Graphene oxide incorporated PSU/SPEKEKK for potential application as proton exchange membranes in fuel cells

This study aims to develop a new PEM for fuel cell applications consisting of PSU/SPEKEKK/SGO membranes with improved physiochemical properties to surmount the low power generation of Nafion. The DFT calculations using NCI plots show that there are network interactions between PSU and SPEKEKK, established by the hydrogen bonding and vdW interactions. SGO was incorporated into the as-prepared PSU/SPEKEKK membrane. A solution casting method was employed to fabricate SGO-loaded composite membranes in the range of 0.1% to 1.5% (wt%). Structural evidence of the SGO and composite membranes was characterized by ATR-FTIR and FESEM, respectively. Adding SGO to PSU/SPEKEKK shows a significant increase in proton conductivity due to the presence of more protonated sites (SO₃H) and water-mediated interactions for proton conduction. Of all the compositions considered, PSU/SPEKEKK/SGO-0.6-1.5% loading was found to have the highest proton conductivity, 0.03Scm⁻¹. Although adding SGO to the composite membrane has reduced water absorption, the hydrophilic oxygenated functional groups in SGO, the bound water molecules, and the increased –SO₃H groups have successfully improved the proton conductivity. The findings reveal that all composite membranes show excellent oxidative stabilities for 32 h in Fenton's reagent. To summarize, all composite membranes fabricated in this study show acceptable water uptake and swelling ratio, high oxidation, excellent thermal stability, and high proton conductivity.