Predicting experimental signatures for the oxidation of magnesia supported palladium clusters by density functional theory
Fraunhofer Institut für Werkstoffmechanik, Wöhlerstraße 11, 79108 Freiburg, Germany
2 Freiburg Materials Research Center, Stefan-Meier-Straße 21, 79104 Freiburg, Germany
Revised: 8 May 2007
Published online: 1 June 2007
We showed in a recent density functional study that small palladium cluster on a MgO surface with F-centers can be oxidized to epitaxial PdxOy nano-oxides below room temperature . Here, we employ density functional theory in order to explore different methods for an experimental verification of the PdxOy formation. The electronic density of states (DOS) of bare, O2-decorated and of oxidized palladium cluster was calculated. For many cluster sizes a clear difference in the DOS could be observed allowing for a detection of the oxidation with surface sensitive spectroscopic methods. In addition, adsorption sites and stretch frequencies of a single CO molecule on bare and oxidized Pd4 clusters were calculated. While CO prefers hollow sites on Pd4, top adsorption sites are found for Pd4O2. Markedly different CO stretch frequencies indicate a possible discrimination of bare clusters and oxides by Fourier transform infrared spectroscopy.
PACS: 68.43.Fg – Adsorbate structure (binding sites, geometry) / 68.47.Jn – Clusters on oxide surfaces / 73.22.-f – Electronic structure of nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2007