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

Abstract Silica–titania composite materials containing 20 mol% TiO 2 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 TiO 2 –SiO 2 oxides. Nanometer sized crystallites of CdS were incorporated into TiO 2 –SiO 2 matrices by complex formation with thiourea, SC(NH 2 ) 2 . The influence of the preparation route and calcination temperature on the structural characteristics and physico-chemical properties of TiO 2 –SiO 2 and CdS/TiO 2 –SiO 2 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 TiO 2 –SiO 2 matrices and the addition of CdS particles affects the system crystallization.