Alleviating the activity trade-off in oxygen reactions with sulfur-modulated iron‑cobalt bimetallic catalysts for high-performance zinc-air batteries

With the rapid development of renewable energy and the increasing demand for high-efficiency energy storage technologies, the development of high-performance electrocatalysts has become critically important. However, the intrinsic trade-off between the catalytic activities of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) remains a major challenge limiting the performance of bifunctional electrocatalysts. Herein, a sulfur-modulated FeCo bimetallic catalyst (FeCoS-NC@CNT) was constructed via a synergistic strategy combining heteroatom-induced electronic regulation and carbon nanotube confinement, aiming to achieve coordinated optimization of bifunctional ORR/OER catalytic performance. As a result, the catalyst exhibits excellent bifunctional performance, delivering a high ORR half-wave potential (0.904 V), a low OER overpotential (320 mV at 10 mA cm −2 ), and a small potential gap (ΔE = 0.646 V). Applied in a zinc–air battery, it achieves an open-circuit voltage of 1.507 V, a high peak power density of 164.33 mW cm −2 , a specific capacity of 813.37 mAh g Zn −1 , and outstanding stability up to 900 h. This work provides an effective strategy for alleviating the ORR/OER trade-off and offers useful insights into the development of high-performance electrocatalysts for advanced energy storage systems, particularly rechargeable zinc–air batteries.