Résumé
The heterogeneous photocatalysis is now recognized as a promising process for outdoor and indoor air treatment and self-cleaning applications. A lot of photocatalytic materials have been developed for exterior building elements (tiles, glass, tents, plastic ?lms, panels) or interior furnishing (tiles, wallpapers, window blinds, paints, ?nish)[1]. These materials are for the most part based on TiO2 which is the most widely used photocatalyst due to several key advantages. TiO2 is indeed relatively inexpensive, safe, chemically stable, exhibits high photocatalytic activity and is compatible with traditional construction materials[2]. However, for some of the substrates, the high photocatalytic activity of TiO2 may lead to significant damage and coating development on these substrates needs to include a way to protect them from unwanted degradation reactions. In this study, it is intended to obtain photocatalytic TiO2 based coatings on flexible organic materials for building applications (textile or paper) and the substrate protection is provided by two different technological innovations. On the one side, micrometric TiO2/SiO2 particles obtained by sol-gel chemistry are introduced into the existing organic coating of the substrates and on the other side, a new coating including TiO2 particles into a hybrid sol (organic/inorganic) is developed to replace the existing organic coating. Characterization includes surface analysis techniques (SEM, XPS and ToF-SIMS), UV light irradiation tests of the coated substrates and photocatalytic tests, i.e. photocatalytic oxidation of a model pollutant (formic acid) and the standardized methylene blue test (ISO 10678). Results showed that TiO2/SiO2 micrometric particles and the hybrid sol included TiO2 Degussa P25 particles exhibit significant photocatalytic activities. In parallel, coating surface characterization demonstrated the importance of TiO2 surface availability. Relevant examples will be displayed to illustrate the complementarity of the various characterization results, including the influence of pre-treatments (thermal or UV) (TiO2 particles into a hybrid sol) and the accessibility of pollutants to TiO2 through mesoporous silica (TiO2/SiO2 particles). References [1]Y. Paz, Applied Catalysis B: Environmental, 99 (2010) 448. [2]J. Chen and C-S. Poon, Building and Environment, 44 (2009) 1899.