Photocatalytic oxidation activity of titanium dioxide film enhanced by Mn non-uniform doping

The thin films of TiO2 doped by Mn non-uniformly were prepared by sol-gel method under process control. Each film was characterized by XPS, SEM, UV-vis spectrophotometry and electrochemistry workstation analysis. The activity of the photocatalyst was evaluated by the kinetics of photocatalytic degradation of aqueous methyl orange under the UV radiation. The results show that Mn non-uniform doping evidently enhances the photocatalytic activity of TiO2 thin film. In 80 min, the degradation rates of aqueous methyl orange are 62%, 12% and 34% for Mn non-uniformly doped film (0.7%), the uniformly doped film (0.7%) and pure titanium dioxide film, respectively. The characteristic of PN junction in the film was proved by electrochemical characterization. A mechanism for enhanced photocatalytic activity of Mn non-uniformly doped titanium dioxide film was discussed based on the effective separation of the photon-generated carrier because of the existence of the PN junction.