Adsorbate-Oxide Interactions during the $NO+CO$ Reaction on MgO(100) Supported Pd Monolayer Films

The potential energy diagram for the $\mathrm{NO}+\mathrm{CO}$ reaction on 1, 2, and 3 monolayer (ML) Pd films supported by MgO(100) is calculated using density functional theory. Thin Pd films are generally found to be more reactive than thick films, with a notable exception for nitrogen adsorption on 2 ML $\mathrm{Pd}/\mathrm{MgO}\left(100\right)$. For this system an attractive through-the-metal adsorbate-oxide interaction of 0.5 eV is identified. Nitrogen adsorption is consequently estimated to provide a thermodynamic driving force for the reconstruction of MgO(100) supported 3 ML (or thicker) Pd clusters into thinner Pd clusters.