Mechanochemical-Driven Uniformly Dispersed Monatomic\nFe–N_<i>x</i> Coordination in Carbon for\nFacilitating Efficient Oxygen Reduction Reaction

Abstract

The\nneed for highly efficient and economical non-Pt electrocatalysts\nfor facilitating the oxygen reduction reaction (ORR) has led to the\ndevelopment of atomically dispersed transition-metal- and nitrogen-doped\ncarbon electrocatalysts. However, this task remains challenging due\nto the metal components’ easy aggregation. The present work\naddresses this issue by presenting a viable mechanochemical strategy\nfor synthesizing highly dispersed monatomic Fe–N_<i>x</i> coordination in carbon (MFe-NC) electrocatalysts\nusing Fe-zeolitic imidazolate framework precursors. Benefiting from\nthe high density of Fe–N_<i>x</i> coordination,\nthe as-synthesized MFe-NC catalyst exhibits remarkable electrochemical\nperformance toward ORR with greater activity, selectivity, and durability\nthan the commercial Pt/C electrocatalyst. Applying MFe-NC as the catalyst\nfor a Zn–air battery cathode, a high peak power density of\n302 mW cm^–2 has been achieved. The specific mechanism\nfacilitating the ORR process is unveiled by density functional theory\ncalculations: the favoring of monatomic Fe–N₄ sites\nfor the adsorption of intermediate species during the reaction contributes\nmainly to the high ORR activity.