DSC/DVS investigation of water mobility in nafion/zeolite composite membranes for fuel cell applications

Nafion/Faujasite zeolite composite membranes have been prepared by solution casting at a zeolite content ranging from 0.98 to 21.4 wt %. The effect of the zeolite loading on the mobility of both liquid and vapor water through the Nafion membrane has been investigated by using two complementary techniques, that is, differential scanning calorimetry and dynamic vapor sorption. The relationship between water mobility, proton conductivity, and direct methanol fuel cell (DMFC) performance of composites is also discussed. The addition of zeolite contributes to the enhancement of the water mobility degree in the composite membrane due to both the surface composition of the additive and the introduction of porosity at the polymer/filler interface. Nafion/zeolite composites having higher proton conductivity and DMFC performance than bare Nafion can thus be fabricated by fine-tuning of the additive content and the membrane morphology.