Structural Changes in Monolayer Cobalt Oxides under Ambient Pressure CO and O2 Studied by In Situ Grazing-Incidence X-ray Absorption Fine Structure Spectroscopy
Journal article, 2022

We have used grazing incidence X-ray absorption fine structure spectroscopy at the cobalt K-edge to characterize monolayer CoO films on Pt(111) under ambient pressure exposure to CO and O2, with the aim of identifying the Co phases present and their transformations under oxidizing and reducing conditions. X-ray absorption near edge structure (XANES) spectra show clear changes in the chemical state of Co, with the 2+ state predominant under CO exposure and the 3+ state predominant under O2-rich conditions. Extended X-ray absorption fine structure spectroscopy (EXAFS) analysis shows that the CoO bilayer characterized in ultrahigh vacuum is not formed under the conditions used in this study. Instead, the spectra acquired at low temperatures suggest formation of cobalt hydroxide and oxyhydroxide. At higher temperatures, the spectra indicate dewetting of the film and suggest formation of bulklike Co3O4 under oxidizing conditions. The experiments demonstrate the power of hard X-ray spectroscopy to probe the structures of well-defined oxide monolayers on metal single crystals under realistic catalytic conditions.


Dorotea Gajdek

Lund University

Malmö university

P. A. T. Olsson

Malmö university

Lund University

Sara Blomberg

Lund University

Johan Gustafsson

Lund University

Per-Anders Carlsson

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry

Dörthe Haase

Lund University

Edvin Lundgren

Lund University

L. R. Merte

Malmö university

Lund University

Journal of Physical Chemistry C

1932-7447 (ISSN) 1932-7455 (eISSN)

Vol. 126 7 3411-3418

Subject Categories

Inorganic Chemistry

Atom and Molecular Physics and Optics

Materials Chemistry





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4/5/2022 5