Photoelectrochemical performance of La3+-doped TiO2

La-doped TiO2 thin films on titanium substrates were prepared by the sol–gel method with titanium tetrachloride as a precursor and La2O3 as a source of lanthanum. The heat-treatment temperature dependence of the photoelectrochemical performance of the La-doped TiO2 film in 0.2 mol/L Na2SO4 was investigated by the MottSchottky equation, electrochemical impedance spectroscopy, and the open-circuit potential test. The results from the Mott-Schottky curves show that the obtained films all were n-type semiconductors, and the film at 300 °C had the highest conduction band position and the widest space charge layer. The electrochemical impendence spectroscopy（EIS） tests of the 300 °C film decreased most during the change from illuminated to dark. The potential of the La–TiO2 thin film electrode was the lowest after the 300 °C heat treatment. The open-circuit potential indicated that the photoelectrical performance of the La-TiO2 films was enhanced with the addition of the La element and the largest decline（837.8 mV） in the electrode potential was achieved with the 300 °C heat treatment.