Tailoring Surface Hydrophobicity of Fe–N–C Catalysts via Fluorine Substitution in Aniline Precursors for Improved AEMFC Performance

The development of cost‐effective nonprecious metal catalysts (NPMCs) is essential for the commercialization of anion exchange membrane fuel cells (AEMFCs), particularly Fe–N–C catalysts. In Fe‐based single‐atom catalysts (Fe SACs), low Fe content often requires high catalyst loading, resulting in thick cathode catalyst layers that hinder gas diffusion, cause flooding, and degrade performance. Here, fluorine is incorporated into Fe–N–C catalysts using fluorinated aniline precursors (2‐, 3‐, 4‐fluoroaniline, abbreviated as F‐AN), while preserving single‐atom Fe–N coordination. Fluorine doping enhances local hydrophobicity, facilitating fuel transport and water removal in AEMFC operation. Among the catalysts, Fe/2‐F AN/CB catalyst derived from 2‐fluoroaniline shows no performance loss compared to non‐fluorinated Fe/AN/CB and achieves a peak power density of 207 mW/cm 2 , approaching commercial Pt/C (216 mW/cm 2 ). Subtle variations in the fluorine substitution position on the aniline precursor also significantly influence FeN x active site and catalytic activity. These findings highlight the critical role of precursor structure on active‐site formation and demonstrate how minor modifications can induce substantial improvements in AEMFC performance.