Fig. 5: Humidity–conductivity relationship of TpPa-SO3H, TpBD-(SO3H)2 iCOFMs, and Nafion 212 membrane.
From: Assembling covalent organic framework membranes with superior ion exchange capacity

a Proton conductivity of the TpPa-SO3H, TpBD-(SO3H)2 iCOFMs, and Nafion 212 membrane versus relative humidity at 40 °C. b Schematic illustration of ion transport channels changes with decreased relative humidity (RH) for the Nafion 212 membrane, TpPa-SO3H and TpBD-(SO3H)2 iCOFMs, Δ represents the difference in the proton conductivity of the membranes at 100% RH and 40% RH.