Electrochemical reduction of carbon dioxide (CO₂) is a potentially useful step in energy storage and greenhouse gas alleviation. Here we demonstrate for the first time a Fe-N₄O-doped nanoporous carbon as robust electrocatalyst for CO₂ reduction, where the five-coordinated Fe-N₄O structure works as catalytically active site. It exhibits a high faradaic efficiency of 96% towards CO with partial current density of -5.4 mA cm^-2 at low overpotential of 470 mV. First-principles density functional theory calculations reveal that the free energy barrier for *CO desorption is greatly reduced on Fe-N₄O site compared to Fe-N₄, resulting in a higher selectivity to CO for a wider electrochemical window. This work opens up new possibilities for improving the catalytic performance of metal-N-C electrocatalysts by regulating the co-ordination of metal atom.

电化学还原二氧化碳（CO ₂）是能量存储和温室气体减排中潜在的有用步骤。在这里，我们首次证明了Fe-N ₄ O掺杂的纳米多孔碳作为还原CO ₂的强效电催化剂，其中五配位的Fe-N ₄ O结构充当了催化活性位点。在470 mV的低过电势下，它对CO表现出96％的高法拉第效率，部分电流密度为-5.4 mA cm ^-2。第一性原理密度泛函理论计算表明，与Fe-N ₄相比，Fe-N ₄ O位上* CO解吸的自由能垒大大降低，因此对于更宽的电化学窗口，对CO的选择性更高。这项工作通过调节金属原子的配位，为改善金属-NC电催化剂的催化性能开辟了新的可能性。