Recent Advances in Fe‐Free M–N–C Catalysts for Oxygen Reduction Reaction
Yuxian Duan, Min Chen, Chongtai Wang, Li‐Zhi Gao, Hongxian Luo, Yichi Guan, Yu Zhou, Junming Luo, Ruisong Li, Daoxiong Wu, Xinlong Tian, Zhengpei Miao
Abstract
Atomically dispersed metal-nitrogen-carbon (M-N-C) materials, characterized by well-defined coordination structures, have emerged as promising candidates to supersede costly platinum-based catalysts for the oxygen reduction reaction (ORR). Although Fe-N-C catalysts exhibit the highest ORR activity among Pt-free systems, their practical application is hindered by durability challenges stemming from Fenton reaction-induced degradation. Fe-free M-N-C catalysts (MCo, Mn, Ni, etc.), which mitigate Fenton reactivity, have attracted significant attention; however, their catalytic activities remain markedly lower than those of Fe-based counterparts. Critical uncertainties persist in establishing structure-activity-stability relationships, particularly regarding the interplay between coordination architecture engineering, single-atom site density, and overall catalytic performance. This review critically examines ORR mechanisms underpinning M-N-C systems, evaluates innovative strategies to decouple activity and stability in Fe-free catalysts, and proposes frameworks to translate atomic-scale materials into enhanced device-level performance. Finally, a multidisciplinary roadmap integrating advanced synthesis, operando diagnostics, and machine learning to speed up the development of durable, high-performance ORR electrocatalysts is proposed.