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

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.