Long-term stability of nanostructured thin film electrodes at operating potentials [electronic resource].
- Washington, D.C. : United States. Office of the Assistant Secretary of Energy Efficiency and Renewable Energy, 2017.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
- Physical Description:
- pages F306-F320 : digital, PDF file
- Additional Creators:
- Oak Ridge National Laboratory
United States. Office of the Assistant Secretary of Energy Efficiency and Renewable Energy
United States. Department of Energy. Office of Scientific and Technical Information
- Long-term stability of nanostructured thin film (NSTF) catalysts at operating potentials has been investigated. Compared to high surface area Pt/C catalysts, NSTF electrodes show 20–50x smaller F<sup>–</sup> emission rates (FER) because of their high specific activity for oxygen reduction reaction (ORR), but are susceptible to poisoning by the products of membrane degradation because of their low electrochemically active surface area (ECSA). The observed voltage degradation rates at potentials corresponding to 1–1.5 A/cm<sup>2</sup> current density are much higher than the allowable 13–14 μV/h. Although F<sup>–</sup> is not itself responsible for performance decay, cumulative fluoride release (CFR) is a good marker for catalyst surface contamination. The observed performance decay is not only due to loss of active Pt sites but also adsorbed impurities impeding ORR kinetics. There is a strong correlation between measured CFR and observed decrease in specific ORR activity and limiting current density and increase in mass transfer overpotentials. Furthermore, the correlations indicate that the target of <10% lifetime performance degradation can be achieved by restricting CFR in NSTF electrodes to 0.7 μg/cm<sup>2</sup>, as may be possible with more stable membranes, higher surface area NSTF catalysts, and cell operation at lower temperatures and higher relative humidities.
- Published through SciTech Connect.
Journal of the Electrochemical Society 164 4 ISSN 0013-4651 AM
Rajesh K. Ahluwalia; J. -K. Peng; X. Wang; David A. Cullen; Andrew J. Steinbach.
- Funding Information:
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