Titania Nanocrystals-Dispersed Coatings from SiO2-TiO2 Gel Films through Hydrolysis and Dissolution
Anatase nanocrystals were formed on sol-gel derived SiO2-TiO2 coatings with water vapor or hot water treatments. The anatase nanocrystals were precipitated through hydrolysis of Si-O-Ti bonds, dissolution of SiO2 component, migration of hydrolyzed titania species, and nucleation and growth. The process temperatures can be lowered below 60oC, which should open new applications. It was found that the crystal habit of titania was changes from roundish anatase to sheet-like titania by applying vibration during the hot water treatment. The nanosheets were identified as hydrated titania, TiO2 . mH2O, with layerd structure. The coatings of hydrated titania showed high photocatalytic activities and excellent antifogging properties due to their unique morphology.
T. Ohji, T. Sekino and K. Niihara
A. Matsuda et al., "Titania Nanocrystals-Dispersed Coatings from SiO2-TiO2 Gel Films through Hydrolysis and Dissolution", Key Engineering Materials, Vols. 317-318, pp. 565-568, 2006