Enhancement of hydrogen evolution activity on Pt-skin/Pt3Co [(111), (100), and (110)] single crystal electrodes

Abstract

We have examined for the first time the hydrogen evolution reaction (HER) activity at the (111), (100), and (110) faces of well-defined Pt-skin/Pt3Co single crystal electrodes in H2-saturated 0.1 M HClO4 solution in order to clarify the mechanism for the increased HER activities at Pt-skin/Pt-M (M = Co, Fe) nanoparticles dispersed on a carbon support, which we recently developed as highly active cathode catalysts for proton exchange membrane electrolyte water electrolysis. The HER current densities at −0.02 V vs. RHE for the Pt-skin/Pt3Co single crystal rotating disk electrodes increased in the order (100) < (111) < (110), which is identical with that reported for pure Pt single crystal electrodes. Based on density functional theory calculations, the increase in the HER activity is ascribed to the destabilization of the on-top form of adsorbed atomic hydrogen (HOPD), which facilitates the recombination and desorption of two HOPD atoms to produce molecular H2. Keywords: Pt-Co alloy, Single-crystal, Hydrogen evolution reaction, Water electrolysis, Electrocatalysis