Multiple‐Active‐Site Fe/Cu‐N x Coupled with Carbon‐Coated Fe 3 O 4 Nanoparticles Enhance the Activity and Stability for Oxygen Reduction of Zn‐Air Battery Cathodes

ABSTRACT Iron‐based catalysts are the most promising oxygen reduction reaction (ORR) catalysts for accelerating the development of Zn‐air batteries (ZABs). However, their suboptimal durability stemming from insufficient active site efficiency and carbon corrosion remains a challenge that necessitates further investigation. Herein, a novel Cu‐doped Fe‐based catalyst comprising both highly distributed Fe/Cu‐N x moieties and carbon layer‐coated Fe 3 O 4 nanoparticles on nitrogen‐doped carbon (Fe 3 O 4 @NC/FeCuNC) is developed by a pyrolysis method for ORR. Besides the large specific surface area and superior hierarchical porous structure, which not only provide abundant exposed active sites but also facilitate the adsorption and desorption of reaction intermediates, Fe 3 O 4 @NC/FeCuNC also possesses a capability to significantly suppress radical accumulation coupled with high graphitization, which enables the effective inhibition of carbon corrosion to enhance its stability. Consequently, Fe 3 O 4 @NC/FeCuNC demonstrates prominent ORR efficiency, with a half‐wave potential ( E 1/2 ) of 0.898 V and exceptional stability with a tiny decline in E 1/2 after 20 000 cycles, profoundly surpassing commercial Pt/C. Moreover, the constructed Zn‐air battery reaches a peak power density of 210.6 mW cm −2 along with ultrastable operation of 1000 h, showcasing its significant practical application potential.