Synthesis of nanoporous tio2 thin films for photocatalytic degradation of methylene blue

This work reports a structure and photocatalytic activity of nanoporous titania (TiO₂) thin films by an anodizing approach. Xray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) studies showed that tetragonal anatase was the main phase in the thin films that consisted of countless disordered nanopores in the order of 10 to 15 nm. In the photocatalytic degradation of methylene blue, the titania thin films showed a good photocatalytic activity. 82.2 % methylene blue could be photodegraded by titania thin films with UV radiation. XPS results indicate that during the degradation of methylene blue, some Ti³⁺ may be partially oxidized to Ti⁴⁺ in the TiO₂ films and the surface hydroxyls directly participate in the reaction. Our nanoporous titania thin films is commensurable to Degussa-25 TiO₂ powders because the latter requires filtration in each treatment; it is also much superior to the direct photolysis approach with respect to photoactivity.