Electrochemical reduction of CO2 to multi-carbon fuels and chemical feedstocks is an appealing approach to mitigate excessive CO2 emissions. However, the reported catalysts always show either a low Faradaic efficiency of the C2+ product or poor long-term stability. Herein, we report a facile and scalable anodic corrosion method to synthesize oxygen-rich ultrathin CuO nanoplate arrays, which form Cu/Cu2O heterogeneous interfaces through self-evolution during electrocatalysis. The catalyst exhibits a high C2H4 Faradaic efficiency of 84.5%, stable electrolysis for ~55 h in a flow cell using a neutral KCl electrolyte, and a full-cell ethylene energy efficiency of 27.6% at 200 mA cm−2 in a membrane electrode assembly electrolyzer. Mechanism analyses reveal that the stable nanostructures, stable Cu/Cu2O interfaces, and enhanced adsorption of the *OCCOH intermediate preserve selective and prolonged C2H4 production. The robust and scalable produced catalyst coupled with mild electrolytic conditions facilitates the practical application of electrochemical CO2 reduction.

Dual‐atom catalysts have the potential to outperform the well‐established single‐atom catalysts for the electrochemical conversion of CO2. However, the lack of understanding regarding the mechanism of this enhanced catalytic process prevents the rational design of high‐performance catalysts. Herein, an obvious synergistic effect in atomically dispersed Ni–Zn bimetal sites is observed. In situ characterization combined with density functional theory (DFT) calculations reveals that heteronuclear coordination modifies the d‐states of the metal atom, narrowing the gap between the d‐band centre (εd) of the Ni (3d) orbitals and the Fermi energy level (EF) to strengthen the electronic interaction at the reaction interface, resulting in a lower free energy barrier (ΔG) in the thermodynamic pathway and a reduced activation energy (Ea) as well as fortified metal–C bonding in the kinetic pathway. Consequently, a CO faradaic efficiency of >90% is obtained across a broad potential window from −0.5 to −1.0 V (vs RHE), reaching a maximum of 99% at −0.8 V, superior to that of the Ni/Zn single‐metal sites.

Considering increasing environmental pollution and fossil fuel depletion concerns, renewable energy technologies such as fuel cells, [1] solar cells, [2] Li-ion batteries, [3] and metal-air batteries play an important scientific research role. [4] Rechargeable metal-air batteries [5,6] have received tremendous attention owing to the potential application to replace the mature Li-ion battery, which has nearly reached its theoretical performance limits. [7] Typically, rechargeable metal-air batteries can be divided into two subgroups depending on the electrolyte: water-sensitive systems using organic electrolytes, such as Li-air batteries, which still suffer from organic electrolyte issues where insoluble solid reaction products (Li 2 O or Li 2 O 2 ) block subsequent reactions; [8] and cell systems using aqueous electrolytes, like Zn-air batteries, which are considered as safe and reliable metal-air battery systems. [6] For Designing highly active and bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) catalysts has attracted great interest toward metal-air batteries. Herein, an efficient solution to the search for MXene-based bifunctional catalysts is proposed by introducing non-noble metals such as Fe/Co/Ni at the surfaces. These results indicate that the ultrahigh activities in Ni1/Ni2-and Fe1/Ni2-modified MXene-based doubleatom catalysts (DACs) for bifunctional ORR/OER are better than those of well-known unifunctional catalysts with low overpotentials, such as Pt(111) for the ORR and IrO 2 (110) for the OER. Strain can profoundly regulate the catalytic activities of MXene-based DACs, providing a novel pathway for tunable catalytic behavior in flexible MXenes. An electrochemical model, based on density functional theory and theoretical polarization curves, is proposed to reveal the underlying mechanisms, in agreement with experimental results. Electronic structure analyses indicate that the excellent catalytic activities in the MXene-based DACs are attributed to the electroncapturing capability and synergistic interactions between Fe/Co/Ni adsorbents and MXene substrate. These findings not only reveal promising candidates for MXene-based bifunctional ORR/OER catalysts but also provide new theoretical insights into rationally designing noble-metal-free bifunctional DACs.

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