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Atomic Structure and Valence State of Cobalt Nanocrystals on Carbon under Syngas Versus Hydrogen Reduction

Makgae, Ofentse A. LU ; Phaahlamohlaka, Tumelo N. ; Yao, Benzhen ; Schuster, Manfred E. ; Slater, Thomas J.A. ; Edwards, Peter P. ; Coville, Neil J. ; Liberti, Emanuela and Kirkland, Angus I. (2022) In Journal of Physical Chemistry C 126(14). p.6325-6333
Abstract

The composition of the reducing gas in the activation of Co Fischer-Tropsch synthesis catalysts determines the nature of the catalytically active Co species. This study reports on the effect of H2versus syngas (H2/CO = 2) on the reducibility of Co3O4nanoparticles supported on hollow carbon spheres, using ex situ and in situ high-resolution aberration-corrected analytical electron microscopy. High-resolution images revealed twinned fcc Co particles encapsulated in carbon from syngas treatment while H2-treated particles were mostly CoO. Moreover, the electron energy loss of the Co-L3,2and O-K edge fine structures show improved reducibility in syngas than in H2at... (More)

The composition of the reducing gas in the activation of Co Fischer-Tropsch synthesis catalysts determines the nature of the catalytically active Co species. This study reports on the effect of H2versus syngas (H2/CO = 2) on the reducibility of Co3O4nanoparticles supported on hollow carbon spheres, using ex situ and in situ high-resolution aberration-corrected analytical electron microscopy. High-resolution images revealed twinned fcc Co particles encapsulated in carbon from syngas treatment while H2-treated particles were mostly CoO. Moreover, the electron energy loss of the Co-L3,2and O-K edge fine structures show improved reducibility in syngas than in H2at 350 °C. The effect of high temperature on the reducibility of the Co3O4nanoparticles is also explored. Carbon fiber encapsulation of twinned fcc Co particles observed during the syngas treatment provides sinter resistance at high temperatures. Both ex situ and in situ results indicate that syngas activation is efficient for obtaining highly reduced Co nanoparticles at lower temperatures.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Physical Chemistry C
volume
126
issue
14
pages
9 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:85128220766
ISSN
1932-7447
DOI
10.1021/acs.jpcc.2c00482
language
English
LU publication?
yes
id
d5ab85a5-f08c-41fd-98ac-e2eacc20b8d0
date added to LUP
2022-07-05 14:17:07
date last changed
2023-11-19 08:38:27
@article{d5ab85a5-f08c-41fd-98ac-e2eacc20b8d0,
  abstract     = {{<p>The composition of the reducing gas in the activation of Co Fischer-Tropsch synthesis catalysts determines the nature of the catalytically active Co species. This study reports on the effect of H<sub>2</sub>versus syngas (H<sub>2</sub>/CO = 2) on the reducibility of Co<sub>3</sub>O<sub>4</sub>nanoparticles supported on hollow carbon spheres, using ex situ and in situ high-resolution aberration-corrected analytical electron microscopy. High-resolution images revealed twinned fcc Co particles encapsulated in carbon from syngas treatment while H<sub>2</sub>-treated particles were mostly CoO. Moreover, the electron energy loss of the Co-L<sub>3,2</sub>and O-K edge fine structures show improved reducibility in syngas than in H<sub>2</sub>at 350 °C. The effect of high temperature on the reducibility of the Co<sub>3</sub>O<sub>4</sub>nanoparticles is also explored. Carbon fiber encapsulation of twinned fcc Co particles observed during the syngas treatment provides sinter resistance at high temperatures. Both ex situ and in situ results indicate that syngas activation is efficient for obtaining highly reduced Co nanoparticles at lower temperatures.</p>}},
  author       = {{Makgae, Ofentse A. and Phaahlamohlaka, Tumelo N. and Yao, Benzhen and Schuster, Manfred E. and Slater, Thomas J.A. and Edwards, Peter P. and Coville, Neil J. and Liberti, Emanuela and Kirkland, Angus I.}},
  issn         = {{1932-7447}},
  language     = {{eng}},
  month        = {{04}},
  number       = {{14}},
  pages        = {{6325--6333}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{Journal of Physical Chemistry C}},
  title        = {{Atomic Structure and Valence State of Cobalt Nanocrystals on Carbon under Syngas Versus Hydrogen Reduction}},
  url          = {{http://dx.doi.org/10.1021/acs.jpcc.2c00482}},
  doi          = {{10.1021/acs.jpcc.2c00482}},
  volume       = {{126}},
  year         = {{2022}},
}