Impedance Characterization of a Model Au/Yttria-Stabilized Zirconia/Au Electrochemical Cell in Varying Oxygen and NOx Concentrations

Loading...
Thumbnail Image
Penn collection
Departmental Papers (CBE)
Degree type
Discipline
Subject
Funder
Grant number
License
Copyright date
Distributor
Related resources
Author
Woo, Leta Y
Martin, L. Peter
Glass, Robert S
Contributor
Abstract

An electrochemical cell [Au/yttria-stabilized zirconia (YSZ)/Au] serves as a model system to investigate the effect of O2 and NOx. Possible mechanisms responsible for the response are presented. Two dense Au electrodes are co-located on the same side of a dense YSZ electrolyte and are separated from the electrolyte by a porous YSZ layer, present only under the electrodes. While not completely understood, the porous layer appears to result in enhanced NOx response. Impedance data were obtained over a range of frequencies 0.1 Hz to 1 MHz, temperatures 600–700°C, and oxygen 2–18.9% and NOx 10–100 ppm concentrations. Spectra were fit with an equivalent circuit, and values of the circuit elements were evaluated. In the absence of NOx, the effect of O2 on the low-frequency arc resistance could be described by a power law, and the temperature dependence by a single apparent activation energy at all O2 concentrations. When both O2 and NOx were present, however, the power-law exponent varied as a function of both temperature and concentration, and the apparent activation energy also showed dual dependence. Adsorption mechanisms are discussed as possibilities for the rate-limiting steps. Implications for impedancemetric NOx sensing are also discussed.

Advisor
Date Range for Data Collection (Start Date)
Date Range for Data Collection (End Date)
Digital Object Identifier
Series name and number
Publication date
2007-02-15
Journal title
Volume number
Issue number
Publisher
Publisher DOI
Journal Issue
Comments
© The Electrochemical Society, Inc. 2007. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in Journal of the Electrochemical Society, Volume 154, Issue 4, February 2007, pages J129-135. Publisher URL: http://dx.doi.org/10.1149/1.2456328
Recommended citation
Collection