Improved hydrogen oxidation reaction under alkaline conditions by ruthenium–iridium alloyed nanoparticles

Abstract

Carbon supported Ru–Ir (Ru–Ir/C) catalysts with their alloyed nanoparticles and those mainly having segregated Ru and Ir nanoparticles were prepared. The Ru–Ir alloyed nanoparticles improved the hydrogen oxidation reaction (HOR) activity under alkaline conditions in comparison with the segregated Ru and Ir nanoparticles as well as Ru/C and Ir/C. Furthermore, the HOR activity of Ru–Ir alloyed nanoparticles was ca. four times higher than that of Pt/C. The cause of the enhanced HOR activity of Ru–Ir alloyed nanoparticles was investigated in terms of the hydrogen-binding energy (HBE). It was found that the HOR activity increases with a decrease of the HBE, and Ru–Ir alloying lowers the HBE in comparison with the segregated Ru–Ir nanoparticles and Ir/C. Therefore, the lowered HBE by Ru–Ir alloying was considered to be responsible for the high HOR activity of Ru–Ir alloyed nanoparticles.