Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 52: Poster Wednesday: Adsorption and Catalysis 2
O 52.11: Poster
Mittwoch, 7. September 2022, 18:00–20:00, P4
The relation between structure sensitivity and doping of ceria(111) vs. ceria(100) — Emilia Pozarowska1, Linus Pleines2, Mauricio J. Prieto3, Liviu C. Tănase3, Lucas de Souza Caldas3, Aarti Tiwari3, Thomas Schmidt3, Jens Falta2, Carlos Morales1, and •Jan Ingo Flege1 — 1Applied Physics and Semiconductor Spectroscopy, BTU Cottbus-Senftenberg, Cottbus, Germany — 2Institute of Solid State Physics, University of Bremen, Bremen, Germany — 3Department of Interface Science, Fritz-Haber Institute, Berlin, Germany
CeOx-Cu inverse catalysts have been shown to convert CO2 into valuable chemicals through catalytic hydrogenation. The catalytic activity may further be enhanced by alloying ceria with trivalent, catalytically active metals, such as Sm, promoting the formation of Ce3+ active sites. In this work, the structural and chemical properties of (111)- and (100)- oriented CeOx islands alloyed with samarium were explored by low-energy electron microscopy and X-ray photoemission electron microscopy. After Sm deposition on the as-grown CeOx islands, the near-surface region of (100)-oriented CeOx is reduced after exposure to H2 at 470 ∘C, whereas the deeper layers as well as the whole (111)-oriented islands retain the Ce4+ state. Subsequent reoxidation with O2 leads to the complete Ce4+ state recovery, suggesting the healing of oxygen vacancies. Additional annealing at 470 ∘C induces samarium diffusion into the ceria matrix. Yet, subsequent exposure to H2 reduces neither the (111)- nor the (100)-oriented CeSmOx islands, suggesting a quite unexpected stability of this system.