Simple and effective preparation and characterization of nitrogen-doped TiO_2 nanocrystallites and their visible light activities

Nitrogen-doped TiO2 nano-sized photocatalysts were prepared by a simple acid-catalyzed sol-gel method using urea as nitrogen raw material.The photocatalytic decomposition of methyl orange in aqueous solution was used as a probe reaction to evaluate their photocatalytic activities under visible light irradiation.The prepared nitrogen-doped TiO2 samples on the crystallite sizes,cystal pattern,suface composition and optical absorption property were characterized by means of the techniques such as XRD,XPS and UV-Vis DRS spectra.The results showed that doping nitrogen in TiO2 reduces its band gap energy,which makes nitrogen-doped TiO2 nanocrystallites have a stronger visible light absorption from 400 to 530nm.Also they have high visible light photocatalytic activities in the degradation of methyl orange.The crystallite size of single anatase TiO1.9904N0.0096calcined at 400℃ was 14.94nm and exhibited the highest visible light photocatalytic activity.