Surface coverage effect on ammonia oxidation over Pt(211)

Abstract

The effect of surface coverage (θ) on binding energies of single NO⁎, N⁎ and O⁎ and double NO⁎-(N⁎−Pt), NO⁎−(O⁎-Pt), N⁎-(O⁎−Pt) and O⁎-(N⁎−Pt) co-adsorbed systems on Pt(211) stepped surface is elucidated for the first time by using periodic density functional theory (DFT). The effect of the surface coverage on the activation energies of elementary reactions important in ammonia oxidation is revealed at θ values of 1/12 and 1/6 mL. It was found that binding energies decrease almost linearly as θ increases from ∼0.08ML, with this effect being stronger for double-species co-adsorbed systems than for single-species adsorption cases. The activation energies also decrease as θ increases, with the lateral interactions between the reactants being the major contributor to the overall energy barrier.