Regensburg 2019 – wissenschaftliches Programm
O 81.4: Hauptvortrag
Donnerstag, 4. April 2019, 12:00–12:30, H24
High energy surface x-ray diffraction from surfaces and particles in operando catalysis — •Uta Hejral1, Stefano Albertin1, Mikhail Shipilin2,3, Jianfeng Zhou1, Sebastian Pfaff1, Sara Blomberg1, Johan Zetterberg1, Johan Gustafson1, Andreas Stierle2, and Edvin Lundgren1 — 1Lund University, Lund, Sweden — 2DESY, Hamburg, Germany — 3Stockholm University, Stockholm, Sweden
Catalysts are widely employed in chemical industry, in fuel cells and car exhaust control systems, where they accelerate desired chemical reactions. To improve catalyst performance, a time-resolved atomic-scale understanding of the interplay between the catalyst surface structures, the catalytic activity/selectivity, and the gas phase surrounding the catalyst surface is inevitable.
High energy surface x-ray diffraction (HESXRD) provides a fast data acquisition for the structural characterization of model catalyst samples under operando conditions. We demonstrate how we used HESXRD to study the shape-dependent sintering of supported Pt-Rh alloy nanoparticles during CO oxidation. Flat-shaped Pt-rich particles underwent strong vertical sintering, while Rh-rich compact-shaped particles proved to be sinter-resistant. In another experiment we combined HESXRD with gas phase diagnostics to investigate the structure-gas phase correlation during self-sustained reaction oscillations over Pd(100) during CO oxidation. We found that the surface features epitaxial PdO(101) bulk oxide decorated by metallic Pd islands on top, which play a crucial role for the self-sustained oscillations.