The Chemical Behavior and Degradation Mitigation Effect of Cerium Oxide Nanoparticles in Perfluorosulfonic Acid Polymer Electrolyte Membranes

Journal Article · Tue Jan 01 04:00:00 EST 2013 · Polymer Degradation and Stability

DOI:https://doi.org/10.1016/j.polymdegradstab.2013.05.025· OSTI ID:1095704

Pearman, Benjamin P ^[1]; Mohajeri, Nahid ^[1]; Slattery, Darlene ^[2]; Hampton, Michael ^[3]; Seal, Sudipta ^[4]; Cullen, David A ^[1]

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1. ORNL
2. Florida Solar Energy Center (FSEC)
3. University of Florida
4. University of Central Florida

Perfluorosulfonic acid membranes, the polymer of choice for polymer electrolyte hydrogen fuel cells, are susceptible to degradation due to attacks on polymer chains from radicals. Mitigation of this attack by cerium-based radical scavengers is an approach that has shown promise. In this work, two formulations of single-crystal cerium oxide nanoparticles, with an order of magnitude difference in particle size, are incorporated into said membranes and subjected to proton conductivity measurements and ex-situ durability tests. We found that ceria is reduced to Ce(III) ions in the acidic environment of a heated, humidified membrane which negatively impacts proton conductivity. In liquid and gas Fenton testing, fluoride emission is reduced by an order of magnitude, drastically increasing membrane longevity. Side-product analysis demonstrated that in the liquid Fenton test, the main point of attack are weak polymer end groups, while in the gas Fenton test, there is additional side-chain attack. Both mechanisms are mitigated by the addition of the ceria nanoparticles, whereby the extent of the durability improvement is found to be independent of particle size.

• Research Organization: Oak Ridge National Laboratory (ORNL); Shared Research Equipment Collaborative Research Center
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1095704
• Journal Information: Polymer Degradation and Stability, Journal Name: Polymer Degradation and Stability Journal Issue: 9 Vol. 98; ISSN 0141-3910
• Publisher: Elsevier
• Country of Publication: United States
• Language: English