First-principles study of oxygen and hydrogen adsorption on Pt(111) and PtML/Pd(111) surfaces

Abstract

In this paper, first-principles calculations based on density functional theory (DFT) have been performed to investigate the adsorption of oxygen and hydrogen on [Formula: see text] and [Formula: see text] surfaces covered by monolayer (ML) of [Formula: see text]. The results have shown that the oxygen molecule tends to adsorb on fcc site on both surfaces at the coverage of 0.25 ML, which becomes degeneration with hcp site when the coverage increases to 1 ML. For both oxygen and hydrogen, the adsorption on [Formula: see text] surface are stronger than those on [Formula: see text] surface. The adsorption energy difference for oxygen on the two surfaces is [Formula: see text][Formula: see text]0.2 eV at the coverage of 1 ML, which increases to [Formula: see text][Formula: see text]0.6 eV with the coverage decreasing to 0.25 ML. The similar energy difference was also found for hydrogen adsorption. The density of states analysis have demonstrated the chemical interaction of adsorbed oxygen with both pure [Formula: see text] and [Formula: see text] surfaces with certain shift of [Formula: see text] states to lower level compared to isolated oxygen. For hydrogen adsorption, the hybridization of [Formula: see text] with [Formula: see text] states were observed for both surfaces, indicating the covalent bonding component of H–Pt bond.