Fullerene composite proton conducting membranes for polymer electrolyte fuel cells operating under low humidity conditions

Fullerene composite membranes have been prepared by doping Nafion® 117 with fullerenes to fabricate proton conducting composite membranes. The fullerenes used for the composites included C60 and polyhydroxy fullerene, C60(OH)n (n ∼ 12). We report the preparation and the characterization of the composites. ac impedance measurements have indicated that the fullerene–Nafion® composite membranes have higher proton conductivities at both 20 and 80 °C than Nafion® 117, especially under low relative humidity, <50% RH. It has been found from water uptake measurements under 25% relative humidity that the fullerene–Nafion® composite held more water than Nafion® 117 under low humidity. Molecular modeling of the fullerenes support the experimental observations.