Physicochemical properties and photocatalytic activities of TiO2-films prepared by sol–gel methods

The physicochemical properties, the photocatalytic activities in aqueous solution and the adhesion properties of supported TiO2 films prepared by different sol–gel methods have been studied. The thickness, the TiO2 loading and the photocatalytic activities are influenced by the nature of the stabilising agent. By contrast, the nature of the organic titanium precursor, as well as the solvent and the absence of stabilising agents are determining for the resulting photocatalytic activities. Titania-sol generated by non-controlled hydrolysis of titanium isopropoxide was used to determine the influence (i) of number of coating, (ii) of the calcination temperature and (iii) of the nature of support on the photocatalytic activity under direct and backside irradiation. The higher the coating number, the thicker the TiO2-film and the higher the photocatalytic efficiency. the optimum calcination temperature was found to be 400 °C. Migration of cationic species into TiO2-films and the decrease of thickness at higher temperatures lead to the decline of activity.