Facile synthesis of SiO2@TiO2 crystallite photocatalysts with enhanced interaction level and high light absorption efficiency

Abstract

SiO 2 @TiO 2 crystallite photocatalysts with TiO 2 crystallite core and porous amorphous SiO 2 /TiO 2 shell were synthesized as photocatalyst by one-pot hydrothermal process using tetrabutyl titanate (TBOT) complex and ethyl orthosilicate (TEOS) as Ti and Si sources, respectively. The synthesized SiO 2 @TiO 2 crystallite photocatalysts were characterized by transmission electron microscopy, X-ray diffraction pattern, UV-Vis diffuse reflectance spectrum and N 2 adsorption-desorption isotherm. The interaction between TiO 2 and SiO 2 , which is associated with photocatalytically active centers, is significantly improved through an enlargement in the interfacial area and the optimization of SiO 2 fraction. The SiO 2 modification does not lower the light absorption efficiency of TiO 2 crystallite core owning to the low reflectivity of porous SiO 2 /TiO 2 shell but endows the photocatalyst with easy separation behavior from aqueous solution. Furthermore, the reciprocal inhibition in volume shrinkage of TBOT complex-and TEOS-derived gel networks, as a consequence of mineralization asynchronism, increases the specific surface area and pore volume of the formed SiO 2 / TiO 2 shell. The enhanced photocatalytic activity of SiO 2 @TiO 2 crystallite photocatalysts by SiO 2 modification is mainly ascribed to an increase in the interaction level, the high light absorption efficiency of SiO 2 @TiO 2 crystallite photocatalysts and an enlargement in specific surface area of SiO 2 /TiO 2 shell.