Asymmetric Coordination of Bimetallic Fe–Co Single-Atom Pairs toward Enhanced Bifunctional Activity for Rechargeable Zinc–Air Batteries
Zhitong Li, Xiongwei Zhong, Leyi Gao, Junjie Hu, Wenbo Peng, Xingzhu Wang, Guangmin Zhou, Baomin Xu
Abstract
The advancement of rechargeable zinc–air batteries (RZABs) faces challenges from the pronounced polarization and sluggish kinetics of oxygen reduction and evolution reactions (ORR and OER). Single-atom catalysts offer an effective solution, yet their insufficient or singular catalytic activity hinders their development. In this work, a dual single-atom catalyst, FeCo-SAs, was fabricated, featuring atomically dispersed N 3 –Fe–Co–N 4 sites on N-doped graphene nanosheets for bifunctional activity. Introducing Co into Fe single-atoms and secondary pyrolysis altered Fe coordination with N, creating an asymmetric environment that promoted charge transfer and increased the density of states near the Fermi level. This catalyst achieved a narrow potential gap of 0.616 V, with a half-wave potential of 0.884 V for ORR (vs the reversible hydrogen electrode) and a low OER overpotential of 270 mV at 10 mA cm –2 . Owing to the superior activity of FeCo-SAs, RZABs exhibited a peak power density of 203.36 mW cm –2 and an extended cycle life of over 550 h, exceeding the commercial Pt/C + IrO 2 catalyst. Furthermore, flexible RZABs with FeCo-SAs demonstrated the promising future of bimetallic pairs in wearable energy storage devices.