Porous layered oxide/Nafion® nanocomposite membranes for direct methanol fuel cell applications

Nanocomposite membranes were prepared by exfoliating, intercalating and/or dispersing nanoporous layered aluminophosphate or silicate materials in Nafion®. Specifically, the layered aluminophosphate-triethylamine (APO-TE), aluminophosphate-isopropanolamine (APO-IPA), aluminophosphate-imidazole (APO-ImH), and the swollen layered silicate AMH-3, were used as selectively permeable barriers that can potentially block methanol permeation but maintain proton conductivity in the membrane. The presence of the layered materials in Nafion® membranes reduced the methanol permeability by up to an order of magnitude while maintaining proton conductivities close to that of neat Nafion® at room temperature. Small-angle X-ray scattering (SAXS) characterization shows substantial differences in microstructure of the nanocomposite membranes from that of neat Nafion®. The performance of the nanocomposite membranes was also found to be strongly dependent on the membrane pre-treatment conditions. Detailed comparison of our data to the previous literature indicates that for certain conditions of membrane preparation, the proposed approach yields promising results in controlling methanol and proton transport through membranes for direct methanol fuel cell (DMFC) applications.