Preparation And Photocatalytic Property Of N-Doped And N-Fe Codoped TiO₂Thin Films

With the advantage of high photocatalytic activity, no toxicity and low cost, TiO2photocatalyst has broad prospects in antimicrobial, degradation of harmful organic pollutants and air purification.However, TiO2could only be activated by ultraviolet light (λ≤387nm), but there is only4percent of ultraviolet light in the sunlight, making the low utilization of solar energy. Therefore, narrowing the band gap of TiO2is a hot point in the research of photocatalyst in recent years.Doping properly with other elements is an effective means to make TiO2with visible light photocatalytic activity. In this paper, we prepared the N-doped and N-Fe co-doped TiO2thin films by anodic oxidation and electrophoretic deposition method, and studied the composition, structure and photocatalytic properties of the films. The exact work is as following:(1) TiN film was deposited on the surface of Ti foil by electrophoretic depositing method with a Ti plate as an anode and a platinum plate as a cathode in aqueous suspension of10g/L TiN. N-doped TiO2film was formed by annealing TiN film at different temperature in air. The transition temperature from anatase to rutile phase of the TiO2film is between500-600℃. The band gap of the N-doped TiO2thin film formed by annealing at500℃decreased to2.96eV and the UV-visible absorption edge showed obvious red shift compared with that of the undoped TiO2. The efficient degradation of methylene blue with N-doped TiO2thin films under visible irradiation was observed.(2) N-Fe codoped TiO2films were prepared by anodic oxidation of the TiN films. During the sample preparation, the TiN film was as an anode, a platinum plate was as a cathode in aqueous suspension of0.5wt%HF and0.1mol/L Fe (NO3)3. Then the films were annealed at300-600℃in air. N-Fe co-doped TiO2thin films with nanoporous surface were formed. Red shifts were observed for the UV-visible absorption edges of the N-Fe co-doped TiO2films. The band gap of the N-Fe co-doped TiO2film formed by annealing at500℃decreased to2.51eV, and the film showed obvious visible light catalytic degradation of methylene blue.