Gas Diffusion Layers (GDLs) must have good electrical conductivity and a great hydrophobicity to prevent the pore flooding. These properties can be enhanced by adding a Micro Porous Layer (MPL) based on carbon composites. In this work several MPLs were prepared using carbon-based fillers, such as exfoliated graphite, carbon black and nanotubes, incorporated at very low loadings (<1% wt) in a porous PVDF based matrix obtained by the phase separation technique. The samples were characterized by measurements of electrical resistance, gas permeability and contact angle as well as observations with both optical and field emission electron microscopy.
Carbon black has given overall interesting results as it can be well dispersed in the polymeric matrix and can improve all the fundamental properties required for an MPL.
Exfoliated graphite showed an interesting decrease of the electrical conductivity only after compression of the MPL, probably due to its two-dimensional structure. Nanotubes showed a strong tendency to agglomeration, so the final properties mainly depend on the homogeneity of the dispersion of these aggregates.