Enhanced H2 dissociative phenomena of Pt–Ir electrocatalysts for PEMFCs: an integrated experimental and theoretical study

Abstract

Favorable dissociative adsorption of H-2 on electrocatalysts is a key requirement of the anode in a proton exchange membrane fuel cell (PEMFC). To enhance the electrocatalytic activity of the anode, we investigated the characteristics of the hydrogen oxidation reaction (HOR) on bimetallic nanoparticles of Pt-Ir over a carbon support. The nanoparticle Pt-Ir/C catalysts improved the HOR, owing to strong H-2 dissociation and ready formation of H+ atoms. In addition, we investigated the adsorption configuration and electronic band-gaps of the optimized structure using density functional theory calculations, to gain insight into the mechanisms and characteristics of H-2 dissociation on Pt (111), Ir (111), and Pt-Ir (111). The reaction profile of H-2 dissociative adsorption on the catalysts indicated enhanced HOR on Pt-Ir (111) compared to pure Pt (111), which was attributed to more favorable H-2 dissociation in the former, owing to a reduced electronic band-gap. The integrated experimental and theoretical study suggests that Pt-Ir/C is a potential candidate for preserving the high performance of an anodic electrocatalyst in PEMFCs.