Steering the In Situ Reconstruction of Cobalt–Iron Sulfide Polyhedra‐Encaged Nanoarrays Cathode for High‐Performance Rechargeable/Flexible Zinc‐Air Batteries

ABSTRACT

Transition‐metal sulfide‐based electrocatalysts hold great promise for the advancement of various renewable energy technologies, yet their complex in situ surface reconstruction during electrochemical operation remains a significant challenge. Herein, we report a highly efficient binder‐free bifunctional electrocatalyst, FeS/CoS _1.097 @NC, consisting of cobalt‐iron sulfide polyhedra encapsulated within nitrogen‐doped carbon nanorods directly grown on carbon cloth. The judiciously designed FeS/CoS _1.097 @NC architecture features abundant active sites, moderate wettability, and reinforced electronic synergy, which collectively facilitate interfacial charge transfer and redox kinetics. As a bifunctional catalyst, FeS/CoS _1.097 @NC realizes a low overall overpotential of 0.6 V, comparable to that of the Pt/C+RuO ₂ benchmark. Combined experimental and theoretical investigation unravels that the in situ electrochemical reconstruction process promotes the formation and stabilization of Co‐Fe (oxy)hydroxides as the dominant active phase. Notably, the reconstructed hybrid phases effectively modulate the d ‐band center and optimize the binding affinity of active sites toward (oxy) intermediates, thereby enhancing both oxygen evolution reaction (OER)/oxygen reduction reaction (ORR) kinetics and long‐term durability. When employed as a free‐standing air‐cathode, FeS/CoS _1.097 @NC endows rechargeable and flexible Zn‐air batteries with high discharge capacities, superb rate capability and robust operational durability upon cycling. This work envisions a promising approach to constructing high‐efficiency hetero‐structured electrocatalysts toward multifunctional catalysis and portable/wearable energy devices.