Regensburg 2022 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 3: Focus Session: Single Atom Catalysis 1

O 3.6: Vortrag

Montag, 5. September 2022, 12:00–12:15, H4

Nature of the active species in low-temperature CO oxidation over Pt-CeO2 model catalysts — •Alexander Simanenko¹, Maximilian Kastenmeier¹, Lesia Piliai², Tomáš Skála², Yuliia Kosto², Nataliya Tsud², Sascha Mehl³, Mykhailo Vorokhta², Iva Matolínová², Yaroslava Lykhach¹, and Jörg Libuda¹ — ¹Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany — ²Charles University, Prague, Czech Republic — ³Elettra-Sincrotrone Trieste SCpA, Basovizza-Trieste, Italy

The low-temperature CO oxidation has wide applications in energy production and exhaust gas cleaning. Pt-CeO2 catalysts with high Pt content allow achieving 100% CO conversion below room temperature. We investigated the nature of active sites on Pt-CeO2 catalysts under the conditions of low-temperature CO oxidation by means of synchrotron radiation photoelectron spectroscopy, resonant photoemission spectroscopy, and near ambient pressure XPS. Model Pt-CeO2 systems were prepared by reactive physical vapor co-deposition and annealed in UHV or O2 in order to obtain different types of platinum species on the surface. These included mainly Pt2+ species accompanied by a small number of Pt4+ species that were reduced to Pt2+ or metallic Pt during annealing. Exclusively, stable Pt4+ species were formed on a thick Pt-CeO2 catalyst with high Pt content after annealing in oxygen at NAP conditions. The results of our study showed that there is no reduction or oxidation of the Pt-CeO2 catalysts by CO below 450 K. These observations suggest that low-temperature CO oxidation on Pt-CeO2 catalyst does not follow a Mars-Van Krevelen mechanism.