Visible Light Induced Photocatalytic Activity of N-doped TiO2

Photocatalytic properties of nitrogen doped titanium dioxide were investigated. Photocatalytic degradation of methylene blue under UV and visible light was carried out to characterize N-doped TiO2. The result of XPS indicated that nitrogen atoms substitute for oxygen sites within the crystal structure of TiO2. In the UV-Vis DRS spectra, N-doped amorphous TiO2 absorbed UV light with little absorption of visible light, while the absorption of visible light of amorphous/anatase TiO2 remarkably increased. Methylene blue photocatalytic degradation appeared by the irradiation of UV or visible light onto the N-doped anatase phase of TiO2. However, the degradation rate of visible light was lower than that of UV light. The photocatalytic degradation rate of the amorphous/anatase TiO2 sample was higher than that of the anatase TiO2. These results indicate that the high surface area of amorphous/anatase TiO2 sample, which was about three times larger than those of the anatase TiO2 sample, may be related to small particles of N-doped anatase TiO2.