Seed-mediated construction of bimetallic FeCo clusters on Ndoped mesoporous carbon for bifunctional electrocatalysis in rechargeable Zn-air batteries

Abstract

The precise synthesis of non-precious bimetallic clusters, featuring narrow size distribution and tailored electronic structures, remains a major challenge for developing high-efficiency bifunctional oxygen electrocatalysts (ORR/OER) in rechargeable zinc-air batteries (Re-ZABs). Herein, we develop a seeded-growth strategy to fabricate ultrafine FeCo bimetallic clusters anchored on nitrogen-doped spiral mesoporous carbon (FeCo/SMC), which show excellent ORR/OER performances in Re-ZABs. Initially, Co single-atom seeds are formed on SMC via ammonia-mediated pyrolysis, which subsequently direct the precise growth of FeCo clusters that are atomically intermixed and have a narrow size distribution. It is found that the FeCo/SMC exhibits a high ORR half-wave potential of 0.89 V, a low OER overpotential (η) of 379 mV at 10 mA cm-2, and a minimal potential gap (ΔE) of 0.72 V in 0.1 M KOH. In addition, Re-ZABs assembled with FeCo/SMC achieve a peak power density of 221 mW cm-2 and demonstrates remarkable long-term cycling stability exceeding 750 h. Mechanistic studies reveal that the Co single-atom seeds not only suppress cluster aggregation but also optimize the electronic structure of FeCo clusters, thereby enhancing ORR/OER performances. This work provides a facile strategy for synthesizing size-controlled bimetallic clusters, which have the potential to further enhance the efficiency and long-term durability of Re-ZABs.