Facile tailor-made enhancement in proton conductivity of sulfonated poly(ether ether ketone) by graphene oxide nanosheet for polymer electrolyte membrane fuel cell applications

Sulfonated poly(ether ether ketone) and graphene oxide nanocomposite-based polymer electrolyte membranes were prepared by facile solution casting method, and their applications for single cell were investigated. The degree of sulfonation played an important role in the proton conductivity of polymer electrolytes. Thus, we studied both the low and high degree of sulfonated poly ether ether ketones (SPEEKs) as composite with amphiphilic graphene oxide nanosheets (GNSs). The obtained results on water uptake and swelling profile showed that the physical and chemical properties of polymer electrolytes significantly improved after insertion of GNS. Morphological properties of the fabricated membranes were investigated with field emission scanning electron microscopy (FE-SEM), and the equal dispersion of GNS sheets throughout the cross section of polymer matrix was observed. The temperature-dependent conductivity reveals that SPEEK-GNS composite showed improved proton conductivity compared to pure SPEEK, because of the high degree of dispersion of GNS thus facilitated the extension of proton transport channels. Best enhancement in conductivity is observed for composite membrane containing 1.0 wt% of GNS, i.e., 149 mS cm⁻¹.