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O: Fachverband Oberflächenphysik
O 52: Heterogeneous Catalysis and Surface Dynamics I
O 52.1: Talk
Wednesday, March 29, 2023, 10:30–10:45, TRE Phy
In-situ spectro-microscopy of single PtRh nanoparticles during oxidation — •Jagrati Dwivedi1, Lydia Bachmann1,2, Arno Jeromin1, Liviu C. Tănase3, Aarti Tiwari3, Lucas Caldas3, Thomas Schmidt3, Thomas F. Keller1,2, Beatriz Roldán Cuenya3, and Andreas Stierle1,2 — 1CXNS, Deutsches Elektronen-Synchrotron DESY, D-22607 Hamburg, Germany — 2Physics Department, University of Hamburg, D-20355 Hamburg, Germany — 3Department of Interface Science, Fritz-Haber-Institut der Max-Planck Gesellschaft, D-14195 Berlin, Germany
Heterogeneous catalysts are an integral part of industrial scale energy production, conversion and storage. However, a detailed understanding of how their shape, size, structural arrangement and chemical composition affect catalytic activity, selectivity and lifetime remains far from understood. The characterization under catalytic conditions remains challenging, therefore, a spectroscopic analysis of individual PtRh nanoparticles can provide direct evidence of the adsorbed species and their oxidation state. Here, we examined core-shell arranged PtRh nanoparticles on niobium-doped STO single crystals that were achieved by dewetting a homogeneous Pt film and subsequent overgrowth with Rh. Ex situ Scanning Auger Microscopy before and after the oxidation showed that the overgrown Rh is sintering. Spatially resolved in situ X-ray photoemission at BESSY II indicates the formation of Rh2O3 at partial oxygen pressure. While the nanoparticles surface composition reflects the oxidation and H2 reduction, the shape of the nanoparticles remains rather unchanged under the applied conditions.