Relationship of Photo-electrochemical Behavior and Photocatalytic Activity of TiO_2 Thin Film Manipulatively Doped by Ni

The thin films of TiO2 doped manipulatively by Ni were prepared by a section-controlled process of sol-gel method. The activity of thin films was characterized by photocatalytic degradation of aqueous methyl orange under UV irradiation. The results showed that the photocatalytic activity of TiO2 thin film remarkably enhanced by non-uniformly doping, whereas that of the uniformly doped improved a little. The photo-electrochemistry behaviors of the thin films were studied by electrochemical workstation. The results showed that the non-uniformly doped TiO2 thin film displayed higher photocurrent compared with that of the pure one and the uniformly doped, which demonstrated that the photogenerated electron-hole pairs were effectively separated within the non-uniformly doped TiO2 thin film. The cyclic voltammetry curves revealed the oxidation-reduction potential shift in the reaction system of the non-uniformly doped TiO2 thin film under UV irradiation, which indicated that the inner electric field formed. Based on the p-n junction theory of the semiconductor, the photocatalytic activity mechanism of the non-uniformly doped TiO2 thin films was discussed.