Optical, electrochemical and hydrophilic properties of Y2O3 doped TiO2 nanocomposite films.

The 5% Y2O3 doped TiO2 nanocomposite film (YTF) deposited on ITO glass substrate has been synthesized by the sol-gel dip-coating method. The as-synthesized samples were characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), voltage-current (V-I), electrochemical impedance spectroscopy (EIS) and ultraviolet-visible (UV-vis) analysis technologies. The crystalline structure, surface morphology and surface chemical composition of YTF sample have been primarily investigated. The results demonstrate that YTF is anatase crystalline phase with thickness of 480 nm and consists of spherical shape particles with a grain size of about 15.8 nm. The binding energy appears as a chemical shift, and relatively more Y and Ti species are present on the surface, indicating that active surfaces of the nanocomposite film have been enhanced with more oxygen vacancies Vö due to doping Y2O3 to TiO2. The absorption edge of YTF has a red shift, and the optical properties of YTF in visible light region have been obviously improved. The water contact angle is about 8 degrees after daylight lamp irradiation 60 min. An equivalent circuit model provided a reliable description for the electrochemical systems. Based on the Mott-Schottky equation, the donor concentration (ND) for YTF is 1.05 x 10(20) cm(-3), which enhances 1 order of magnitude than that for pure TiO2 film (TF), the flat-band potential (V(fb)) and the space charge layer (d(sc)) obviously decreased. With the incorporation of Y2O3 into TiO2, the optical, electrochemical and photoinduced hydrophilic properties of YTF in visible light region have obviously improved, indicating that YTF shows promising applications in solar energy conversion, self-cleaning and other potential fields.