Excavating highly efficient and cost-effective non-noble metal single-atom catalysts for electrocatalytic CO₂ reduction reaction (CO₂RR) is of paramount significance. However, the general and universal strategy for designing atomically dispersed metals as accessible active sites is still in its infancy. Herein, we reported a general sol–gel pore-confined strategy for preparing a series of isolated transition metal single atoms (Fe/Co/Ni/Cu) anchored on nitrogen-doped carbon matrix. Benefiting from synergistic effect of M-N₄ coordination and neighboring N doping, the Fe-N₄-C catalyst exhibited superior capability with a Faradaic efficiency of 96.9%, achieving highly stable electrocatalytic activity for more than 20 h. Density functional theory (DFT) calculations further revealed the changes in the d_xz orbital of Fe, with a decrease in the out-of-plane component. Thus, a lower free energy barrier (ΔG) in thermodynamic pathway and the accelerated proton transfer to *COOH in kinetic pathway both enhanced electrocatalytic process.

中文翻译：

---

溶胶-凝胶孔限策略合成原子分散的金属位点以增强 CO2 电还原


挖掘高效、低成本的非贵金属单原子催化剂用于电催化CO ₂还原反应（CO ₂ RR）具有重要意义。然而，将原子分散的金属设计为可接近的活性位点的通用策略仍处于起步阶段。在此，我们报道了一种通用的溶胶-凝胶孔限策略，用于制备一系列锚定在氮掺杂碳基质上的孤立过渡金属单原子（Fe/Co/Ni/Cu）。受益于MN ₄配位和邻近N掺杂的协同效应，Fe-N ₄ -C催化剂表现出优异的性能，法拉第效率高达96.9%，实现了超过20 h的高度稳定的电催化活性。密度泛函理论（DFT）计算进一步揭示了Fe d _xz轨道的变化，面外分量减少。因此，热力学途径中较低的自由能垒（ΔG）和动力学途径中质子向*COOH的加速转移都增强了电催化过程。