Sulfonated polyether (ether) ketone (sPEEK) membranes (repeating unit displayed) are an environmentally friendly candidate for membranes for polymer electrolyte membrane fuel cells. Radical OH molecules are present in the process of a fuel cell’s operation and may react with sPEEK to degrade the membrane. It has been suggested that the main decomposition reaction is addition of OH radical to sPEEK, followed by acid-catalyzed water elimination to leave an unstable cation, which then degrades. Our recent computational work investigates this mechanism as well as another addition-elimination mechanism, suggested by a recent density functional study of the reaction of sPEEK with H radicals, in which OH adds add to sPEEK and bond-breaking degradation reactions immediately follow. Results suggest that both reactions are exothermic and thermodynamically favorable with comparable barriers, and that it is likely that both mechanisms occur in fuel cells and contribute to its degradation

Density functional study of the reactions of OH radicals with sPEEK fuel cell membranes

ACS Spring Meeting 2021

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