NANOSTRUCTURED TITANIUM DIOXIDE MATERIALS HAVING LOW OPTICAL GAP AND PROCESS FOR THE PREPARATION THEREOF

摘要

The invention discloses a simple and economic thermal treatment in air allowing to obtain nanostructured TiO₂ film with an optical gap substantially close to 2 eV. This is achieved by the use of a cluster-assembled TiO₂ film obtained by supersonic cluster beam deposition. This system is characterized by a highly porous and defective structure allowing the efficient incorporation, during thermal treatment, of carbon containing volatile molecules present in air. Substitutional carbon atoms modify the electronic structure of TiO₂ nanoparticles, causing the narrowing of the optical gap in the range of visible wavelength. The thermal treatment does not destroy the nanostructure of the as-deposited films.