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International Journal of Photoenergy
Volume 5 (2003), Issue 2, Pages 95-98

Photocatalytic decomposition of fatty stains by TiO2 thin films

1Physique de la Matière Condensée, Ecole Polytechnique, Palaiseau cedex 91128, France
2Saint-Gobain Recherche, 39 Quai Lucien Lefranc, BP 135, Aubervilliers 93303, France

Copyright © 2003 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Anatase TiO2 nanoparticles have been prepared as aqueous colloidal solutions by a conventional sol-gel process. Thin films have been deposited onto glass substrates by dip-coating and eventually further crystallized by heat-treatment up to 300C. The effect of the TiO2 film thickness, porosity and particle size on the reaction kinetics has been studied as well as the starting thickness of the fatty acid layer. The photocatalytic activity of the films has been measured through the decomposition of artificial stains formed by fatty acids deposited onto the TiO2 layer (adipic or stearic acid). The kinetics of stain photodecomposition has been studied in details by in-situ infrared spectroscopy absorption studies. This allows to discuss the role of UV light absorption and the interdiffusion of radicals and oxygen across the interfaces. The mechanism for stain decomposition is shown to be associated to a shrinkage of the solid film at the surface of the porous oxide film after a diffusion of the excited radicals from the oxide.