Meso/Microporous Single‐Atom Catalysts Featuring Curved Fe−N <sub>4</sub> Sites Boost the Oxygen Reduction Reaction Activity
Ying Yu, Yian Wang, Fei Yang, Dong Feng, Mingyang Yang, Pengfei Xie, Yuanzhi Zhu, Minhua Shao, Yi Mei, Jincheng Li
Abstract
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.