Covalent grafting of polystyrene sulfonic acid on graphene oxide nanoplatelets to form a composite membrane electrolyte with sulfonated poly(ether ether ketone) for direct methanol fuel cells

Covalent grafting of polystyrene sulfonic acid (PSSA) on graphene oxide nanoplatelets (GONP) via in situ radical polymerization was conducted. PSSA-g-GONP is used as an additive to form a nanocomposite membrane with sulfonated poly(ether ether ketone) (sPEEK) for its application in direct methanol fuel cells (DMFCs), with better physicochemical properties and reduced methanol crossover compared to that of pristine sPEEK. The optimized sPEEK/PSSA-g-GONP (0.15 wt %) nanocomposite membrane exhibits a DMFC peak power density of 170 mW cm-2, which is 50 % greater than the 110 mW cm-2 for pristine sPEEK and one-fold greater than that of 80 mW cm-2 observed for commercial Nafion® 117 due to its high electrochemical selectivity. Furthermore, the nanocomposite membrane shows better durability up to 100 h compared with sPEEK and Nafion® 117 electrolyte membranes, demonstrating its potential in diverse membrane applications. sPEEK/PSSA-g-GONP membrane shows higher direct methanol fuel cell power output with reduction in methanol crossover compared to sPEEK and Nafion. [Display omitted] •Grafting of polystyrene sulfonic acid on graphene oxide nanoplatelets (PSSA-g-GONP)•sPEEK/PSSA-g-GONP (0.15 wt %) membranes show enhanced physico-chemical properties.•Nanocomposite membranes show 40 % reduction in methanol crossover compared to sPEEK.•sPEEK/PSSA-g-GONP shows 50 % enhanced direct methanol fuel cell (DMFC) performance.•sPEEK/PSSA-g-GONP shows one fold higher DMFC performance compared to Nafion®.