(682e) Grain Boundary-Derived Cu+/Cu0 Interfaces in CuO Nanosheets for Low Overpotential Carbon Dioxide Electroreduction to Ethylene

Electrochemical CO₂ reduction reaction holds great promises to produce value-added hydrocarbon fuels and chemicals by coupling with clean electrical energy. However, highly active and selective yet energy-efficient CO₂ conversion to multi-carbon hydrocarbons such as C₂H₄ remains challenging due to the lack of efficient catalysts. Here we report an ultrasonication-assisted electrodeposition strategy to synthesize CuO nanosheets for low overpotential CO₂ electroreduction to C₂H₄. A high C₂H₄ Faradaic efficiency of 62.5% is achieved over CuO nanosheets at a small potential of -0.52 V versus a reversible hydrogen electrode, corresponding to a record high half-cell cathodic energy efficiency of 41%. The selectivity towards C₂H₄ was maintained over 60-hour continuous operation. CuO nanosheets are prone to in-situ restructuring during CO₂ reduction, leading to abundant grain boundaries (GBs) formation. Stable Cu⁺/Cu⁰ interfaces are derived from the low-coordinated Cu atoms in the reconstructed GB regions and act as highly active sites for CO₂ reduction at low overpotentials. The in-situ Raman spectroscopic analysis and density functional theory computation reveal that Cu⁺/Cu⁰ interfaces offer high *CO surface coverage and lower the activation energy barrier of *CO dimerization, which in synergy facilitates CO₂ reduction towards C₂H₄ at low overpotentials.