Study On The Influence Of La～(3+),Cd～(2+) Doping On Methanol Photo-electrocatalytic Oxidation Of Nanometer TiO₂ Electrode

Among a number of nanometer semiconductors applied to the research of photocatalytic and solar cell field, nanometer TiO₂ is regarded as the most attractive material. But the absorption band of TiO₂ is only limited in ultraviolet region. That hinders its practical application. How to improve the conversion efficiency of light to electricity becomes the research hotspot. As for various kinds of ways to modify the surface of the catalyst, metal ion doping receives more and more attention. Study on the photoeletrocatalytic behavior of ion doping TiO₂ film electrode and the mechanism are informative to the increasement of the photoinduced electron efficiency. In this paper, La³⁺ or Cd²⁺ doped nanometer TiO₂ film electrode was prepared by improved sol-gel method and was applied to photocatalytic oxidation of methanol. The surface structure and the photocatalytic activities for oxidation of methanol of TiO₂ film electrode have been characterized by SEM, XRD, UV-via, CV and EIS. Influence of ion doping has been discussed. The main content is as follows:1. La³⁺ or Cd²⁺ doped TiO₂ film electrodes have been prepared with different contents, and applied to the photoelectrooxidation of methanol. The result shows that an appropriated doping amount of La³⁺ or Cd²⁺ can improve the photoelectrochemical activity. XRD SEM and CV characterization show that La³⁺ or Cd²⁺ doping changes the surface structure of TiO₂. UV-via absorption spectrum shows that the absorption band of doped TiO₂ film moves to longer wavelength. The La³⁺ or Cd²⁺ doping can increase the utilization of sunlight of TiO₂ film electrode.2. Proper calcining heat can cause the deficiency on the crystal surface partly. Thus the disorder on the surface of catalyzer is changed, which leads to the change of the catalytic activity and selectivity. Influence of different calcining heat on photochemical activity of the different ion doped electrode has been investigated. Under our present condition,0.5% doping, 450℃ and 400℃ calcining to La³⁺ and Cd²⁺ respectively ,are the optimum process parameters.