Effects of platinum nanoparticle shape on mass transport performance of porous carbon catalysts in fuel cells

Interfacial mass transport critically limits the performance of proton exchange membrane fuel cells at low platinum loadings. Although adsorption resistance at the ionomer and platinum interface has been identified as a major source of local transport limitation, the influence of platinum nanoparticle shape on interfacial transport behavior under water film coverage remains unclear. In this work, oxygen and proton transport on platinum nanoparticles covered by water films are investigated using atomistic simulations under an identical chemical environment. The results show that oxygen does not penetrate uniformly across the surface but preferentially migrates along regions with low atomic coordination, and nanoparticles with a higher proportion of edges exhibit lower interfacial resistance and more continuous transport pathways. In contrast, facet dominated structures maintain a more compact interfacial layer that hinders oxygen accessibility. Meanwhile, shape induced reconstruction of interfacial water networks modifies proton migration pathways and alters the relative contributions of structural and vehicular mechanisms. These findings establish a direct correlation between interfacial structure and transport behavior at aqueous platinum interfaces.