Reduction of aqueous CO2 at ambient temperature using zero-valent iron-based composites

The reduction of CO2 was investigated over zero-valent Fe-0 and Fe-0-based composites in an aqueous solution at room temperature. It was found that H-2 and a small amount of CH4 were formed from the CO2-H2O-Fe-0 system, while no H-2 was formed without CO2. When potassium-promoted Fe-0-based composites, Fe-0-K-Al and Fe-0-Cu-K-Al, were used, the CO2 reduction rates were increased and CH4, C3H8, CH3OH, and C2H5OH were produced together with H-s. The fresh and used Fe-0 powders after the reaction were analyzed by XPS, XRD, and photoemission yield measurements. The obtained results suggest that in the presence of CO2 as a proton source zero-valent Fe-0 is readily oxidized to produce H-2 stoichiometrically and that CO2 is reduced catalytically over the Fe-0-based composites with the resulting H-2 to produce hydrocarbons and alcohols.