Microstructures and photo-catalytic properties of B³⁺and F⁻co-doped TiO₂films

The nano-crystalline B3+ and F− co-doped titanium dioxide films were successfully prepared by the improved sol–gel process. The as-prepared specimens were characterised using X-ray diffraction (XRD), high-resolution field emission scanning electron microscopy (FE-SEM), the Brunauer–Emmett–Teller (BET) surface area, X-ray photo-electron spectroscopy, photoluminescence spectra and UV–Vis diffuse reflectance spectroscopy. The photo-catalytic activities of the films were evaluated by degradation of an organic dye in aqueous solution. The results of XRD, FE-SEM and BET analysis indicated that the TiO2 films were composed of nano-particles. B3+ and F− co-doping could obviously not only suppress the formation of brookite phase but also inhibit the transformation of anatase to rutile at high temperature. Diffuse reflectance measurements showed that co-doping could clearly extend the absorbance spectra of TiO2 into visible region. Compared with pure TiO2, B3+ doped or F− doped TiO2 film, the B3+ and F− co-doped TiO2 film exhibited excellent photo-catalytic activity. It is believed that the surface microstructure of the films and the doping methods of the two ions are responsible for improving the photo-catalytic activity.