Metal-mediated Schiff base polymer enables metal/nitrogen codoped carbon nanosheets as efficient bifunctional electrocatalyst for durable rechargeable Zn-air batteries

We report a simple yet robust route to bifunctional electrocatalysts comprising FeNi and Co4N hybrid nanoparticles co-embedded within N-doped carbon nanosheets (denoted FeNi/Co4N-NCS) for rechargeable Zn-air batteries (ZABs) with high power density and capacity as well as outstanding cycling stability, markedly outperforming the Pt/C&IrO2 electrocatalyst counterpart. The as-crafted FeNi/Co4N-NCS electrocatalysts display outstanding bifunctional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activity with a low overall oxygen electrode activity (ΔE = 0.664 V). Density functional theory (DFT) calculations reveal that the synergy of FeNi and Co4N reduces the rate-determining step (RDS) energy barrier, thereby greatly increasing electrocatalytic activity. The aqueous ZAB assembled with FeNi/Co4N-NCS delivers a high power density of 160 mW cm−2, large specific capacity of 812 mAh g−1Zn, and long cycling life of 1450 h at 5 mA cm−2. This study highlights an effective strategy to yield durable bifunctional electrocatalysts for metal-air batteries.