Optical and Photocatalytic Properties of Cu-Cu2O/TiO2 Two-Layer Nanocomposite Films on Si Substrates

This paper introduced a process to prepare novel Cu-Cu2O/TiO2 two-layer nanocomposite films with Cu-Cu2O mixture layers grown on TiO2 films prepared by a magnetron sputtering method. The structure, the morphology and optical properties of the films were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), fluorescence spectroscopy (PL), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectroscopy (DRS). XRD patterns indicate that the Cu-Cu2O mixture layer does not change the crystalline phase of TiO2. XPS results show that the presence of Cu restrains the oxidation of Cu2O surface for Cu-Cu2O/TiO2 layer. SEM analysis reveals that the well crystallized Cu-Cu2O mixture nanoparticles are dispersed uniformly on the surface of TiO2. Owing to UV-vis diffuse reflectance spectroscopy, an red shift of the extended absorption edge of Cu-Cu2O/TiO2 takes place. PL spectra confirm the presence of Cu which reduces the recombination rate of exited electron-hole. Photocatalytic experiments demonstrate that compared with pure Cu2O/TiO2, the as-prepared Cu-Cu2O/TiO2-8 shows greater efficiency in photogenerated carriers and a significantly improved photocatalytic performance. In addition the reason for improvement in photocatalytic activity of the Cu-Cu2O/TiO2-8 films was also discussed.