Photocurrent response and photocatalytic activity of Nd-doped TiO2 thin films prepared by sol-gel method

The undoped and Nd-doped TiO2 thin films were prepared on indium-tin oxide (ITO) conductive glass by sol-gel method using dip-coating technique. The crystal structure, surface morphology, composition and surface chemical state of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS), respectively. The results show that the undoped and Nd-doped TiO2 form anatase structure after calcining at 450 degrees C for 2 h and the crystalline size of TiO2 decreases by Nd doping. The photocurrent response of the thin films was tested by electrochemical workstation. The results show that all the Nd-doped TiO2 thin film electrodes demonstrate higher photocurrent response. The photocurrent density of Nd-doped TiO2 thin film electrodes increases at first and then decreases with the dopant concentration increasing from 0.5 at.% to 4 at.%. The maximum photocurrent density is obtained on 1 at.% Nd-doped TiO2 thin film electrode, which is 3.2 times higher than that obtained on undoped TiO2 thin film electrode. The photocatalytic activity of films was investigated by the degradation of methylene blue (MB). The results reveal that higher photocurrent causes higher photocatalytic activity. The degradation rate of 1 at.% Nd-doped TiO2 thin film increases about 60 % than that of undoped TiO2 thin film.