Sulfonated poly(vinyl alcohol)/graphene oxide composite membranes for proton exchange membrane fuel cells

Different crosslinked composite membranes of Poly(vinyl Alcohol) PVA with sulfosuccinic acid SSA as crosslinking agent and graphene oxide GO were prepared and characterized as a function of the sulfonating degree and GO percentage of each component. The chemical structure of membranes was confirmed by Fourier transform infrared spectroscopy FTIR. The good dispersion of GO into the polymer matrix was verified by scanning transmission microscopy SEM. The proton conductivity of the membranes in fully hydrated state was also investigated by electrochemical impedance spectroscopy EIS. To measure the potential use of PVA membranes as electrolyte were tested in a single proton exchange membrane fuel cell PEMFC. The results reveal that the addition of graphene oxide GO improves the thermal and mechanical stability of the composite membranes. The proton conductivity of the prepared membranes strongly increases by combination of matrix's sulfonating and introduction of GO nanoparticles. Thus, the sulfonating of the polymer matrix in the 30sPVA/SSA/GO membrane increases the proton conductivity a 42% and a 67% of maximum power density respect its homologue 30PVA/SSA membrane. In addition, 30sPVA/SSA/sGO membrane shows the lowest values of proton conductivity and maximum power density, which is consistent with the obtained water uptake values and confirms the improvement of barrier property of these composite membranes.