Structural Changes in Monolayer Cobalt Oxides under Ambient Pressure CO and O2 Studied by In Situ Grazing-Incidence X-ray Absorption Fine Structure Spectroscopy
Artikel i vetenskaplig tidskrift, 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.

Författare

Dorotea Gajdek

Lunds universitet

Malmö universitet

P. A. T. Olsson

Malmö universitet

Lunds universitet

Sara Blomberg

Lunds universitet

Johan Gustafsson

Lunds universitet

Per-Anders Carlsson

Chalmers, Kemi och kemiteknik, Tillämpad kemi, Per-Anders Carlsson Group

Dörthe Haase

Lunds universitet

Edvin Lundgren

Lunds universitet

L. R. Merte

Malmö universitet

Lunds universitet

Journal of Physical Chemistry C

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

Vol. 126 7 3411-3418

Ämneskategorier

Oorganisk kemi

Atom- och molekylfysik och optik

Materialkemi

DOI

10.1021/acs.jpcc.1c10284

PubMed

35242268

Mer information

Senast uppdaterat

2022-04-05