Mechanochemical-Driven Uniformly Dispersed Monatomic Fe–N<sub><i>x</i></sub> Coordination in Carbon for Facilitating Efficient Oxygen Reduction Reaction
Jin Yan, Kai Zeng, Wanlu Hu, Junhua Zhou, Xin Chen, Chaohui Wei, Rafael G. Mendes, Mark H. Rümmeli, Ruizhi Yang
Abstract
The need for highly efficient and economical non-Pt electrocatalysts for facilitating the oxygen reduction reaction (ORR) has led to the development of atomically dispersed transition-metal- and nitrogen-doped carbon electrocatalysts. However, this task remains challenging due to the metal components’ easy aggregation. The present work addresses this issue by presenting a viable mechanochemical strategy for synthesizing highly dispersed monatomic Fe–Nx coordination in carbon (MFe-NC) electrocatalysts using Fe-zeolitic imidazolate framework precursors. Benefiting from the high density of Fe–Nx coordination, the as-synthesized MFe-NC catalyst exhibits remarkable electrochemical performance toward ORR with greater activity, selectivity, and durability than the commercial Pt/C electrocatalyst. Applying MFe-NC as the catalyst for a Zn–air battery cathode, a high peak power density of 302 mW cm–2 has been achieved. The specific mechanism facilitating the ORR process is unveiled by density functional theory calculations: the favoring of monatomic Fe–N4 sites for the adsorption of intermediate species during the reaction contributes mainly to the high ORR activity.