Photocatalytic property of SiO2/TiO2 nanoparticles prepared by sol-hydrothermal process

Abstract

Silica-embedded nanocrystalline TiO2 powders were synthesized by sol-hydrothermal process. The influence of the composition of the solvent and the embedded silica content on the phase transition, grain growth and subsequently, on the photoactivity of TiO2 were investigated. The volume ratio of ethanol to water for the solvent composition was varied from 0.125 to 8 and the mole fraction of silica content was changed from 0 to 0.4, while the condition for hydrothermal reaction was fixed at 250∘C for 2 hour. With an increase in ethanol content in solvent composition, the crystallite sizes of pure TiO2 particles decreased from 15 nm to 6 nm and crystal phase changed from rutile/anatase mixed phase to pure anatase phase. Addition of silica to TiO2 brought about an increase in the photocatalytic activity by suppressing the phase transition from anatase to rutile. Judging from the result of the decomposition of 1, 4-dichlorobenzene, the most efficient catalyst was found to be 0.2 mole fraction SiO2 embedded TiO2 prepared with ethanol-rich solvent (the volume ratio of ethanol to water is 4).