In-situ SERS Reveals Nickel Hydroxide Formation in PtRuNi Catalysts Enhancing Hydrogen Oxidation

Abstract

Understanding the mechanisms for improving hydrogen oxidation reaction (HOR) activity on Pt-based catalysts in alkaline environment is challenging due to the lack of directly observed intermediates. Understanding the role of oxophilic metal additives is also crucial for designing advanced catalysts. In this study, we use in situ surface-enhanced Raman spectroscopy (SERS) to investigate HOR on Au@PtRuNi nanoparticles. Electrochemical measurements show improved HOR activity with little change in hydrogen binding energy (HBE), whereas Raman results show the 740 cm-1 peak for hydroxyl adsorption on Ru, as well as a new peak at 565 cm-1, which can likely be attributed to the formation of nickel hydroxide (Ni(OH)2) during the catalytic process, starting from 0.3 to 0.5V vs RHE. This suggests that nickel hydroxide and the hydroxyl groups on ruthenium likely collaborate to facilitate hydrogen oxidation.