Quantitative depth profiling of Ce 3+ in Pt/CeO 2 by in situ high-energy XPS in a hydrogen atmosphere

Kato, Shunsuke; Ammann, Markus; Huthwelker, Thomas; Paun, Cristina; Lampimäki, Markus; Lee, Ming-Tao; Rothensteiner, Matthäus; van Bokhoven, Jeroen A. (2015). Quantitative depth profiling of Ce 3+ in Pt/CeO 2 by in situ high-energy XPS in a hydrogen atmosphere. Physical Chemistry Chemical Physics, 17(7), pp. 5078-5083. Royal Society of Chemistry 10.1039/C4CP05643D

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The redox property of ceria is a key factor in the catalytic activity of ceria-based catalysts. The oxidation state of well-defined ceria nanocubes in gas environments was analysed in situ by a novel combination of near-ambient pressure X-ray Photoelectron Spectroscopy (XPS) and high-energy XPS at a synchrotron X-ray source. In situ high-energy XPS is a promising new tool to determine the electronic structure of matter under defined conditions. The aim was to quantitatively determine the degree of cerium reduction in a nano-structured ceria-supported platinum catalyst as a function of the gas environment. To obtain a non-destructive depth profile at near-ambient pressure, in situ high-energy XPS analysis was performed by varying the kinetic energy of photoelectrons from 1 to 5 keV, and, thus, the probing depth. In ceria nanocubes doped with platinum, oxygen vacancies formed only in the uppermost layers of ceria in an atmosphere of 1 mbar hydrogen and 403 K. For pristine ceria nanocubes, no change in the cerium oxidation state in various hydrogen or oxygen atmospheres was observed as a function of probing depth. In the absence of platinum, hydrogen does not dissociate and, thus, does not lead to reduction of ceria.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry

UniBE Contributor:

Ammann, Markus

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry

ISSN:

1463-9076

Publisher:

Royal Society of Chemistry

Language:

English

Submitter:

Franziska Bornhauser-Rufer

Date Deposited:

17 Mar 2015 09:09

Last Modified:

14 Jan 2016 08:48

Publisher DOI:

10.1039/C4CP05643D

BORIS DOI:

10.7892/boris.64716

URI:

https://boris.unibe.ch/id/eprint/64716

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