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  Atomically Defined Co3O4(111) Thin Films Prepared in Ultrahigh Vacuum: Stability under Electrochemical Conditions

Faisal, F., Bertram, M., Stumm, C., Cherevko, S., Geiger, S., Kasian, O., et al. (2018). Atomically Defined Co3O4(111) Thin Films Prepared in Ultrahigh Vacuum: Stability under Electrochemical Conditions. The Journal of Physical Chemistry C, 122(13), 7236-7248. doi:10.1021/acs.jpcc.8b00558.

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Item Permalink: http://hdl.handle.net/21.11116/0000-0001-E821-4 Version Permalink: http://hdl.handle.net/21.11116/0000-0001-E822-3
Genre: Journal Article

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 Creators:
Faisal, Firas1, Author              
Bertram, Manon1, Author              
Stumm, Corinna1, Author              
Cherevko, Serhiy2, 3, Author              
Geiger, Simon2, Author              
Kasian, Olga2, Author              
Lykhach, Yaroslava1, Author              
Lytken, Ole4, Author              
Mayrhofer, Karl Johann Jakob2, 3, Author              
Brummel, Olaf1, Author              
Libuda, Jörg1, 5, Author              
Affiliations:
1Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany, persistent22              
2Electrocatalysis, Interface Chemistry and Surface Engineering, Max-Planck-Institut für Eisenforschung GmbH, Max Planck Society, ou_1863354              
3Helmholtz-Institute Erlangen-Nuremberg for Renewable Energy (IEK-11), Forschungszentrum Jülich, Egerlandstrasse 3, 91058 Erlangen, Germany, ou_persistent22              
4Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, Erlangen, Germany, persistent22              
5Erlangen Catalysis Resource Center, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany, persistent22              

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Free keywords: Absorption spectroscopy; Anodic oxidation; Chemical stability; Cobalt compounds; Corrosion rate; Crystal atomic structure; Cyclic voltammetry; Dissolution; Electrolytes; Electrons; Film preparation; Inductively coupled plasma mass spectrometry; Mass spectrometers; Single crystals; Thin films; Ultrahigh vacuum; X ray photoelectron spectroscopy, Accelerated oxidations; Chemical transformations; Electrochemical conditions; Electrochemical environments; Infrared reflection absorption spectroscopy; Structural stabilities; Surface science approaches; X-ray photoelectron spectroscopy studies, Oxide films
 Abstract: We have explored the stability, the structure, and the chemical transformations of atomically defined Co3O4(111) thin films under electrochemical conditions. The well-ordered Co3O4(111) films were prepared on an Ir(100) single crystal under ultrahigh vacuum (UHV) conditions and subsequently transferred and characterized in the electrochemical environment by means of cyclic voltammetry (CV), scanning flow cell inductively coupled plasma mass spectrometry (SCF-ICP-MS), and electrochemical infrared reflection absorption spectroscopy (EC-IRRAS). We have found that the Co3O4(111) films are stable in phosphate buffer at pH 10 at potentials between 0.33 to 1.33 VRHE. In the corresponding potential range, the corrosion rates established by means of SCF-ICP-MS were well below 0.1 monolayer per hour. Additionally, low-energy electron diffraction (LEED) and X-ray photoelectron spectroscopy (XPS) studies have shown that the long-range order, the thickness, and the composition of the films were preserved under electrochemical conditions. Disintegration of the film and formation of holes after repeated potential cycling within the stability window were ruled out by EC-IRRAS using CO as a probe molecule. In general, the stability of the Co3O4(111) films depends critically on both the pH and electrode potential. Increasing the pH from 10 to 12 compromised the structural stability of the Co3O4(111) films due to faster redox processes at the surface. In particular, we observed accelerated oxidation of cobalt followed by the formation of oxyhydroxide during the anodic scan and accelerated reduction to cobalt hydroxides during the cathodic scan. Decreasing the pH from pH 10 to pH 8, on the other hand, led to faster dissolution, in particular at potentials below 0.2 VRHE, where the dissolution rate increased rapidly due to formation of soluble Co(II) species. Our studies demonstrate that thin well-ordered oxide films prepared in UHV can be transferred into the electrochemical environment while preserving their atomic surface structure if the conditions are chosen carefully. This opens a surface science approach to atomically defined oxide-electrolyte interfaces. © 2018 American Chemical Society.

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Language(s): eng - English
 Dates: 2018-04-05
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Method: Peer
 Identifiers: DOI: 10.1021/acs.jpcc.8b00558
BibTex Citekey: Faisal20187236
 Degree: -

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Title: The Journal of Physical Chemistry C
  Abbreviation : J. Phys. Chem. C
Source Genre: Journal
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Publ. Info: Washington, D.C. : American Chemical Society
Pages: - Volume / Issue: 122 (13) Sequence Number: - Start / End Page: 7236 - 7248 Identifier: ISSN: 1932-7447
CoNE: /journals/resource/954926947766