approach owing to its low cost and easy scale-up.