M. Di Virgilio, A. Basso Peressut, S. Latorrata, M. Mariani, G. Dotelli
Solid State Ionics, 376 (2022), 115858
https://doi.org/10.1016/j.ssi.2022.115858
Novel self-assembling naphthalene sulfonate-functionalized graphene oxide membranes have been prepared and studied as a possible alternative to conventional perfluorinated proton conductors. This study focused on identifying the most appropriate composition and process conditions to perform an effective functionalization, by investigating three graphene oxide-to-naphthalene sulfonate molar ratios and two mixing temperatures. Characterization by thermogravimetric tests, ATR-FTIR, Raman and EDX spectroscopies, XRD and static contact angle assessment aimed to verify the insertion of naphthalene sulfonate molecules and sulfonic acid groups (–SO3H) in the GO framework, while optical and scanning electron microscopies pointed out the good membrane uniformity. The ion exchange capacity (IEC) has been evaluated to demonstrate the ability of the prepared membranes to exchange protons and has allowed, in combination with the other characterizations, to identify the most promising sample for further water uptake (WU) and electrochemical impedance spectroscopy (EIS) tests. Their aim was to observe how the water sorption and proton conductivity of the material depended on different conditions of relative humidity and temperature, deepening the analysis of its possible application as a future electrolyte in alternative energy generators. The mechanical properties of the most promising membrane have been investigated as well in a preliminary fashion, in order to expand the characterization of its behavior.