The Role of Ru in Improving the Activity of Pd toward Hydrogen Evolution and Oxidation Reactions in Alkaline Solutions

Improving the reaction kinetics of hydrogen evolution and oxidation reactions (HER/HOR) in alkaline media is critical to promote the development of alkaline fuel cells and electrolyzers. Here, we prepared Pd3Ru alloy nanocatalysts with Ru segregated on the surfaces, forming adatoms and clusters. This structure dramatically lowered the overpotential of Pd toward HER in 1 M KOH by 104 mV at 10 mA cm-2. The HER activity was even higher than that of Pt (6 mV improvement at 10 mA cm-2). Theoretical simulation results revealed that Ru adatoms/clusters on the surface could weaken the hydrogen-binding energy and promote the OH adsorption, consequently lowering the reaction barrier of the rate-determining step in HER. Our findings are of significance for clarifying the role of Ru in bimetallic catalysts and rational design of more active catalysts for HER/HOR.