Sol–gel derived S,I-codoped mesoporous TiO2 photocatalyst with high visible-light photocatalytic activity Original Research Article

A mesoporous S,I-codoped TiO2 photocatalyst with high visible light photocatalytic activity was synthesized through the hydrolysis and condensation of titanium isopropoxide with thiourea and iodic acid as the precursors. The as-prepared catalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV–vis diffuse reflectance (DRS), X-ray photoelectron spectroscopy (XPS), Fourier translation infrared spectroscopy (FT-IR), and N2 adsorption. The results showed that the cations of S6+ and I5+ could substitute for some of the lattice titanium (Ti4+). The S,I-codoping forms the new bands above the valence band and narrows the band-gap of the TiO2, then shifts the absorption edge from UV light region to visible light range. The activity of the catalyst was examined by photodegradation of methylene blue in an aqueous solution under visible light irradiation. The activity of the S,I-codoped catalyst is far superior to that of single S or I-doped TiO2 counterpart. The high visible light photocatalytic activity could be attributed to the strong absorption of light, well-crystalline anatase phase, and mesoporous microstructure.