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A Space-Charge Treatment of the Increased Concentration of Reactive Species at the Surface of a Ceria Solid Solution

Zurhelle, Alexander F. and Tong, Xiaorui and Klein, Andreas and Mebane, David S. and De Souza, Roger A. (2017):
A Space-Charge Treatment of the Increased Concentration of Reactive Species at the Surface of a Ceria Solid Solution.
In: Angewandte Chemie International Edition, Wiley-VCH Verlag GmbH, Weinheim, pp. 14516-14520, 56, (46), ISSN 14337851, DOI: 10.1002/anie.201708118, [Online-Edition: https://doi.org/10.1002/anie.201708118],
[Article]

Abstract

A space‐charge theory applicable to concentrated solid solutions (Poisson–Cahn theory) was applied to describe quantitatively as a function of temperature and oxygen partial pressure published data obtained by in situ X‐ray photoelectron spectroscopy (XPS) for the concentration of Ce3+ (the reactive species) at the surface of the oxide catalyst Ce0.8Sm0.2O1.9. In contrast to previous theoretical treatments, these calculations clearly indicate that the surface is positively charged and compensated by an attendant negative space‐charge zone. The high space‐charge potential that develops at the surface (>0.8 V) is demonstrated to be hardly detectable by XPS measurements because of the short extent of the space‐charge layer. This approach emphasizes the need to take into account defect interactions and to allow deviations from local charge neutrality when considering the surfaces of oxide catalysts.

Item Type: Article
Erschienen: 2017
Creators: Zurhelle, Alexander F. and Tong, Xiaorui and Klein, Andreas and Mebane, David S. and De Souza, Roger A.
Title: A Space-Charge Treatment of the Increased Concentration of Reactive Species at the Surface of a Ceria Solid Solution
Language: English
Abstract:

A space‐charge theory applicable to concentrated solid solutions (Poisson–Cahn theory) was applied to describe quantitatively as a function of temperature and oxygen partial pressure published data obtained by in situ X‐ray photoelectron spectroscopy (XPS) for the concentration of Ce3+ (the reactive species) at the surface of the oxide catalyst Ce0.8Sm0.2O1.9. In contrast to previous theoretical treatments, these calculations clearly indicate that the surface is positively charged and compensated by an attendant negative space‐charge zone. The high space‐charge potential that develops at the surface (>0.8 V) is demonstrated to be hardly detectable by XPS measurements because of the short extent of the space‐charge layer. This approach emphasizes the need to take into account defect interactions and to allow deviations from local charge neutrality when considering the surfaces of oxide catalysts.

Journal or Publication Title: Angewandte Chemie International Edition
Volume: 56
Number: 46
Publisher: Wiley-VCH Verlag GmbH, Weinheim
Uncontrolled Keywords: ceramics, ceria, space–charge theory, surface chemistry, thermodynamics
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Surface Science
Date Deposited: 27 Oct 2017 10:54
DOI: 10.1002/anie.201708118
Official URL: https://doi.org/10.1002/anie.201708118
Funders: he authors acknowledge funding from the Deutsche Forschungsgemeinschaft (DFG): from the collaborative research center SFB 917 “Nanoswitches”; from project SO499/7‐1; and from project KL1225/7‐1.
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