Insight into the Mechanism of Axial Ligands Regulating the Catalytic Activity of Fe–N 4 Sites for Oxygen Reduction Reaction

作者：Kuangmin Zhao, Suqin Liu, Yu‐Yang Li, Xianli Wei, Guanying Ye, Weiwei Zhu, Yuke Su, Jue Wang, Hongtao Liu, Zhen He, Zhi‐You Zhou, Shi‐Gang Sun · 发表于：Advanced Energy Materials · 年份：2022 · DOI：10.1002/aenm.202103588 · 被引用次数：280 · 研究领域：Electrocatalysts for Energy Conversion、Fuel Cells and Related Materials、Advanced battery technologies research

Abstract Identifying the actual structure and tuning the catalytic activity of Fe–N 4 ‐based moieties, well‐recognized high‐activity sites in the oxygen reduction reaction (ORR) are challenging problems. Herein, by using poly(iron phthalocyanine) (PFePc) as an Fe–N 4 ‐based model electrocatalyst, a mechanistic insight into the effect of axial ligands on the ORR catalytic activity of Fe–N 4 is provided and it is revealed that the ORR activity of Fe–N 4 sites with OH desorption as a rate‐determining step is related to the energy level gap between the OH p x p y and Fe 3, which can be tuned by regulating the field strength of the axial ligands. Thus, PFePc coordinated with a weak‐field ligand I − (PFePc‐I) with a low energy level of Fe 3 exhibits high activity evidenced by an ORR half‐wave potential as high as 0.948 V versus RHE. This work develops a novel strategy for tuning the ORR activity of Fe–N 4 and reveals the correlation between the electronic/geometric structure and catalytic activity of Fe–N 4 .