Oxygen- and proton-transporting open framework ionomer for medium-temperature fuel cells

Medium-temperature proton exchange membrane fuel cells (MT PEMFCs) operating at 100° to 120°C have improved kinetics, simplified thermal and water management, and broadened fuel tolerance compared with low-temperature PEMFCs. However, high temperatures lead to Nafion ionomer dehydration and exacerbate gas transportation limitations. Inspired by osmolytes found in hyperthermophiles, we developed α-aminoketone–linked covalent organic framework (COF) ionomers, interwoven with Nafion, to act as “breathable” proton conductors. This approach leverages synergistic hydrogen bonding to retain water, enhancing hydration and proton transport while reducing oxygen transport resistance. For commercial Pt/C, the MT PEMFCs…