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@PHDTHESIS{Hackl:844540,
author = {Hackl, Johanna Maria},
title = {{R}eduction properties of a model ceria catalyst at the
microscopic scale},
volume = {407},
school = {Universität Duisburg},
type = {Dissertation},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zenralbibliothek, Verlag},
reportid = {FZJ-2018-01947},
isbn = {978-3-95806-294-8},
series = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
Umwelt / Energy $\&$ Environment},
pages = {VIII, 98 S.},
year = {2018},
note = {Universität Duisburg, Diss., 2017},
abstract = {Cerium oxide is a rare earth metal oxide with versatile
catalytic properties used for many industrial applications.
The catalytic behavior of cerium oxide is based on its
ability to store and release oxygen by reversibly changing
its oxidation state between Ce$^{4+}$ and Ce$^{3+}$. The
topic of this thesis is the examination of epitaxial,
micrometer-sized, a few monolayers thick cerium oxide
islands with (111) and(100) crystal surface terminations,
prepared on copper single crystalline substrates. These
cerium oxide islands serve as model systems for catalytic
oxidation and reduction reactions. The formation of
CeO$_{2}$ islands of both surface orientations and their
different reduction behaviors were observed simultaneously,
in-situ, in real-time and under identical conditions with
low energy and photoemission electron microscopy and X-ray
absorption spectroscopy. Experiments on the reduction
behavior of CeO$_{2}$ (111) and (100) oriented islands were
performed using two different approaches: the reduction in a
hydrogen atmosphere and the reduction by deposition of
metallic cerium in vacuum on top of the originally prepared
islands. It was found that the (100) oriented islands became
more reduced than the (111) islands in both cases. Analyzing
the reduction kinetics of the cerium oxide reduction in
hydrogen showed an overall higher reducibillity of the (100)
terminated cerium oxide surface, which is not caused by a
difference in kinetics between the two surface terminations
but by a difference in thermodynamics. This demonstrates
that the surface orientation of cerium oxide has a strong
effect on its catalytic properties, which is in agreement
with predictions by density functional theory calculations.
A reduction experiment in hydrogen atmosphere was also
performed on a platinum/cerium oxide system, which was
prepared by the deposition of Pt on top of CeO$_{2}$ (111)
and (100) islands. The observed formation of highly reduced
cerium oxide structures decorating the original islands
indicated a mixture of platinum and cerium oxide and the
formation of active centers for catalysis in these areas.
For the (100) islands, the formation of the highly reduced
structures was observed to a greater degree, again showing a
behavioral difference between the two cerium oxide surface
orientations.},
cin = {PGI-6},
cid = {I:(DE-Juel1)PGI-6-20110106},
pnm = {899 - ohne Topic (POF3-899)},
pid = {G:(DE-HGF)POF3-899},
typ = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
url = {https://juser.fz-juelich.de/record/844540},
}