New TiO 2/SiO 2 nanocomposites—Phase transformations and photocatalytic studies

Abstract

A series of TiO 2/SiO 2 nanocomposites were synthesized via a novel sol–gel method. A phase transformation study of as-synthesized nanocomposite due to thermal treatment up to 1100 °C has showed the existence of anatase phase in all the tested temperatures. At thermal treatment, when the temperature exceeded 400 °C, brookite phase was formed beside anatase phase. At 950 °C, the amorphous silica matrix was transformed to crystobalite and the brookite phase disappeared. Finally, the small peaks of rutile phase were detectable at 1100 °C. The presence of tetrahedral coordination of TiO 2 in SiO 2 matrix was confirmed by UV–vis study. The produced nanocomposites have good photocatalytic properties due to its anatase phase, tetrahedral coordination of TiO 2 in SiO 2 matrix and very large surface area. The photocatalytic properties of the composites were compared for the degradation of Congo Red (CR) azo dye. Further studies were also devised to compare the catalytic efficiency of the composite with the synthesized pure TiO 2. The results revealed that the as-prepared composite is the most effective.