Characterization of (La1-xSrx)(s)MnO3 and Doped Ceria Composite Electrodes in NOx-Containing Atmosphere with Impedance Spectroscopy

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    Abstract

    This study used electrochemical impedance spectroscopy (EIS) to characterize composite metal oxide electrodes in atmospheres containing NO, NO2, and O2. Symmetrical cells with electrodes of (La1−xSrx)sMnO3 [(x, s)=(0.15, 0.9) and (0.5, 0.99)] and doped ceria [Ce0.9Gd0.1O2 and Ce1−xGdxO2 (x=0.1, 0.2)] were subjected to EIS while varying the temperature (from 300 to 600°C), the composition of the atmosphere, and the gas flow. The impedance spectra were fitted to equivalent circuits, and common arcs were identified and sought related to physical and chemical processes. The electrodes had a much lower polarization resistance (Rp) when NO or NO2 was present in the atmosphere at low temperatures (300–400°C) than in air. The impedance spectra for electrodes in 1% NO in Ar were dominated by a low frequency arc at high temperatures (500–600°C). This arc seemed to be a type of conversion arc, which is related to a gaseous intermediate (possibly NO2), formed from NO, through which the electrode reaction occurs. Indications were found that the electrodes are not electrochemically active toward NO around open-circuit voltages. ©2010 The Electrochemical Society
    Original languageEnglish
    JournalJournal of The Electrochemical Society
    Volume157
    Issue number5
    Pages (from-to)P35-P42
    ISSN0013-4651
    DOIs
    Publication statusPublished - 2010

    Bibliographical note

    Copyright The Electrochemical Society, Inc. [2010]. 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).

    Keywords

    • Fuel Cells and Hydrogen
    • Flue gas purification

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