Evaluation of tungsten carbide as the electrocatalyst support for platinum hydrogen evolution/oxidation catalysts

WC was investigated as an electrocatalyst support material for a monolayer-equivalent of Pt and the Pt/WC system was evaluated as an electrocatalyst for the HER and HOR and compared to commercial Pt/C. It was found that Pt/WC lost only 4% of its activity during aging, which was significantly better than Pt/C, which lost more than 20% of its activity under identical operating conditions. Most of the degradation of the Pt/WC performance was due to the decomposition of impurity WOx species on the support surface from synthesis that was identified by XPS. The activity and mechanism for the HER and HOR were also quantitatively evaluated. It was found that the reaction kinetics for the HER and HOR in both catalyst systems, Pt/WC and Pt/C, were identical, proceeding through the Volmer–Heyrovsky mechanism with an apparent activation energy of approximately 35 kJ/mol.

WC was found to be a promising electrocatalyst support material for monolayer Pt catalysts for the reversible hydrogen oxidation/evolution reaction in acid media. It was found that Pt/WC maintained high activity after potentiometric cycling, in contrast to Pt/Vulcan, which was due to excellent surface stability in the potential range of interest and strong metal-support interaction.Figure optionsDownload as PowerPoint slideHighlights
► WC is a promising electrocatalyst support material for monolayer Pt.
► Pt/WC is an effective electrocatalyst for the HER and HOR.
► Pt/WC shows significantly improved electrochemical stability in the HOR/HER potential window compared to Pt/Vulcan.
► In contrast to suggestions in the literature, WC does not enhance the intrinsic activity of Pt for either the HOR or HER.