Formation of anatase nanocrystals in sol-gel derived TiO2-SiO2 thin films with hot water treatment

We have successfully prepared transparent and porous anatase nanocrystals-d ispersed films by treating the sol-gel derived TiO2-SiO2 films containing p oly(ethylene glycol), PEG, with hot water. This process was done at tempera tures lower than 100 degreesC under atmospheric pressure, and thus anatase nanocrystals-dispersed films can be formed on various kinds of substrates i ncluding organic polymers with poor heat resistance. The changes in structu re and composition of the TiO2-SiO2 gel films with hot water treatment were related to the formation process of anatase nanocrystals in the TiO2-SiO2 gel films with hot water treatment. The formation of anatase nanocrystals w as found to proceed to hydrolysis of Si-O-Ti bonds and dissolution of SiO2 component. In addition, porous film structure formed by leaching of PEG wit h hot water treatment led to homogenous dispersion of anatase nonocrystals in the films.