Preparation of Porous SiO2-TiO2 Nanocomposites and Their Photocatalytic Activity

Porous SiO2-TiO2 nanocomposites were synthesized by utilizing TiO2 nanopartilces obtained by a sol-gel method, followed by an impregnation process with F127 modified SiO2 sol. The resulting samples were characterized by XRD, BET, TEM, N2 adsorptiona2desorption, UV-Vis DRS spectra and FT-IR spectra, and their photocatalytic activities were also evaluated by degrading RhB solution under illumination. The effects of the SiO2 on the thermal stability and photocatalytic activity of anatase nanoparticles were mainly investigated. The results show that the SiO2 can greatly enhance the thermal stability of TiO2 crystallities, even having a principal anatase phase composition after heata2treated at 900 and make TiO2 maintain a small crystallite size. The large surface area of the resulting SiO2-TiO2 nanocomposites is attributed to the small crystallite size and porous SiO2. During the processes of photocatalytic degradation RhB, all the asa2prepared SiO2-TiO2 nanocomposites by thermal treatment at high temperature exhibit higher activity than Degussa P-25 TiO2. The high activity is attributed to the high anatase crystallinity and the large surface area.