Chemical characterization of a zirconia-supported Pt cluster

Density functional theory calculations have been used to chemically characterize the properties of a cluster supported on the close-packed (101) surface of tetragonal zirconia. Adsorption of carbon monoxide, atomic oxygen, and their reaction forming CO2 was studied and compared to the same reactions over a free cluster and on the same cluster on top of the close-packed platinum surface. It is shown that the oxide support has a promotive influence on the adsorption of the investigated adsorbates. However, for this size of the cluster, the effect is dramatically reduced for more adsorbates, so that coadsorption and transition state energies are less favored in comparison to the other two systems. This implies that the crucial steps in the reaction are the approach of the adsorbates into neighboring sites for the supported systems, while the rate-limiting step on the free cluster is the formation Of CO2.