To optimize the catalytic functionality of cerium oxide it is important to understand the structural modifications associated with reduction and the role of the proximity of metals, which are often coupled with the oxide in the applications. For this purpose, the evolution of the short- and long-range structure of cerium oxide ultrathin epitaxial films and nanostructures supported on Pt(111) is investigated using X-ray absorption spectroscopy at the Ce L3 edge and surface X-ray diffraction, during reduction by thermal treatments in vacuum. In epitaxial nanoislands reduction is associated with a contraction of the Ce–O distance and with the appearance of Ce-Pt bonds. The formation of a phase with a (2 × 2) periodicity after a thermal treatment at 1023 K is ascribed to the formation of a Pt5Ce alloy. Films of 3 nm thickness do not show, on average, significant structural modifications with the same thermal treatment, consistent with the hypothesis that the reduction involves only the topmost surface layers and it does not influence significantly the bulk structure of the material. This study demonstrates a strong interaction between cerium oxide and platinum, which has implications for the reactivity and stability of catalysts based on metals combined with reducible oxides.

Structure of Reduced Cerium Oxide Ultrathin Films on Pt(111): Local Atomic Environment and Long-Range Order

Boscherini F.;
2020

Abstract

To optimize the catalytic functionality of cerium oxide it is important to understand the structural modifications associated with reduction and the role of the proximity of metals, which are often coupled with the oxide in the applications. For this purpose, the evolution of the short- and long-range structure of cerium oxide ultrathin epitaxial films and nanostructures supported on Pt(111) is investigated using X-ray absorption spectroscopy at the Ce L3 edge and surface X-ray diffraction, during reduction by thermal treatments in vacuum. In epitaxial nanoislands reduction is associated with a contraction of the Ce–O distance and with the appearance of Ce-Pt bonds. The formation of a phase with a (2 × 2) periodicity after a thermal treatment at 1023 K is ascribed to the formation of a Pt5Ce alloy. Films of 3 nm thickness do not show, on average, significant structural modifications with the same thermal treatment, consistent with the hypothesis that the reduction involves only the topmost surface layers and it does not influence significantly the bulk structure of the material. This study demonstrates a strong interaction between cerium oxide and platinum, which has implications for the reactivity and stability of catalysts based on metals combined with reducible oxides.
Pelli Cresi J.S.; Carla F.; Znaiguia R.; Isern H.; Benedetti F.; Gasperi G.; Amidani L.; Valeri S.; Boscherini F.; Luches P.
File in questo prodotto:
File Dimensione Formato  
11585_786673_postprint.pdf

embargo fino al 29/07/2021

Tipo: Postprint
Licenza: Licenza per accesso libero gratuito
Dimensione 930.65 kB
Formato Adobe PDF
930.65 kB Adobe PDF Visualizza/Apri
supp_info_rev.pdf

embargo fino al 29/07/2021

Tipo: File Supplementare
Licenza: Licenza per accesso libero gratuito
Dimensione 303.35 kB
Formato Adobe PDF
303.35 kB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/786673
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 0
  • ???jsp.display-item.citation.isi??? 0
social impact