Characterization of self-standing Ti-containing porous silica thin films and their reactivity for the photocatalytic reduction of CO 2 with H 2O

Abstract

Self-standing porous silica thin films with different pore structures were synthesized by a solvent evaporation method and used as photocatalysts for the photocatalytic reduction of CO 2 with H 2O at 323 K. UV irradiation of these Ti-containing porous silica thin films in the presence of CO 2 and H 2O led to the formation of CH 4 and CH 3OH as well as CO and O 2 as minor products. Such thin films having hexagonal pore structure exhibited higher photocatalytic reactivity than the Ti-MCM-41 powder catalyst even with the same pore structure. From FTIR investigations, it was found that these Ti-containing porous silica thin films had different concentrations of surface OH groups and showed different adsorption properties for the H 2O molecules toward the catalyst surface. Furthermore, the concentration of the surface OH groups was found to play a role in the selectivity for the formation of CH 3OH.