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Oxidation kinetics of La and Yb incorporated Zr-doped ceria for solar thermochemical fuel production in the context of dopant ionic radius and valence

Lee, Kangjae and Knoblauch, Nicole and Agrafiotis, Christos and Pein, Mathias and Roeb, Martin and Sattler, Christian (2022) Oxidation kinetics of La and Yb incorporated Zr-doped ceria for solar thermochemical fuel production in the context of dopant ionic radius and valence. Open Ceramics. Elsevier. doi: 10.1016/j.oceram.2022.100269. ISSN 2666-5395.

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Abstract

The influence of ionic radii and valence of dopants in Ce0.9LaxYbyZr0.1-x-yO2-d (x = 0, 0.05, 0.1, y = 0, 0.05, 0.1) on the oxidation kinetics were investigated by thermogravimetric analysis in synthetic air and were compared to undoped ceria. Samples co-doped with Zr-La and Zr-Yb exhibited moderate oxidation kinetics that were slower than undoped ceria, but much faster than 10mol% Zr-doped ceria. The extrinsic oxygen vacancy induced by the trivalent dopants improves the kinetics at oxidation temperatures below 700 °C, where the diffusion, and not the surface exchange reaction is the limiting factor. A smaller ionic radius of the substituent (i.e. r(Yb3+) r(La3+)) in the co-doped ceria tends to facilitate lower activation energy resulting in slightly faster oxidation kinetics at temperatures below 700 °C. In contrast, additional extrinsic vacancies are rather obstructive at high temperatures (i.e. T 700 °C) due to a change of rate limiting mechanism from bulk oxygen diffusion to surface exchange reaction. Overall, the valence of the dopant rather than the ionic radius seems to determine the oxidation kinetics primarily, and additional La or Yb doping on Zr-doped ceria is appealing especially when the applications are focused on low temperature reactions.

Item URL in elib:https://elib.dlr.de/192333/
Document Type:Article
Title:Oxidation kinetics of La and Yb incorporated Zr-doped ceria for solar thermochemical fuel production in the context of dopant ionic radius and valence
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Lee, KangjaeUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Knoblauch, NicoleUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Agrafiotis, ChristosUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Pein, MathiasUNSPECIFIEDhttps://orcid.org/0000-0002-2796-1229UNSPECIFIED
Roeb, MartinUNSPECIFIEDUNSPECIFIEDUNSPECIFIED
Sattler, ChristianUNSPECIFIEDhttps://orcid.org/0000-0002-4314-1124UNSPECIFIED
Date:June 2022
Journal or Publication Title:Open Ceramics
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
DOI:10.1016/j.oceram.2022.100269
Publisher:Elsevier
ISSN:2666-5395
Status:Published
Keywords:Doped ceriaThermochemical redox cyclingThermogravimetric analysisOxidation kineticsIonic radii valence
HGF - Research field:Energy
HGF - Program:Materials and Technologies for the Energy Transition
HGF - Program Themes:Chemical Energy Carriers
DLR - Research area:Energy
DLR - Program:E SW - Solar and Wind Energy
DLR - Research theme (Project):E - Solar Fuels
Location: Köln-Porz
Institutes and Institutions:Institute of Future Fuels > Solar-Chemical Process Development
Institute of Materials Research > Structural and Functional ceramics
Deposited By: Knoblauch, Nicole
Deposited On:14 Dec 2022 10:09
Last Modified:17 Oct 2023 04:14

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