Preparation of nitrogen-doped titania with visible-light activity and its application

In order to utilize visible light in a photocatalytic reaction, yellow nitrogen-doped titania was prepared by sol–gel method in mild condition, with the elemental nitrogen source from ammonium carbonate. The catalysts were characterized by XRD, BET, and UV–vis diffuse reflectance spectrophotometry. The analytical results demonstrated that all catalysts were anatase, and the crystallite size of nitrogen-doped titania increased with increasing N/Ti proportioning, and the doping of nitrogen could enlarge the specific surface, extending the absorption shoulder into the visible-light region. Photocatalytic activity of the nitrogen-doped titania catalysts was evaluated based on the photodegradation of methyl orange and 2-mercaptobenzothiazole in aqueous solution under visible light. The effect of preparation conditions such as N/Ti proportion and calcination temperature on the visible-light activity was also discussed. The experiments demonstrated that the nitrogen-doped titania with N/Ti proportioning of 20 mol% calcined at 400 °C exhibited the highest visible-light activity. It was concluded that the enhancement of methyl orange and 2-mercaptobenzothiazole photodegradation using the nitrogen-doped titania catalysts is mainly involved in the enhancement of the separation of electron–hole pairs owing to the presence of Ti3+, the improvement of the organic substrate adsorption in catalysts suspension and optical response in visible-light region.