Excavating highly efficient M-N-C electrocatalysts for electrochemical CO₂ reduction (ECR) is of paramount importance. Herein, we report a single-atom Co-N-C catalyst (CoN₄-CB) with a high CO Faradaic efficiency (FE_CO, 98.7%) in ECR comparable to that of a similarly prepared NiN₄-CB catalyst. Impressively, CoN₄-CB demonstrates a CO turnover frequency of 27173 h⁻¹ and a CO current density of −33.6 mA∙cm⁻² at −0.76 V, 20.2 and 6.8 times higher than that of NiN₄-CB, respectively. In a solar-driven ECR system composed of a Si solar cell and a flow cell, CoN₄-CB shows a remarkably large current density of 98.3 mA∙cm⁻² with an average FE_CO of 92.1%. Theoretical calculations suggest that the energy barrier for *COOH formation largely decreases on CoN₄ sites compared with NiN₄ sites, leading to a low onset potential and high activity for CO production. This work will boost the development of efficient M-N-C electrocatalysts and further practical application of solar-driven ECR system.

开发用于电化学 CO ₂还原 (ECR) 的高效 MNC 电催化剂至关重要。在此，我们报告了一种单原子 Co-NC 催化剂（CoN ₄ -CB），其在 ECR 中具有与类似制备的 NiN ₄ -CB 催化剂相当的高 CO 法拉第效率（FE _CO，98.7%）。令人印象深刻的是，CoN ₄ -CB在 -0.76 V 下表现出 27173 h ^-1的 CO 周转频率和 -33.6 mA∙cm ^-2的 CO 电流密度，分别比 NiN ₄ -CB高 20.2 和 6.8 倍。在由 Si 太阳能电池和流动电池组成的太阳能驱动 ECR 系统中，CoN ₄-CB 显示出非常大的电流密度，为 98.3 mA∙cm ^-2，平均 FE _CO为 92.1%。理论计算表明，对于* COOH形成能量势垒上的CoN很大程度上降低了₄位与NIN相比₄点，导致低开始电位高活性有限公司生产。这项工作将促进高效 MNC 电催化剂的开发和太阳能驱动 ECR 系统的进一步实际应用。