Regulated Coordination Environment of Ni Single Atom Catalyst toward High-efficiency Oxygen Electrocatalysis for Rechargeable Zinc-air Batteries

Abstract Single atom catalysts (SACs) are emerging as a highly promising catalyst category in oxygen electrocatalysis; however, their real-world implementation in rechargeable zinc-air batteries (ZABs) is restricted by the insufficient bifunctional activity. Here, a secondary single-atom regulation strategy is developed to tailor the coordination environment and thus modify the catalytic behaviors of single atom Ni catalysts. Through introducing atomically dispersed Fe moieties, the coordination environment of single Ni atom is well regulated with a higher Ni-N/O coordination number due to the long-range electronic penetration interaction, which triggers more optimized adsorption strength between active sites and reaction intermediates. As a result, the obtained Fe, Ni dual atom catalyst (FeNi-SAs@NC) requires only 298 mV overpotential to deliver 10 mA cm−2 in oxygen evolution reaction (OER) catalysis outperforming the benchmarking IrO2 (313 mV), Fe-SAs@NC (335 mV) and Ni-SAs@NC (356 mV) electrocatalysts. Moreover, FeNi-SAs@NC performs superior oxygen reduction reaction (ORR) activity to the single-atom counterparts and Pt/C benchmark. The practical application of the FeNi-SAs@NC is further validated by a higher ZAB performance (260 mW cm−2 vs 71 mW cm−2 for Pt/C-IrO2), improved long-term durability (100 h at 20 mA cm−2) and encouraging performance in all-solid-sate ZABs (70 mW cm−2).