Molecular interface engineering of Pt/C with 14-membered rings for enhanced durability in proton exchange membrane fuel cells

The limited durability of Pt-based catalysts in the oxygen reduction reaction (ORR) is a critical challenge for proton exchange membrane fuel cells (PEMFCs). Here, we report a hexaaza macrocyclic ligand (H 2 HAM) as a novel surface modifier for commercial Pt/C catalysts. X-ray photoelectron spectroscopy (XPS) analyses (N 1s and Pt 4f ) indicate significant electron donation from H 2 HAM to the Pt surface, suggesting a strong ligand–metal interaction. Using 0.1 mM H 2 HAM as the loading condition, the H 2 HAM-modified Pt/C shows slightly improved electrochemical surface area (ECSA), mass activity (MA), and specific activity (SA) under single-cell membrane electrode assembly (MEA) test conditions compared with commercial TEC10E50E. More importantly, durability tests reveal that the modified catalyst retains 90% of its initial performance after 36,300 cycles, nearly twice that of TEC10E50E (18,400 cycles). This study demonstrates that macrocyclic ligand modification is a promising strategy to enhance both the activity and long-term stability of Pt-based ORR catalysts for PEMFC applications. • Hexaaza macrocyclic ligand modifies Pt/C via strong metal–ligand interaction. • Electronic modulation of Pt improves ORR activity under MEA conditions. • Durability significantly enhanced with 1.7 × longer lifetime. • Ligand layer suppresses Pt nanoparticle agglomeration during cycling.