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 600 °C for TiO2–SiO2 matrices and the addition of CdS particles affects the system crystallization.