The Preparation of a novel Composite Film Based on Polyoxometalate for visible light photocatalysis

摘要

The composite film, FeW_(11)O_(39)~(9-)(FeW_(11))/TiO_2/SiO_2, was prepared by liquid phase deposition method (LPD) at low processing temperature for the first time. Formation of the stable composite film is due to strong chemical reaction of ≡Ti-OH from TiO_2/SiO_2 with the surface oxygen atoms at vacant sites of FeW_(11). The structural properties of the film were characterized using FT-IR, UV-vis spectra, Elemental Analysis. The experimental results confirmed the retention of the primary Keggin structure and the saturation of the surface of the lacunary FeW_(11); Formation of Ti-O-Si bond implies that the TiO_2 crystallites highly dispersed on the silica surface via oxygen as a bridge. The catalytic activity was tested by the photo-degradation of aqueous azo dye congo red (CR) (0-20 mmol·L~(-1)). The resulting film exhibited efficient visible-light photocatalytic activity to decompose aqueous azo dye CR, which is mainly attributed to long time existence of Fenton-assisted FeW_(11)/TiO_2/SiO_2 excitation state. According to the experimental results, a synergistic effect mechanism of the photodegradation process is proposed.