Synergistic coupling between ionomers and solid acids for modulating the superproton conductivity in composites

Abstract

We present a truly synergistic proton conductor composite material based on the addition of solid acids to ionomers. A method for fabricating an interpenetrating network of cesium hydrogen sulfate (CHS) into Nafion ionic domains was developed. The compatibility of the sulfate ions as well as cesium and proton counterions of both phases resulted in a structure in which the Nafion side chains were anchored into CHS phase resulting in a composite material with unique properties. Nafion side chain dynamics were affected by the CHS phase, whereas the CHS lattice parameter was disturbed by the interaction with the polymer side chains. Nafion-CHS composites exhibited a threefold increase in the magnitude of the proton conductivity as compared to that of Nafion in anhydrous condition.