(293f) Towards Highly Active Hydrogen Oxidation Reaction Electrocatalysts in Alkaline

Hydrogen electrodes, where the hydrogen oxidation/evolution reaction (HOR/HER) occurs, are not only the key components in energy conversion devices such as hydrogen fuel cells and water electrolyzers, but also one of the typical electrochemical reactions that have inspired the fundamental laws of electrode kinetics. The hydrogen binding energies are the generally accepted descriptor for the HOR/HER kinetics. However, significantly pH effect was found on platinum group metals (e.g., Pt, Ir, Pd and Rh), which indicated another factor determined the HOR/HER kinetics. Here, we show that the structure of the electrode-electrolyte interfacial water affects the HOR/HER kinetics as well. Ru is used as the model to study the relationship between structure of the interfacial water and HOR/HER performance, because of its unique HOR/HER pH effect. It is found that the ratio of the strongly bonded water correlates to the HOR/HER kinetics. Base on this understanding, a highly active HOR catalyst in alkaline is developed by manipulating the interfacial water structures.