Dresden 2009 – wissenschaftliches Programm

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SYCR: Symposium Chemical Reactions on Nanomaterials: Progress from in-situ Experimental Studies and Theoretical Investigations

SYCR 1: Chemical Reactions on Nanomaterials

SYCR 1.4: Hauptvortrag

Donnerstag, 26. März 2009, 16:00–16:30, BAR SCHÖ

In-situ microscopy of chemical reactions on transition metal surfaces — •Peter Sutter — Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973 (USA)

In catalytic chemistry on metals, distinct surface and thin-film phases generated under reaction conditions can strongly influence the activity and selectivity of the catalyst. Investigating the formation mechanisms, structure, and reactivity of nanoscale domains of these phases is challenging, since it requires experimental techniques that can acquire spectroscopic information with high spatial and temporal resolution during a chemical reaction.

In-situ low-energy electron microscopy allows observing the structure, electronic properties, and catalytic activity of evolving nanoscale surface phases in real time at elevated temperatures and gas pressures. We review the recent progress in this approach by discussing oxidation reactions on 4d late transition metals, such as ruthenium (Ru) and rhodium (Rh). The initial oxidation of Ru(0001), for instance, was predicted to involve the formation of a surface oxide as a precursor to the bulk oxide, which in turn is believed to be the primary active phase in oxidation catalysis in this system. By mapping multiple sets of spectroscopic data, in-situ microscopy not only identifies a more intricate competition between surface and bulk oxides, but also shows unexpected effects in oxidation catalysis due to the nanometer-scale heterogeneity of the surface, thus providing unique insight into the evolution and functionality of a catalytic surface system.