Enhanced Photocatalytic Activity of Co Surface Doped Nanocrystalline TiO2-SiO2 Composite Films

In order to enhance the photocatalytic activity of the TiO₂ films, Co surface doped TiO₂-SiO₂ composite films were synthesized by the improved sol-gel method, in which tetrabutyl titanate (Ti(OC₄H₉)₄) and tetraethyl orthosilicate were chosen as the precursors and cobaltous nitrate hexahydrate (Co(NO₃)₂·6H₂O) was chosen as cobalt source. The field emission scanning electron microscopy and X-ray diffraction results indicated that the films were composed of nanoparticles or aggregates. The photoluminescence results revealed that the recombination rate of the photogenerated electrons and holes was prohibited via SiO₂ composite and Co doping in TiO₂ film. The Brunauer?CEmmett?CTeller results showed that the surface area of the modified TiO₂ was 301.7?m²?g^?1, while that of the pure TiO₂ was 68.4?m²?g^?1. The photocatalytic activities of the films were evaluated by degradation of an organic dye in aqueous solution. With the SiO₂ composite and Co doping, the modified TiO₂ films with high photocatalytic activity and clearly responsive to the visible light were obtained. The mechanisms of photoactivity enhancement for composite films have also been discussed.