Metal-N-C is a type of attractive electrocatalyst for efficient CO2 reduction to CO. Because of the ambiguity in their atomic structures, the active sites and catalytic mechanisms of the catalysts have remained under debate. Here, the effects of N and C hybrid coordination on the activity of Ni-N-C catalysts were investigated, combining theoretical and experimental methods. The theoretical calculations revealed that N and C hybrid coordination greatly enhanced the capability of single-atom Ni active sites to provide electrons to reactant molecules and strengthens the bonding of Ni to N and C in the Ni-N-C complexes. During the reaction process, the C and N coordination synergistically optimized the reaction energies in the conversion of CO2 to CO. A good agreement between theoretical calculations and electrochemical experiments was achieved based on the newly developed Ni-N-C electrocatalysts. The activity of hybrid-coordination NiN2 C2 was more than double that of single-coordination NiN4 .

中文翻译：

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通过混合配位优化Ni-NC配合物的电子密度，以有效地电催化还原CO2。

金属-NC是一种有效将CO2还原为CO的有吸引力的电催化剂。由于它们的原子结构含糊不清，因此催化剂的活性位点和催化机理一直处于争论之中。在这里，结合理论和实验方法，研究了氮和碳杂化配位对Ni-NC催化剂活性的影响。理论计算表明，N和C杂化配位大大增强了单原子Ni活性位向反应物分子提供电子的能力，并增强了Ni-NC络合物中Ni与N和C的键合。在反应过程中，C和N配位协同优化了从CO2转化为CO时的反应能。基于新开发的Ni-NC电催化剂，理论计算与电化学实验之间取得了良好的一致性。混合配位NiN2 C2的活性是单配位NiN4的两倍以上。