Preparation of CdS-containing silica-titania composites by the sol gel process

Silica-titania composite materials containing 20 mol% TiO2 were prepared by sol-gel process using tetraethoxysilane (TEOS) and titanium isopropoxide (Ti(OPr)(4)) as precursors. A two-stage hydrolysis procedure was performed in acid conditions for preparation of the TiO2-SiO2 oxides. Nanometer sized crystallites of CdS were incorporated into TiO2-SiO2 matrices by complex formation with thiourea, SC(NH2)(2). The influence of the preparation route and calcination temperature on the structural characteristics and physico-chemical properties of TiO2-SiO2 and CdS/TiO2-SiO2 materials was studied by means of nitrogen physisorption, X-ray diffraction, infrared spectroscopy and atomic force microscopy. The results indicate that anatase phase is stable at temperatures up to 600degreesC for TiO2-SiO2 matrices and the addition of CdS particles affects the system crystallization. (C) 2004 Published by Elsevier B.V.