Model of the CO oxidation reaction on Au-covered Mo(112)

Abstract

The adsorption of O and CO and the CO oxidation reaction on the Au-covered Mo(112) surface have been studied by means of DFT calculations of binding and activation energies. As follows from previous studies [K. Fukutani et al., Appl. Surf. Sci. 256, (2010) 4796], adsorbed Au atoms create rods lying in the furrows of the Mo(112) surface. Due to a furrowed structure of the Mo(112), a p(1 × 1)Au monolayer does not cover the surface completely, and Mo atomic rows remain available for oxygen adsorption. It is found that oxygen adsorbs dissociatively on these Mo substrate atoms. In turn, CO molecules prefer adsorption sites on the Au rows atop Au atoms, so that CO and oxygen do not hinder each other from adsorption. The Au coating significantly decreases the binding energy of O on the Mo(112) surface. This feature is essential for the lowering of the barrier for CO oxidation, which is found to be as low as 0.19 eV. In presence of adsorbed O, the binding energy of CO is relatively small (0.29 eV), but increases to 0.64 eV when CO adsorbs on bilayer Au films. Hence, the p(1 × 4) and p(1 × 3) Au bilayer structures on Mo(112) surface are predicted to be efficient catalysts for CO oxidation.