Abstract
In order to explain the experimentally found catalytic characteristics of we have performed a comprehensive density functional study of these systems and their ability to (co)adsorb CO and molecules. Starting from the carefully determined ground-state structures we have analyzed binding mechanisms, the influence of spin-orbit coupling, and charge redistributions in . Experimentally were found to be inactive under a mixed atmosphere. We show that strongly binds to that prevents coadsorption. Although a catalytic reaction cycle towards CO oxidation, analogous to the gas phase reaction involving , is energetically possible for , the cluster will get blocked by a strongly bound CO. On the other hand, the catalytic activity of could be explained by their ability to coadsorb CO and , hence indicating the occurrence of a Langmuir-Hinshelwood-type reaction mechanism for these clusters.
- Received 24 September 2009
DOI:https://doi.org/10.1103/PhysRevB.81.195443
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