Carbon Monoxide Oxidation over Au/Pd(100) Model Alloy Catalysts

Abstract

The oxidation of carbon monoxide is studied on a series of Au/Pd(100) alloys with various compositions that are formed by adsorbing four monolayers of gold onto a Pd(100) surface and by heating to form the alloy. The composition of the alloy surface is measured using Auger and low-energy ion scattering spectroscopies and the surface chemistry followed by temperature-programmed desorption and reflection absorption infrared spectroscopy. Carbon monoxide oxidized rapidly on Au/Pd(100) model alloy surfaces. Oxygen is found to dissociatively adsorb on alloy surfaces for gold coverages below ∼0.6 ML and relatively stable molecular oxygen species were found on the surface at gold coverages between ∼0.2 and 0.6 ML, but did not contribute to CO oxidation on these Au/Pd(100) alloys. Carbon monoxide oxidation and desorption were found to occur at almost identical temperatures, implying that the activation energies for these processes are almost identical. This suggests that the activation energy for CO oxidation is ...