Search for content and authors

Transparent mesoporous nanocomposite films for self-cleaning applications

Morgan Gohin ,  Isabelle Maurin ,  Thierry Gacoin ,  Jean-Pierre Boilot 

Physique de la Matière Condensée, Ecole Polytechnique, CNRS, Palaiseau 91128, France


A versatile approach is studied for the elaboration of TiO2 based photocatalytic coatings for self-cleaning applications on transparent substrates. The basic principle of the synthesis relies on the use of preformed TiO2 colloidal particles that are further dispersed within a transparent silica binder with a mesoporous structure. Film porosity in the nanometer range is controlled by achieving the sol–gel silica condensation around self-organized micellar assemblies of a templating copolymer surfactant. The latter also acts as a stabilizer for the TiO2 particles, thus preserving their high dispersion within the film so that excellent optical properties are maintained even for high TiO2 loading (up to 50%).

The photocatalytic activity of the films was measured by monitoring the degradation of stearic acid deposited on the film under UV-A irradiation. Although the kinetics are found to follow a first order law over all the degradation curve, they exhibit a more complex behaviour, since the calculated rate constant k1 values calculated for different experiments were found to decrease drastically when increasing the initial stearic acid concentration.

Studies show that such mesoporous films are at least 15 times more active than films synthesized with a microporous silica binder. Moreover, the measured quantum-yield efficiency (1.1%) is found to be among the highest reported up to now. Improved photoactivity of the films is discussed as resulting from the closer proximity between the organic molecules and the surface of the TiO2 crystallites as well as the improved diffusion rate of water and oxygen through the interconnected pore network.

Legal notice
  • Legal notice:

Presentation: Oral at E-MRS Fall Meeting 2008, Symposium D, by Morgan Gohin
See On-line Journal of E-MRS Fall Meeting 2008

Submitted: 2008-05-09 10:15
Revised:   2009-06-07 00:48