Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 28: Heterogeneous catalysis II

O 28.2: Vortrag

Dienstag, 27. März 2012, 10:45–11:00, MA 042

CO adsorbtion and oxidation study on different types of Au clusters on C/W(110) — •Magdalena Bachmann, Norbert Memmel, and Erminald Bertel — Institute of Physical Chemistry, University of Innsbruck, Austria

In the last years gold nanoparticles on oxidic supports have gained great attention due to their catalytic activity for oxidation reactions. Despite 20 years of research, it is not clear if this unexpected behavior originates either from support effects (charge transfer etc.) or from intrinsic properties of the clusters (quantum size effect, number of low coordinated atoms etc.). We introduce two different carburized W(110) substrates for the growth of gold nanoclusters: On R(15x12)C/W(110) regularly spaced nanodot arrays with a cluster size of ≈ 7 atoms are formed, whereas on R(15x3)C/W(110) larger particles of bilayer height are fabricated. The catalytic properties of both systems are studied; CO combustion is chosen as a well-explored test reaction. As TPD measurements clearly indicate, CO is adsorbed on both types of clusters as well as on extended gold islands on the bare W(110) substrate. Although in-situ STM investigations on the influence of oxygen on the clusters suggest dissociation (which is regarded as the most crucial step), TPR experiments do not indicate the formation of CO₂. Probable reasons for these observations are discussed as well as the position of our findings within the field of research.