Photocatalytic reduction of CO2 with H2O on titanium oxides anchored within zeolites

Titanium oxide species anchored within the zeolite cavities and framework by an ion-exchange method and a hydrothermal synthesis exhibit high and unique photocatalytic reactivity for the reduction of CO2 with H2O at 328 K with a high selectivity for the formation of CH3OH in the gas phase. In situ photoluminescence, ESR, diffuse reflectance absorption and XAFS investigations indicate that the titanium oxide species are highly dispersed within the zeolite cavities and framework and exist in tetrahedral coordination. The charge transfer excited state of the highly dispersed titanium oxide species plays a significant role in the reduction of CO2 with H2O exhibiting a high selectivity for the formation of CH3OH, while the catalysts involving the aggregated octahedrally coordinated titanium oxide species show a high selectivity to produce CH4.