Asymmetrical FeN ₄ ‐O‐FeO ₄ Dual‐Atom Sites in Fe─N─C for Robust pH‐Universal Oxygen Reduction Reaction Catalysis

ABSTRACT M‐N‐C single‐atom catalysts have been demonstrated to be a promising class of non‐noble‐metal based catalysts, but their activity is largely constrained by the symmetrical electronic density distribution of the M‐N ₄ moieties. Herein, a ZIF‐8 derived Fe/Fe dual‐center catalyst (FeN ₄ /FeO ₅ @NC) is constructed by introducing a O‐FeO ₄ configuration adjacent to the Fe‐N ₄ sites to form asymmetric dumbbell‐shaped FeN ₄ ‐O‐FeO ₄ active sites, resulting in improved intrinsic activity of Fe─N─C catalyst. The dumbbell FeN ₄ ‐O‐FeO ₄ dual‐center catalyst features an electron transfer pathway of “FeN ₄ → bridged O → FeO ₄ ”, which breaks the symmetry of the electronic density distribution of the Fe moiety and regulates the position of the d‐band center, increasing the electron transfer efficiency, reducing the desorption energy barrier of the rate‐determining step, and enhancing the activation ability of O ₂ molecules. The obtained FeN ₄ ‐O‐FeO ₄ dual‐center catalyst exhibits excellent ORR performance in a pH‐universal range. The liquid‐state Zn‐air battery (ZAB) with this FeN ₄ ‐O‐FeO ₄ dual‐center catalyst delivers an outstanding open circuit voltage of 1.502 V and a peak power density of 246 mW cm ⁻² , superior to the Pt/C‐cathode ZAB. This work represents an exploration of ways to improve the ORR performance of Fe─N─C catalysts and provides a paradigm for rationally designing low‐cost, highly catalytic, and stable non‐noble metal catalysts.