This title appears in the Scientific Report :
2018
Please use the identifier:
http://hdl.handle.net/2128/17935 in citations.
Reduction properties of a model ceria catalyst at the microscopic scale
Reduction properties of a model ceria catalyst at the microscopic scale
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...
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Personal Name(s): | Hackl, Johanna Maria (Corresponding author) |
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Contributing Institute: |
Elektronische Eigenschaften; PGI-6 |
Imprint: |
Jülich
Forschungszentrum Jülich GmbH Zenralbibliothek, Verlag
2018
|
Physical Description: |
VIII, 98 S. |
Dissertation Note: |
Universität Duisburg, Diss., 2017 |
ISBN: |
978-3-95806-294-8 |
Document Type: |
Book Dissertation / PhD Thesis |
Research Program: |
ohne Topic |
Series Title: |
Schriften des Forschungszentrums Jülich Reihe Energie & Umwelt / Energy & Environment
407 |
Link: |
OpenAccess OpenAccess |
Publikationsportal JuSER |
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. |