Photocatalytic reduction of CO2 with H2O on various titanium oxide photocatalysts

The specific features of the photocatalytic reduction of CO2 with H2O on various types of active titanium oxide catalysts are reviewed. UV-light irradiation of the bulk TiO2 powders in the presence of CO2 and H2O at room temperature under heterogeneous gas-solid conditions produced CH4 as the major product, while the predominant formations of CH3OH as well as CH4 were observed on the highly dispersed titanium oxide moiety anchored on zeolites and mesoporous silica materials. The CH3OH formation is originated from the unique properties of the charge transfer excited state, i.e., (Ti3+–O−)* of the tetrahedrally-coordinated titanium oxide species within the silica frameworks.