Thermal evolution of cobalt deposits on Co3O4(111): Atomically dispersed cobalt, two-dimensional CoO islands, and metallic Co nanoparticles

Journal article
(Original article)


Publication Details

Author(s): Mehl S, Ferstl P, Schuler M, Toghan A, Brummel O, Hammer L, Schneider MA, Libuda J
Journal: Physical Chemistry Chemical Physics
Publisher: Royal Society of Chemistry
Publication year: 2015
Volume: 17
Journal issue: 36
Pages range: 23538-23546
ISSN: 1463-9076
eISSN: 1463-9084
Language: English


Abstract


Cobalt oxide nanomaterials show high activity in several catalytic reactions thereby offering the potential to replace noble metals in some applications. We have developed a well-defined model system for partially reduced cobalt oxide materials aiming at a molecular level understanding of cobalt-oxide-based catalysis. Starting from a well-ordered Co3O4(111) film on Ir(100), we modified the surface by deposition of metallic cobalt. Growth, structure, and adsorption properties of the cobalt-modified surface were investigated by scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), and infrared reflection absorption spectroscopy (IRAS) using CO as a probe molecule. The deposition of a submonolayer of cobalt at 300 K leads to the formation of atomically dispersed cobalt ions distorting the surface layer of the Co3O4 film. Upon annealing to 500 K the Co ions are incorporated into the surface layer forming ordered two-dimensional CoO islands on the Co3O4 grains. At 700 K, Co ions diffuse from the CoO islands into the bulk and the ordered Co3O4(111) surface is restored. Deposition of larger amounts of Co at 300 K leads to formation of metallic Co aggregates on the dispersed cobalt phase. The metallic particles sinter at 500 K and diffuse into the bulk at 700 K. Depending on the degree of bulk reduction, extended Co3O4 grains switch to the CoO(111) structure. All above structures show characteristic CO adsorption behavior and can therefore be identified by IR spectroscopy of adsorbed CO.



FAU Authors / FAU Editors

Brummel, Olaf Dr.
Lehrstuhl für Physikalische Chemie II
Ferstl, Pascal
Professur für Experimentalphysik
Hammer, Lutz Dr.
Lehrstuhl für Festkörperphysik
Libuda, Jörg Prof. Dr.
Professur für Physikalische Chemie
Mehl, Sascha
Lehrstuhl für Physikalische Chemie II
Schneider, M. Alexander Prof. Dr.
Professur für Experimentalphysik
Schuler, Marina
Lehrstuhl für Festkörperphysik


Additional Organisation
Exzellenz-Cluster Engineering of Advanced Materials


How to cite

APA:
Mehl, S., Ferstl, P., Schuler, M., Toghan, A., Brummel, O., Hammer, L.,... Libuda, J. (2015). Thermal evolution of cobalt deposits on Co3O4(111): Atomically dispersed cobalt, two-dimensional CoO islands, and metallic Co nanoparticles. Physical Chemistry Chemical Physics, 17(36), 23538-23546. https://dx.doi.org/10.1039/c5cp03922c

MLA:
Mehl, Sascha, et al. "Thermal evolution of cobalt deposits on Co3O4(111): Atomically dispersed cobalt, two-dimensional CoO islands, and metallic Co nanoparticles." Physical Chemistry Chemical Physics 17.36 (2015): 23538-23546.

BibTeX: 

Last updated on 2019-19-02 at 15:24