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

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…

• NN
  National Natural Science Foundation of China

  Awards: 51772332, 51972345
• CP
  China Postdoctoral Science Foundation

  Award: 2021M691876
• NS
  Natural Science Foundation of Hunan Province

  Award: 2021JJ30790