Preparation of nitrogen-doped titania and its photocatalytic activity

Yellowish nitrogen-doped titania was produced through sol-gel method in mild condition, with the elemental nitrogen derived from aqua ammonia. The titania catalysts were characterized using XRD, BET, TEM, XPS, and UV-Vis diffuse reflectance spectrophotometer, and their photocatalytic activities were evaluated under UV and visible fight, respectively. The XRD results showed that all titania catalysts were anatase. More significantly, the crystallite size of nitrogen-doped titania increased with an increase in N/Ti proportion, and the doping of nitrogen could extend the absorption shoulder into the visible-light region, thus it possessed a higher visible-light activity illustrated by decolorization of methyl orange (65.3%) under the irradiation of visible fight, whereas pure titania showed little of such kind of visible light activity. The UV-Iight activity of nitrogen-doped titania catalysts was worse than that of pure titania and Degussa P25. In the range of N/Ti proportion of 4-10 mol%, the activity of nitrogen-doped titania weakened appreciably in the visible-light region as the N/Ti proportion increased, whereas a reverse relationship existed under the irradiation of UV light.