Fine control on the axial ligand elements improves the oxygen reduction performance of iron phthalocyanine

Axial coordination was one of the effective strategies for modulating the electronic structure of single-atom catalysts. However, the mechanisms of different axial coordination configurations varied significantly, making it difficult to identify the optimal axial ligand. Here, iron phthalocyanine (FePc) was employed as a model catalyst and loaded onto activated carbon (AC) supports pre-anchored with different heteroatoms (O, N, C) for constructing FePc-based model catalysts with different axial ligand elements. All prepared axial coordination catalysts exhibited excellent activity for the oxygen reduction reaction (ORR), with the performance order of: O>N>C. Through the systematic comparison of these model catalysts, an evaluation of the performance differences in modulating the Fe–N₄ structure by different elements was unified. This work reveals the importance of carbonaceous support for tailoring the performance of macrocyclic molecules in electrocatalysis.