On the enhanced electrocatalytic activity of Pd overlayers on carbon-supported gold particles in hydrogen electrooxidation

Abstract

Palladium-gold particles with varied composition were prepared by Pd electrochemical deposition on Au nanoparticles immobilized on model carbon support. Pd–Au/C catalysts were characterized ex situ by transmission electron microscopy, energy dispersive X-ray analysis and X-ray photoelectron spectroscopy, and in situ, by underpotential deposition of hydrogen and copper adatoms, and CO stripping. Hydrogen oxidation reaction on pristine and CO-poisoned Pd–Au/C particles was studied using rotating disk electrode (RDE) technique. It was found that the decrease of the effective Pd overlayer thickness below ca. two monolayers resulted in a two-fold increase of the exchange current density of the hydrogen oxidation reaction and in significant increase of CO tolerance.