Alternative Cu3Zn catalysts for enhanced reduction of CO2 to CH4: A density functional theory-based approach

Abstract

The synthesis of syngas is considered to be an important area of research in the context of the energy crisis arising from the depletion of fossil fuels. CH4 is a highly potent greenhouse gas; however, it is also a renewable energy source of significant importance. CH4 can be generated via the electrochemical CO2 reduction reaction (CO2RR). Various heterogeneous and homogeneous metallic catalysts with optimal activities have been developed based on the pure Cu catalyst for enhancing reactivity for the CO2RR. However, Cu catalysts suffer from an unresolved issue involving a high overpotential for the CO2RR. Therefore, Cu3M alloy catalyst systems (M = 3d transition metals) were investigated herein for increasing the reactivity for the CO2RR. The relative adsorption strength between CO and CHO on the Cu3M surface was targeted based on the fact that the reaction step involving these species is possibly the potential-limiting step in the CO2RR. Cu3Zn was revealed to be a catalyst with tremendous potential for the reduction of CO2 to CH4. The energetic and electronic structural changes of the intermediate adsorbed state were analyzed using density functional theory, and the obtained results were used to design an effective catalyst for CH4 production via the CO2RR.