Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 49: Poster: Nanostructures on Surfaces I

O 49.14: Poster

Dienstag, 13. März 2018, 18:15–20:30, Poster A

Reactivity of CO on Sulfur-Passivated Graphene-Supported Platinum Nanocluster Arrays — Fabian Düll, Udo Bauer, Florian Späth, Philipp Bachmann, Johann Steinhauer, Hans-Peter Steinrück, and •Christian Papp — Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany

Poisoning of heterogeneous catalysts, in particular platinum, by sulfur and its oxides is of a hot topic in catalysis for decades.

Utilizing the intrinsic Moiré pattern of graphene on Rh(111) as a template and chemically inert support, Pt nanocluster arrays were grown.[1] They were then poisoned with sulfur via thermal reduction of SO2. To understand the changes that occur upon sulfur poisoning, the adsorption and desorption of the probe molecule CO were investigated. The changes in the adsorption behavior for several preadsorbed sulfur coverages were studied with in situ high-resolution XPS. Three different CO species can be distinguished: top and bridge bonded CO on terrace sites and CO at step sites. Sulfur blocks those adsorption sites to different degrees. While on-top and step sites are highly affected, bridge sites are affected to a lower degree. These results will be compared to measurements on the stepped Pt(322) and Pt(355) surfaces.[2] Upon annealing, a displacement of sulfur from step to terrace sites by CO occurs around 330 K, which is reversed after desorption of the CO. Such a behavior was also found on stepped platinum crystals.

[1] K. Gotterbarm et al., ACS Catal. (2015) 2397-2403.

[2] R. Streber et al., Chem. Phys. Lett. 452 (2008) 94-98.