Preparation and characterization of S-doped TiO2 nanoparticles, effect of calcination temperature and evaluation of photocatalytic activity

S-doped TiO2 photocatalyst with high activity of visible light was prepared by modified sol–gel method using thiourea as sulfur source. The catalyst was characterized by XRD, FT-IR, DRS, SEM-EDX and TEM analysis. The undoped and S-doped TiO2 nanoparticles calcined at 500 °C contained only anatase phase. Effects of calcination temperature showed formation of rutile phase get started at 650–700 °C for undoped TiO2 and 750 °C for S-doped TiO2. The activity of the catalyst was examined by photodegradation of methyl orange in aqueous solution under both visible and UV light and it was found to be depending on the amount of S. The most activity was observed for 0.05% and 0.1% S-doped TiO2 under visible and UV light, respectively. Results showed for undoped TiO2, calcined samples at 650 and 550 °C under visible and UV light are the best catalysts, respectively. Also for 0.05% S-doped TiO2, calcined sample at 500 °C is the best catalyst under UV and visible light.