Reduction of aqueous CO2 at ambient temperature using zero-valent iron-based composites
The reduction of CO2 was investigated over zero-valent Fe0 and Fe0-based composites in an aqueous solution at room temperature. It was found that H2 and a small amount of CH4 were formed from the CO2–H2O–Fe0 system, while no H2 was formed without CO2. When potassium-promoted Fe0-based composites, Fe0–K–Al and Fe0–Cu–K–Al, were used, the CO2 reduction rates were increased and CH4, C3H8, CH3OH, and C2H5OH were produced together with H2. The fresh and used Fe0 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 Fe0 is readily oxidized to produce H2 stoichiometrically and that CO2 is reduced catalytically over the Fe0-based composites with the resulting H2 to produce hydrocarbons and alcohols.