Interface engineering of FeCo-Co structure as bifunctional oxygen electrocatalyst for rechargeable zinc-air batteries via alloying degree control strategy

High performance zinc-air batteries (ZABs) demand highly active bifunctional catalysts for both oxygen reduction reaction (ORR) and oxygen evolution reactions (OER). Herein, we report a FeCo-Co bifunctional catalyst with well-engineered interfaces between FeCo nanoalloy and metallic Co, via an alloying-degree control strategy. The FeCo-Co architecture can be obtained by manipulating the alloying degree through proper introduction of Fe, while the stacked carbon nanosheet morphology inherited from the precursor can fully expose the active sites facilitating the ion transfer. FeCo-Co interface structure enables FeCo@Co/N-C-8 catalyst to exhibit an excellent half-wave potential (0.870 V) superior to Pt/C (0.846 V) for ORR and suppressed overpotential (312 mV) than IrO 2 (321 mV) for OER. The as prepared rechargeable ZAB based on FeCo@Co/N-C-8 catalyst displays an excellent peak power density of 148 mW cm −2 and an ultrahigh open circuit voltage of 1.52 V. This research provides an innovative technique in construction of bifunctional catalysts for ZABs through alloying degree control strategies.