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

Abstract

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.