Meso/Microporous Single‐Atom Catalysts Featuring Curved Fe−N ₄ Sites Boost the Oxygen Reduction Reaction Activity

Abstract Zeolitic‐imidazolate frameworks (ZIFs) are among the most efficient precursors for the synthesis of atomically dispersed Fe−N/C materials, which are promising catalysts for enhancing the performance of Zn‐air batteries (ZABs) and proton exchange fuel cells (PEMFCs). However, existing ZIF‐derived Fe−N/C electrocatalysts mostly consist of microporous materials, leading to insufficient mass transport and inadequate battery/cell performance. In this study, we synthesize an atomically dispersed meso/microporous Fe−N/C material with curved Fe−N 4 active sites, denoted as FeSA−N/TC, through the pyrolysis of hemin‐modified ZIF films on ZnO nanorods, obtained from the self‐assembly reaction between Zn 2+ from ZnO hydrolysis and 2‐methylimidazole. Density functional theory calculations demonstrate that the curved Fe−N 4 active sites can weaken the intermediate adsorptions, resulting in lower free energy barriers and enhanced performance during oxygen reduction reaction (ORR). Specifically, FeSA−N/TC exhibits exceptional ORR performance with half‐wave potentials of 0.925 V in alkaline media and 0.825 V in acidic media. When used as the cathodic catalyst in PEMFCs and ZABs, FeSA−N/TC achieves high peak power densities (H 2 −O 2 PEMFC: 1100 mW cm −2 ; H 2 −Air PEMFC: 715 mW cm −2 ; liquid‐state ZAB: 228 mW cm −2 ; solid‐state ZAB: 112 mW cm −2 ), demonstrating its feasibility and efficiency in practical applications.