Berlin 2008 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 37: Vibrational Spectroscopy of Nanolayers with Optical Probes

DS 37.1: Hauptvortrag

Freitag, 29. Februar 2008, 13:30–14:00, H 2013

Ambient pressure spectroscopy of catalytically active nano-structures: Mind the gap! — •Günther Rupprechter — Institute of Materials Chemistry, Vienna University of Technology, Veterinärplatz 1, A-1210 Vienna, Austria

Recent advances in model catalysis and in spectroscopic methods that can operate at ambient pressure now enable us to investigate a catalyst in its active state, i.e. while it is functioning. Polarization-modulated infrared spectroscopy, sum frequency generation, and high-pressure photoelectron spectroscopy allow monitoring the transformation of catalysts from the "as-prepared" to the "active-state", which may involve pronounced changes in catalyst structure and composition. The ultimate goal is the characterization of the active sites. A number of case studies are presented for Pd-based catalysts (single crystals, thin films, oxide supported nanoparticles), that illustrate the dynamic behavior of catalytically active surfaces, with emphasis on the activity of Pd surface oxides for CO and methanol oxidation, and on surface carbonate formation. There is clearly a need to "mind the gap" between investigations under ultrahigh vacuum and those at ambient pressure, as well as to account for the inherent differences between supported nanoparticles and extended single crystal surfaces.