Anion exchange membrane fuel cells (AEMFCs) are being developed for practical use. However, it is necessary to improve the hydrogen oxidation reaction (HOR) under alkaline conditions to enhance the performance of AEMFCs. In this study, carbon-supported Ru-Ir alloy nanoparticle catalysts (Ru-Ir/C) were developed because they offer higher HOR activity compared with the Pt-based catalysts. The mechanism of HOR enhancement on Ru-Ir/C was studied to reveal the effect of the surface composition of Ru/Ir on the HOR activity. The results showed that the HOR activity is related to the surface pair probability of Ru-Ir, Ru-Ru, and Ir-Ir but not to the hydrogen binding energy (HBE). In addition, the Ru-Ir pair site was found to be highly active, which can promote the HOR through a bifunctional mechanism that involves Ru-Ir pairs providing reactive OH- and H species, respectively.
Keywords: Ru−Ir; alloy; anion exchange membrane fuel cells; bifunctional mechanism; hydrogen oxidation reaction.