1 research outputs found
Sulfonated Graphene Oxide Platelets in Nafion Nanocomposite Membrane: Advantages for Application in Direct Methanol Fuel Cells
Graphene oxide (GO) is well known
as an excellent amphiphilic material due to its oxygen-containing
functional groups and its chemical tunability. By intercalation chemistry,
organo-modified GO containing sulfonilic terminal groups were prepared
and used as nanoadditive in Nafion polymer for the creation of hybrid
exfoliated composites. The incorporation of hydrophilic 2D platelike
layers in the Nafion membranes is expected to induce advantages in
terms of thermal stability and mechanical and barrier properties (limitation
of the methanol crossover by increased tortuosity and obstruction
effect), although it may negatively affect the proton conductivity.
In this work, we show how different preparation methods of the nanocomposites
influence morphology, transport properties, and barrier effect to
methanol. The hybrid membranes are characterized by powder X-ray diffraction
and microscopies (SEM, TEM, and AFM). Water and methanol transport
properties inside the nanocomposites are investigated by NMR spectroscopy
(diffusivity and relaxation times), unveiling a reduction of the methanol
diffusion and, nevertheless, an increase in the proton mobility and
water retention at high temperatures. Finally, the electrochemical
properties are investigated by direct methanol fuel cell (DMFC) tests,
showing a significant reduction of the ohmic losses at high temperatures,
extending in this way the operating range of a DMFC