Low Temperature Hydrothermal Synthesis of Visible-Light-Activated I-Doped TiO2 for Improved Dye Degradation.

Iodine doped TiO2 with different iodine/Ti molar ratios has been firstly synthesized with a low temperature hydrothermal route and has been studied systematically in photocatalysis under visible light condition. The resulting iodine doped TiO2 were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (TEM), diffuse reflectance spectrum (DRS), and X-ray photoelectron spectroscopy (XPS). The photocatalytic performance investigations were conducted by means of the degradation of Rhodamine B (RhB) under the visible light irradiation in aqueous solution. Under an optimized I/Ti doping ratio of 10 mol%, the photocatalytic performance is greatly better, with degradation efficiency of 95%, which is almost double that of pure TiO2. The superior photocatalytic activity of iodine-doped TiO2 could be mainly attributed to extended visible light absorption originated from the formation of continuous states existed in the band gap of the doped TiO2 introduced by iodine. Active oxygen species, that is, *OH and O2-, were evidenced to be involved in the degradation process and a possible mechanism was also proposed.