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Operando XANES Reveals the Chemical State of Iron-Oxide Monolayers During Low-Temperature CO Oxidation

Gajdek, Dorotea LU ; Wallander, Harald J. LU ; Abbondanza, Giuseppe LU ; Harlow, Gary S. LU ; Gustafson, Johan LU ; Blomberg, Sara LU ; Carlsson, Per Anders ; Just, Justus LU orcid ; Lundgren, Edvin LU and Merte, Lindsay R. LU (2024) In ChemPhysChem
Abstract

We have used grazing incidence X-ray absorption near edge spectroscopy (XANES) to investigate the behavior of monolayer FeO (Formula presented.) films on Pt(111) under near ambient pressure CO oxidation conditions with a total gas pressure of 1 bar. Spectra indicate reversible changes during oxidation and reduction by O (Formula presented.) and CO at 150 °C, attributed to a transformation between FeO bilayer and FeO (Formula presented.) trilayer phases. The trilayer phase is also reduced upon heating in CO+O (Formula presented.), consistent with a Mars-van-Krevelen type mechanism for CO oxidation. At higher temperatures, the monolayer film dewets the surface, resulting in a loss of the observed reducibility. A similar iron oxide film... (More)

We have used grazing incidence X-ray absorption near edge spectroscopy (XANES) to investigate the behavior of monolayer FeO (Formula presented.) films on Pt(111) under near ambient pressure CO oxidation conditions with a total gas pressure of 1 bar. Spectra indicate reversible changes during oxidation and reduction by O (Formula presented.) and CO at 150 °C, attributed to a transformation between FeO bilayer and FeO (Formula presented.) trilayer phases. The trilayer phase is also reduced upon heating in CO+O (Formula presented.), consistent with a Mars-van-Krevelen type mechanism for CO oxidation. At higher temperatures, the monolayer film dewets the surface, resulting in a loss of the observed reducibility. A similar iron oxide film prepared on Au(111) shows little sign of reduction or oxidation under the same conditions. The results highlight the unique properties of monolayer FeO and the importance of the Pt support in this reaction. The study furthermore demonstrates the power of grazing-incidence XAFS for in situ studies of these model catalysts under realistic conditions.

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; ; ; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
epub
subject
keywords
Heterogeneous catalysis, Iron oxide, Operando, Thin films, XAFS
in
ChemPhysChem
publisher
John Wiley & Sons Inc.
external identifiers
  • pmid:39403857
  • scopus:85209646728
ISSN
1439-4235
DOI
10.1002/cphc.202400835
language
English
LU publication?
yes
id
26d044b5-8ce0-4e32-87ad-653d60def239
date added to LUP
2025-02-13 14:35:14
date last changed
2025-06-20 00:26:46
@article{26d044b5-8ce0-4e32-87ad-653d60def239,
  abstract     = {{<p>We have used grazing incidence X-ray absorption near edge spectroscopy (XANES) to investigate the behavior of monolayer FeO (Formula presented.) films on Pt(111) under near ambient pressure CO oxidation conditions with a total gas pressure of 1 bar. Spectra indicate reversible changes during oxidation and reduction by O (Formula presented.) and CO at 150 °C, attributed to a transformation between FeO bilayer and FeO (Formula presented.) trilayer phases. The trilayer phase is also reduced upon heating in CO+O (Formula presented.), consistent with a Mars-van-Krevelen type mechanism for CO oxidation. At higher temperatures, the monolayer film dewets the surface, resulting in a loss of the observed reducibility. A similar iron oxide film prepared on Au(111) shows little sign of reduction or oxidation under the same conditions. The results highlight the unique properties of monolayer FeO and the importance of the Pt support in this reaction. The study furthermore demonstrates the power of grazing-incidence XAFS for in situ studies of these model catalysts under realistic conditions.</p>}},
  author       = {{Gajdek, Dorotea and Wallander, Harald J. and Abbondanza, Giuseppe and Harlow, Gary S. and Gustafson, Johan and Blomberg, Sara and Carlsson, Per Anders and Just, Justus and Lundgren, Edvin and Merte, Lindsay R.}},
  issn         = {{1439-4235}},
  keywords     = {{Heterogeneous catalysis; Iron oxide; Operando; Thin films; XAFS}},
  language     = {{eng}},
  publisher    = {{John Wiley & Sons Inc.}},
  series       = {{ChemPhysChem}},
  title        = {{Operando XANES Reveals the Chemical State of Iron-Oxide Monolayers During Low-Temperature CO Oxidation}},
  url          = {{http://dx.doi.org/10.1002/cphc.202400835}},
  doi          = {{10.1002/cphc.202400835}},
  year         = {{2024}},
}