One-step hydrothermal preparation of TiO2/WO3 nanocomposite films on anodized stainless steel for photocatalytic degradation of organic pollutants

TiO2/WO3 nanocomposite film was deposited on anodized stainless steel by one step hydrothermal reaction. Polished stainless steel foil was anodized to form nanopore arrays on the surface that is favorable for the immobilization of photocatalyst. The TiO2/WO3 nanocomposite film prepared in 0.01 mol/L (NH4)2TiF6 and 0.0066 mol/L Na2WO4 solution at 120 °C for 3 h exhibits the maximum photocatalytic activity, which is five times higher than that of pure TiO2 film and eight times higher than that of pure WO3 film. As compared with the pure TiO2 film, the main absorption edge of the WO3/TiO2 nanocomposite film shifts toward visible region and the absorption intensity is obviously improved. The nanocomposite film has a preferable crystallinity of anatase TiO2 and the monoclinic WO3, as revealed by X-ray diffraction and X-ray photoelectron spectroscopy. Scanning electron microscopy images show that the nanocomposite film is homogenous in size distribution and uniform in morphology. The high resolution transmission electron microscopy images further demonstrate the formation of mixed crystal between WO3 and TiO2 nanoparticles. The excellent photocatalytic activity of the nanocomposite film should be attributed to the formation of heterojunction between TiO2 and WO3 nanoparticles that can facilitate the separation of photo-generated electron-hole pairs.