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Spillover Reoxidation of Ceria Nanoparticles

Grinter, DC; Muryn, C; Sala, A; Yim, C-M; Pang, CL; Menteş, TO; Locatelli, A; (2016) Spillover Reoxidation of Ceria Nanoparticles. The Journal of Physical Chemistry C , 120 (20) , Article .. 10.1021/acs.jpcc.6b03670. Green open access

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Abstract

Interest in resolving the mechanisms behind ceria's activity has been intense due to the numerous industrial applications including those in heterogeneous catalysis. In this work, we study the reduction and reoxidation of ultrathin CeO2(111) nanoislands on Rh(111) and Pt(111) substrates, so-called inverse model catalysts, with a combination of real and reciprocal space techniques based on X-ray photoemission electron microscopy (XPEEM) and low energy electron microscopy. Soft X-ray microfocused illumination was employed to reduce the ceria islands, which we are able to control by varying the oxygen partial pressure within the measurement chamber. Low energy electron diffraction measurements of the irradiated ceria films demonstrate the formation of an ordered array of oxygen vacancies leading to a (√7 × √7)R19.1° superstructure attributed to the ι-phase (Ce7O12)(111). Resonant photoelectron spectroscopy provides the required high sensitivity to detect small changes in Ce3+ concentration. The high spatial resolution of the XPEEM allows us to determine that the reduction of the ceria occurs initially at the interface of the islands with the Rh support. Reoxidation of the CeO2–x(111) to CeO2(111) proceeds via spillover of activated oxygen adsorbed on the Rh(111) surface as a (2 × 2) overlayer. Our results highlight the important role that the noble metal plays in the regeneration of the stoichiometric ceria surface, a vital step in many reactions on ceria. This differs from the commonly proposed Mars–van Krevelen model in which reoxidation involves direct reaction of the ceria with O2.

Type: Article
Title: Spillover Reoxidation of Ceria Nanoparticles
Open access status: An open access version is available from UCL Discovery
DOI: 10.1021/acs.jpcc.6b03670
Publisher version: http://dx.doi.org/10.1021/acs.jpcc.6b03670
Language: English
Additional information: Copyright © 2016 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Physical Chemistry C after peer review and technical editing by the publisher. The final edited and published work is available at http://dx.doi.org/10.1021/acs.jpcc.6b03670
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
URI: https://discovery.ucl.ac.uk/id/eprint/1497154
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