Sol-gel preparation and visible light photocatalytic activity of nitrogen doped titania

Nitrogen-doped titania powders with different doped ratios (mole percentage of N/Ti: 5%, 10%, 15%, 20% and 25%) and different calcination temperatures (i.e. 400,500, 600 and 700 degrees C) were prepared by sol-gel method, and urea was used as the nitrogen source. The samples were characterized by X-ray diffraction, UV-visible absorption spectroscopy and transmission electron microscopy, and their visible light photocatalytic activities were investigated by degrading methyl orange solution, which was used as the simulation of organic wastewater. The results showed that all nitrogen doped TiO2 prepared in our experiment presented anatase crystal structure; the absorption edge of TiO2 shifted to longer wavelengths due to N-doping; compared with non-doped TiO2, nitrogen doping increased the crystal size of TiO2; N-doping significantly improved the photocatalytic activity of TiO2 under visible light irradiation in comparison with commercial catalyst P25. It is considered that the optimal doped ratio and calcination temperature is 10% and 500 degrees C, respectively in the present experimental conditions. (C) 2011 Published by Elsevier Ltd.