Composing atomic transition metal sites for high-performance bifunctional oxygen electrocatalysis in rechargeable zinc-air batteries

Rechargeable zinc-air batteries have attracted extensive attention as clean, safe, and high-efficient en-ergy storage devices. However, the oxygen redox reactions at cathode are highly sluggish in kinetics and severely limit the actual battery performance. Atomic transition metal sites demonstrate high electro-catalytic activity towards respective oxygen reduction and evolution, while high bifunctional electro-catalytic activity is seldomly achieved. Herein a strategy of composing atomic transition metal sites is proposed to fabricate high active bifunctional oxygen electrocatalysts and high-performance recharge-able zinc-air batteries. Concretely, atomic Fe and Ni sites are composed based on their respective high electrocatalytic activity on oxygen reduction and evolution. The composite electrocatalyst demonstrates high bifunctional electrocatalytic activity (DE = 0.72 V) and exceeds noble-metal-based Pt/C + Ir/C (DE = 0.79 V). Accordingly, rechargeable zinc-air batteries with the composite electrocatalyst realize over 100 stable cycles at 25 mA cm-2. This work affords an effective strategy to fabricate bifunctional oxygen electrocatalysts for high-performance rechargeable zinc-air batteries. (c) 2022 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).