Uncovering Alternate Pathways to Nafion Membrane Degradation in Fuel Cells with First-Principles Modeling

• DOI: 10.1021/acs.jpcc.0c04417
• Publication Date: 2020-06-23T03:47:10Z
• Authors: Akash Bajaj; Fang Liu; Heather J. Kulik
• Keywords: Nafion; Degradation; Sulfonic acid

Polymer electrolyte membrane fuel cells (PEMFCs) represent promising energy storage solutions, but challenges remain to maximize their utility. Nafion is frequently employed as the PEMFC material, degradation of can limit life PEMFCs. Using hybrid density functional theory (DFT), we carry out reaction pathway analysis on a range candidate pathways both pristine and defect-containing models Nafion. Degradation initiated by hydrogen radicals involves moderate (ca. 20 kcal/mol) barriers lower than alternative hydroxyl radicals. We propose new for continued after initial H radical attack in presence H2O2. This has modest barrier provides mechanistic basis production experimentally observed trifluoroacetic acid fluoride. Our work suggests inherent limits studies that use sole source model under operating conditions. observe hydroxyl-radical-only mechanisms have competitive with species only initiation at carboxylic defects main chain or sulfonic groups side chain. confirm our observations DFT comparison correlated wave function theory. study highlights importance thorough first-principles modeling identify most probable, low-energy materials degradation.