Grain Boundary‐Derived Cu(+)/Cu(0) Interfaces in CuO Nanosheets for Low Overpotential Carbon Dioxide Electroreduction to Ethylene

Electrochemical CO(2) reduction reaction can be used to produce value‐added hydrocarbon fuels and chemicals by coupling with clean electrical energy. However, highly active, selective, and energy‐efficient CO(2) conversion to multicarbon hydrocarbons, such as C(2)H(4), remains challenging because of the lack of efficient catalysts. Herein, an ultrasonication‐assisted electrodeposition strategy to synthesize CuO nanosheets for low‐overpotential CO(2) electroreduction to C(2)H(4) is reported. A high C(2)H(4) Faradaic efficiency of 62.5% is achieved over the 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 toward C(2)H(4) is maintained for over 60 h of continuous operation. The CuO nanosheets are prone to in situ restructuring during CO(2) reduction, forming abundant grain boundaries (GBs). Stable Cu(+)/Cu(0) interfaces are derived from the low‐coordinated Cu atoms in the reconstructed GB regions and act as highly active sites for CO(2) reduction at low overpotentials. In situ Raman spectroscopic analysis and density functional theory computation reveal that the Cu(+)/Cu(0) interfaces offer high *CO surface coverage and lower the activation energy barrier for *CO dimerization, which, in synergy, facilitates CO(2) reduction to C(2)H(4) at low overpotentials.