Interface Engineering of Silver-Based Heterostructures for CO₂ Reduction Reaction

The production of CO from the CO₂ reduction reaction (CO₂RR) is of great interest in the renewable energy storage and conversion, the neutral carbon emission, and carbon recycle utilization. Silver (Ag) is one of the catalytic metals that are active for electrochemical CO₂ reduction into CO, but the catalysis requires a large overpotential to achieve higher selectivity. Constructing a metal-oxide interface could be an effective strategy to boost both activity and selectivity of the catalysis. Herein, density functional theory (DFT) calculations were first conducted to reveal the chemical insights of the catalytic performance on the interface between metal oxide and Ag(111) (MO/Ag(111)). The results show that the *COOH intermediates can be more stabilized on the surfaces of MO/Ag(111) than pure Ag(111). The hydrogen evolution reaction on MO/Ag(111) can be suppressed due to the significantly higher Gibbs free energy for hydrogen adsorption (ΔG_H*), thereby enhancing the selectivity toward CO₂RR. A series of MO/Ag composites with the unique interface based on the DFT results were then introduced though a two-step approach. The as-obtained MO/Ag catalysts boosted both the CO activity and selectivity at a relatively positive potential range, especially in the case of MnO₂/Ag. The reduction current density on the MnO₂/Ag catalyst can reach 4.3 mA cm^-2 at -0.7 V (vs RHE), which is 21.5 times higher than that on pure Ag, and the overpotential of CO₂ to CO (390 mV) possesses is much lower than that on pure Ag NPs (690 mV). This study proposes an effective design strategy to construct a metal-oxide interface for CO₂RR based on the synergistic effect between metals and MO.