Sol-gel S-doped TiO2 materials for environmental protection

Sol-gel processing is one of the most common methods to produce TiO2 photocatalysts in both forms of coatings and gels. The electrons and holes photogenerated in the TiO2 photocatalyst have strong reduction and oxidation power, being able to drive a variety of reactions. This property allows the efficient decomposition of air and water pollutants. The photocatalytic degradation of pollutants using TiO2 photocatalysts is very attractive for applications to environmental protection, as a possible alternative to conventional water treatment technologies. Impurity doping is one of the typical approaches to extend the spectral response of a wide band gap semiconductor to visible light. In the present work pure and S-doped TiO2 nanometer films prepared by the alkoxide route of the sol-gel process have been studied. The influence of dopant, number of coatings and thermal treatment on the films structure was determined. One had in view the structural evaluation and crystallization behavior with thermal treatment by DTA/TG analysis, FTIR, spectroellipsometry (SE) and XRD. The sol-gel films were tested for the degradation of chloride organic compounds from aqueous solution. The photocatalytic activity was improved due to S-addition. A chlorobenzene removal yield of 97% has been obtained. (C) 2007 Elsevier B.V. All rights reserved.