Abstract: Nitrogen and nickel co-doped TiO₂ photocatalyst was synthesized by the combination of precipita-tion with layer-by-layer impregnation, in which titanium tetrachloride was used as Ti-precursor and ammonia, nickel chloride as doping-ion donors. The samples were characterized by means of X-ray diffraction(XRD), nitrogen adsorption-desorption, X-ray photoelectron spectroscopy(XPS) and UV-Vis spectroscopy(UV-Vis). The as-prepared photocatalyst was dominantly in anatase phase and a mesoporous structure. The doped nitrogen and nickel impurities were found to be NO_x and Ni₂O₃, NiO species, which were confirmed by XPS. The photocatalytic activity of co-doped TiO₂ was higher than that of both pure and single doped one. Visible light response was due to NO_x and the doped nickel maintains the charge balance at the same time. Simul-taneously, the special concentration gradient distribution of Ni in this work reduced the possibility of recom-bination of photogenerated holes and electrons, which seemed to contribute to the enhancement of the photo-catalytic activity of nitrogen and nickel co-doped TiO₂.

Key words: Photocatalysis, Titanium dioxide, Nitrogen and nickel co-doping, Visible light, Impregnation method