TANG Yu-chao^1,2*,  HUANG Xian-huai¹,  LI Wei-hua^1

(1.Department of Environmental Science and Engineering, Anhui University of Architecture, Hefei 230022, P R China; 2. School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, P R China)

Abstract: Nitrogen doped dioxide titanium photocatalysts (N/ TiO₂) had been prepared by various methods: hydrolysis of tetrabutyl titanate (N/ TiO₂-H), ammonia thermal treatment of titanium dioxide (N/ TiO₂-A), mechanochemica1 treatment of titanium dioxide (N/ TiO₂-M) and urea thermal treatment of Ti(OH)₄ (N/ TiO₂-T). Results of UV-Vis-DRS indicated there had obvious onset of visible light absorption at 490nm of catalysts N/ TiO₂-H and N/ TiO₂-T, which initiated by impurity energy level located at above valance band formed by doped nitrogen. Excitations from localized states to the conduction band account for the absorption edge shift toward lower energies (visible region) observed in the case of N/ TiO₂ with respect to pure TiO₂. Mixture of visible light absorption of nitrogen doping and oxygen defect gave no obvious onset in the whole range between 400 and 800nm were observed of the samples N/ TiO₂-A and N/ TiO₂-M. Impurity energy level located at 0.75eV above valance band of TiO₂ calculated by theoretical method, which was well corresponding to experimental UV-Vis-DRS results. Binding energy of N 1s at about 399eV for all N/ TiO₂ catalysts were observed and there corresponding to interstitial nitrogen. Binding energy of Ti 2p and O 1s were increased about 0.3~0.6eV and 0.2~0.5eV respectively of various nitrogen doped TiO₂ with respect to pure TiO₂. These results indicated the doped mechanism of nitrogen in the TiO₂ was interstitial nitrogen.

Key words: Titanium Dioxide; Photocatalysis; Nitrogen; Interstitial; UV-VIS-DRS, XPS; Impurity Energy Level

E-mail: tangyc@mai.l ustc. edu. cn.

Journal of Molecular Catalysis, Vol. 24, Issue 4, 2010, 363~371