Persistence of Ce<sup>3+</sup> species on the surface of ceria during redox cycling: a modulated chemical excitation investigation
<i>Operando</i> resonant photoelectron spectroscopy (RPES) combined with modulated chemical excitation revealed the dynamic evolution of Ce<sup>3+</sup>/Ce<sup>4+</sup> redox states at the surface of CeO<sub>2</sub> during the CO oxidation reaction. Using alternating CO and O<sub>2</sub> pulses as chemically modulated signals, we monitored the surface states in the valence band region, unveiling the evolution of electronic structure during the catalytic process. The analysis with different gas flow ratios revealed that under CO-rich conditions (CO : O<sub>2</sub> ≥ 1), only partial conversion from Ce<sup>3+</sup> to Ce<sup>4+</sup> occurred. In contrast, complete Ce<sup>3+</sup> to Ce<sup>4+</sup> conversion was achieved when pulsing O<sub>2</sub> into O<sub>2</sub>-rich environments. Furthermore, we find that intermediate oxygen species, such as peroxo and OH, impact the conversion of Ce<sup>3+</sup> and Ce<sup>4+</sup>. These oxygenated species coexist between 330 °C and 360 °C in pure O<sub>2</sub>, while above 390 °C only OH groups remain stable on the ceria surface.
Authors
- Medhat Ibrahim (ORCID: https://orcid.org/0000-0002-9698-0837)
- Cyril Hachemi (ORCID: https://orcid.org/0000-0003-0912-5494)
- Hanna Dib (ORCID: https://orcid.org/0000-0001-8845-9323)
- Jan Knudsen (ORCID: https://orcid.org/0000-0002-8280-7638)
- M. Debbichi (ORCID: https://orcid.org/0000-0003-0332-5954)
- S. Loridant (ORCID: https://orcid.org/0000-0001-8590-433X)
- Helena Kaper (ORCID: https://orcid.org/0000-0001-8048-9018)
- Michaël Badawi (ORCID: https://orcid.org/0000-0002-3504-4180)
- Luis Cardenas (ORCID: https://orcid.org/0000-0003-0643-0784)
- Calley Eads (ORCID: https://orcid.org/0000-0001-9534-353X)
Institutions
- Université Claude Bernard Lyon 1 (FR)
- Saint-Gobain (France) (FR)
- Centre National de la Recherche Scientifique (FR)
- University of Monastir (TN)
- Lund University (SE)
- MAX IV Laboratory (SE)
- Institut de Recherches sur la Catalyse et l'Environnement de Lyon (FR)
- Université de Lorraine (FR)
Publication Details
- Journal
- Physical Chemistry Chemical Physics
- Published
- 2025-01-01
- DOI
- https://doi.org/10.1039/d5cp01283j
- Citations
- 3
- Primary Topic
- Catalytic Processes in Materials Science
- Type
- article
- Field-Weighted Citation Impact
- 1.55
Funders
- Agence Nationale de la Recherche
- VINNOVA
- Svenska Forskningsrådet Formas
- Vetenskapsrådet
- Grand Équipement National De Calcul Intensif
- Université de Lyon
- LABEX iMUST
- CHIST-ERA