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

Abstract

Favorable dissociative adsorption of H₂ 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 H₂ 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 H₂ dissociation on Pt (111), Ir (111), and Pt–Ir (111). The reaction profile of H₂ dissociative adsorption on the catalysts indicated enhanced HOR on Pt–Ir (111) compared to pure Pt (111), which was attributed to more favorable H₂ 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.