Abstract:

In order to expand the optical response of titania into the visible-light region，nitrogen·doped titania po w-ders with urea as the nitrogen source were prepared by sol-gel method in mild conditions.The prepared samples were then characterized using XRD,TEM,UV-Vis difuse reflectance spectrophotometer and X-ray photoelectron spectroscopy.Moreover,the photocatalytic activities of the sam ples in the visible-light region were tested,and the influences of calcination temperature and nitrogen content on the photocatalytic activity were investigated.Th e re-suits indicate that(1)the doping of nitrogen leads to an increase in optical absorption intensity in the visible-light region.which results in a high visible-light photocatalytic activity with nitrogen-doped titania in the decolouration of methyl orange;(2)with the increase in calcination temperature,the nitrogen content decreases,the crystallite size enlarges,and the visible-light photocatalytic activity weakens;and(3)there exists an optimum N/Ti proportion for the catalysts calcined at 400 ℃ ,which results in the highest visible-light photoctalytic activity。

Key words: titania, photocatalysis, nitrogen doping, visible light