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The relation between structure sensitivity and doping of ceria(111) vs. ceria(100)

  • 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 quiteCeOx-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.show moreshow less

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Author: Emilia PozarowskaORCiD, Linus PleinesORCiD, Mauricio J. PrietoORCiD, Liviu Christian TănaseORCiD, Lucas de Souza CaldasORCiD, Aarti TiwariORCiD, Thomas SchmidtORCiD, Jens FaltaORCiD, Carlos MoralesORCiD, Jan Ingo FlegeORCiD
URL:https://www.dpg-verhandlungen.de/year/2022/conference/regensburg/part/o/session/52/contribution/11
ISSN:0420-0195
Title of the source (English):Verhandlungen der DPG
Publisher:Deutsche Physikalische Gesellschaft
Place of publication:Bad Honnef
Document Type:Image (poster)
Language:English
Year of publication:2022
Tag:Samarium alloying of cerium oxide; X-ray photoemission electron microscopy (PEEM); catalytic hydrogenation; healing of oxygen vacancies; low-energy electron microscopy (LEEM)
Series ; volume number:Verhandlungen der DPG
Faculty/Chair:Fakultät 1 MINT - Mathematik, Informatik, Physik, Elektro- und Informationstechnik / FG Angewandte Physik und Halbleiterspektroskopie
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