Abstract: Nitrogendoped and pure TiO₂ photocatalysts were synthesized by precipitation method using TiCl₄ as titanium precursor. Both X-ray diffraction (XRD) and N₂ adsorptiondesorption isotherms show that the asprepared samples consis of anatase phase except for trace brookite phase with mesoporous structure. X-ray photoelectron spectroscopy(XPS) confirms that the incorporated nitrogen element exists as the chemical state of NO_x. The UV-Vis diffuse reflection absorption spectra (UV-Vis) reveal that the nitrogendoped TiO₂ shows a new absorption region at 400-550nm. The photocatalytic activities of the nitrogendoped TiO2 utilized for the photodegradation of 4-chlorophenol (4-CP) are higher than those of the pure TiO2 under UV and visible light irradiation. The improved photocatalytic activities under UV light irradiation of the nitrogendoped TiO₂ are attributed to the presence of NO_x. With no influence on the energy gap of TiO₂, NO_x can extend the optical response of TiO₂, excite more photoinduced electronsholes for photocatalysis and reduce the recombination probabilities of carriers.

Key words: titanium dioxide, nitrogendoped, photocatalysis, UV light