Operando XANES Reveals the Chemical State of Iron-Oxide Monolayers During Low-Temperature CO Oxidation
Journal article, 2024
We have used grazing incidence X-ray absorption near edge spectroscopy (XANES) to investigate the behavior of monolayer FeO x ${_x }$ 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 2 ${_2 }$ and CO at 150 degrees C, attributed to a transformation between FeO bilayer and FeO 2 ${_2 }$ trilayer phases. The trilayer phase is also reduced upon heating in CO+O 2 ${_2 }$ , 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.
Thin films
Operando
XAFS
Iron oxide
Heterogeneous catalysis
Author
Dorotea Gajdek
Malmö university
Lund University
Harald J. Wallander
Lund University
Malmö university
Giuseppe Abbondanza
Chalmers, Physics, Chemical Physics
Gary S. Harlow
University of Oregon
Johan Gustafson
Lund University
Sara Blomberg
Lund University
Per-Anders Carlsson
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
Justus Just
Lund University
Edvin Lundgren
Lund University
Lindsay R. Merte
Lund University
Malmö university
ChemPhysChem
1439-4235 (ISSN) 1439-7641 (eISSN)
Vol. In PressDevelopment of X-ray techniques and new Ga-zeotypes for production of green aromatics
Swedish Research Council (VR) (2023-06344), 2024-01-01 -- 2027-12-31.
Subject Categories (SSIF 2011)
Condensed Matter Physics
DOI
10.1002/cphc.202400835
PubMed
39403857