Modulating Electronic Structure of Atomic Iron Catalyst by Metallic Cobalt Cooperation for Boosting Oxygen Reduction/Evolution Reactions in Rechargeable and Flexible Zinc‐Air Battery

ABSTRACT Modulating the electronic structure of iron‐based catalysts to optimize the adsorption strength of oxygen‐containing intermediates on Fe d orbital is of great significance for addressing sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics, but there are still significant challenges. Herein, porous metal@nitrogen‐doped carbon nanofibers (defined as Co,Fe@NCNF‐900) are innovatively designed and synthesized as enhanced bifunctional catalysts ( ∆E = 0.72 V) by modulating the electronic structure of the atomic Fe catalyst through metallic Co cooperation. Density functional theory (DFT) analysis indicates that metallic Co as an electron donor can induce electron redistribution and modulate the electronic structure (negative shift d‐band center) of atomic Fe catalyst, thereby significantly reducing the rate‐determining step energy barriers of OH* and OOH* in ORR and OER. Importantly, the self‐assembled liquid zinc‐air battery (ZAB) can achieve a high peak power density (393 mW cm −2 ) and a large specific capacity (736 mAh g Zn −1 ). The study provides in‐depth insights to optimize the electronic structure of the atomic Fe catalyst and boost the bifunctional electrocatalytic activity by introducing a second metal source.