Berlin 2015 – scientific programme
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O: Fachverband Oberflächenphysik
O 82: Nanostructure at Surfaces: Dots and Clusters
O 82.1: Talk
Thursday, March 19, 2015, 10:30–10:45, MA 043
CO2 Activation on ultra-small Au particles on MgO Thin Films — •Christian Stiehler1, Florencia Calaza1, Martin Sterrer1, Niklas Nilius2, and Hans-Joachim Freund1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany — 2Carl von Ossietzky Universität Oldenburg, Institut für Physik, D-26111 Oldenburg, Germany
Metal particles exhibit favorable catalytic properties that are unknown for the respective bulk metals [1]. Although several reasons are discussed in the literature, the true origin for their enhanced activity remains unknown. Electron quantization and the associated band-gap opening at the Fermi level are certainly involved in the unusual catalytic response of the nano-islands. In this talk, we discuss the electronic structure of Au clusters that contain 50-200 atoms and are of monolayer height [2,3]. Simultaneously, we have probed the ability of the particles to bind and activate carbon dioxide (CO2), by using STM, XPS, TPD and IRAS measurements. The molecules preferentially bind along the cluster edge, at which a charge transfer from the electron-rich perimeter into the adsorbates takes place. Our talk addresses possible interrelations between the CO2 adsorption behavior and the quantized electronic structure of the gold islands.
[1] M. Valden et al., Sci 281, 1647 (1998)
[2] X. Lin et al., PLR 102, 2068011 (2009)
[3] C. Stiehler et al., PRB 88, 115415 (2014)