Polyelectrolyte Nanocomposite Membranes Using Surface Modified Nanosilica for Fuel Cell Applications

The preparation and characterization of a new type of nanocomposite polyelectrolyte membrane (PEM), based on Nafion (R) (E. I. du Pont de Nemours and Co., Ltd., for its copolymer of tetrafluoroethylene and perfluorinated vinyl ether) and sulfonic acid (-SO3H) or phosphotungstic acid (PWA) modified nanosilica (Si-SO3H or Si-PWA, respectively), for direct methanol fuel cell (DMFC) applications are described. Physical characteristics of these manufactured nanocomposite membranes were investigated by scanning electron microscopy (SEM), water uptake, methanol permeability and ion exchange capacity, as well as proton conductivity. The Nafion (R)/Si-PWA and Nafion (R)/Si-SO3H membranes showed higher proton conductivity, lower methanol permeability and, as a consequence, a higher selectivity parameter, in comparison to the neat Nafion (R) or Nafion (R)/pristine nanosilica membranes. The obtained results indicated that both the Nafion (R)/Si-PWA and Nafion (R)/Si-SO3H membranes could be utilized as promising polyelectrolyte membranes for direct methanol fuel cell applications.