Impedance Characterization of a Model Au/Yttria-Stabilized Zirconia (YSZ)/Au Electrochemical Cell in Varying Oxygen and NOx Concentrations
An electrochemical cell (Au/YSZ/Au) serves as a model system to investigate the effect of O{sub 2} and NO{sub x}. 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 NO{sub x} response. Impedance data were obtained over a range of frequencies (0.1 Hz to 1 MHz), temperatures (600 to 700 C), and oxygen (2 to 18.9%) and NO{sub x} (10 to 100 ppm) concentrations. Spectra were fit with an equivalent circuit, and values of the circuit elements were evaluated. In the absence of NO{sub x}, the effect of O{sub 2} 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 O{sub 2} concentrations. When both O{sub 2} and NO{sub x} 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 impedance metric NO{sub x} sensing are also discussed.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 902339
- Report Number(s):
- UCRL-JRNL-225792; JESOAN; TRN: US200717%%262
- Journal Information:
- Journal of the Electrochemical Society, Vol. 154, Issue 4; ISSN 0013-4651
- Country of Publication:
- United States
- Language:
- English
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