Atomically dispersed Co-N-C materials represent the promising alternatives to precious metal-based catalysts for oxygen reduction reactions (ORR), due to the abundance and low cost of their constituent elements with maximized atom utilization. However, boosting their performances by modulating the active site structure still remains a challenge. Herein we have reported a pyrolysis-free synthetic method to prepare a new ORR catalyst with Co-N₅ active sites by using nitrogen-functionalized reduced graphene oxide to anchor Co-Porphyrin molecules and provide the axial ligand for the cobalt center. The ORR half-wave potential of the obtained catalyst reached 0.908 V, and the maximum power density was significantly increased by 1.63 times compared with the catalyst with traditional Co-N₄ active sites in alkaline polymer electrolyte fuel cells (APEFCs). Combined with density functional theory (DFT) calculations and electrochemical analysis, the results show that the electronic and geometric structure are remarkably changed after the Co 3d orbitals are rehybridized with the axially coordinated ligand orbitals, which greatly increases the rate of ORR. Importantly, in-situ Raman spectroscopy can dynamically track the conversion of Co-OH and Co-O species, further revealing that Co-N₅ is the active site and electron localization strategy induced by axial Co-N coordination can enhance the O₂ adsorption and activation, thus boosting ORR performance. Therefore, our research provides an atomic-level insight into the relationship between the electronic structure of the active center and the ORR performance and guidance for the rational design of high-efficiency electrocatalysts.

原子分散的 Co-NC 材料代表了用于氧还原反应 (ORR) 的贵金属基催化剂的有希望的替代品，因为它们的组成元素丰富且成本低，并且具有最大化的原子利用率。然而，通过调节活性位点结构来提高它们的性能仍然是一个挑战。在此，我们报道了一种无热解合成方法，通过使用氮功能化还原氧化石墨烯锚定Co-卟啉分子并为钴中心提供轴向配体，制备具有Co-N _{5活性位点的新型ORR催化剂。}所得催化剂的ORR半波电位达到0.908 V，与传统Co-N _{4催化剂相比，最大功率密度显着提高了1.63倍}碱性聚合物电解质燃料电池（APEFCs）中的活性位点。结合密度泛函理论（DFT）计算和电化学分析，结果表明，Co 3d轨道与轴向配位配体轨道再杂化后，电子结构和几何结构发生了显着变化，大大提高了ORR率。重要的是，原位拉曼光谱可以动态跟踪 Co-OH 和 Co-O 物种的转化，进一步揭示 Co-N ₅是活性位点，由轴向 Co-N 配位诱导的电子定位策略可以增强 O ₂吸附和活化，从而提高 ORR 性能。因此，我们的研究为活性中心的电子结构与ORR性能之间的关系提供了原子级的洞察力，并为高效电催化剂的合理设计提供了指导。