Tailoring Proton Conductivity and Stability Via Graphene Oxide Incorporation in Phosphoric Acid-Doped Poly(triazine triamine–diphenol diacetol) Membranes

Aromatic polymers have gathered much interest as promising candidates for membranes in fuel cell applications due to providing multiple sites for electrophilic substitution with the SO 3 H group. However, free radical attacks during proton exchange membrane fuel cell operation primarily cause degradation, reducing proton conductivity. To mitigate these challenges, we prepared phosphoric acid (PA)-incorporated triazine-triamine-based diphenyl diacetol (TT-DPDA) polymers with graphene oxide (GO) functionalization and utilized as a membrane for fuel cell applications. The resulting electrolyte nanocomposite membrane, comprised of functionalized GO nanosheets integrated into the PA/TT-DPDA (GO@PA/TT-DPDA) polymer matrix exhibited a marked increase in the proton conductivity. Notably, the membrane containing 3% GO demonstrated an impressive ion exchange capacity of 1.27 mol –1 g –1 and a proton conductivity of 11 × 10 –2 S/cm at 120 °C. Analysis of the proton transport mechanisms within the membrane, based on Arrhenius plots for proton conductivity, indicated that both Grotthuss and vehicular mechanisms contribute to effective proton conduction. Furthermore, the 3% GO-dispersed PA/TT-DPDA polymer nanocomposite membrane exhibited a remarkable oxidative stability, registering a value of 50.2% in Fenton solution at 80 °C over 24 h. The mechanical properties of both the PA/TT-DPDA polymer and its GO-enhanced counterpart were rigorously evaluated, highlighting the potential of these membranes for applications in fuel cell technologies.