Abstract
Anatase-type TiO2 / SiO2 composite particles were directly synthesized as combination of nanometer-sized anatase particles and amorphous silica from solutions of TiOSO4 and tetraethylorthosilicate by hydrolysis under hydrothermal condition at 200°C. The composites possessed far more improved photocatalytic activity and phase stability than pure anatase-type TiO2. By making composite with SiO2 and with increasing SiO2 content, onset of optical absorption of anatase was slightly shifted to shorter wavelengths and its photocatalytic activity and phase stability were considerably enhanced. In the composite containing 48.2 mol% SiO2, crystallite size (15-16 nm) of as-prepared anatase was maintained after heating at 1000°C, and the anatase phase existed up to 1300°C without appearance of a trace of rutile phase.
