Graphene Oxide–Polymer Nanocomposite Anion-Exchange Membranes

Abstract

Functionalized graphene oxide (FGO) was incorporated into polyvinyl alcohol/ poly(diallyldimethylammonium chloride) semi-interpenetrating polymer networks (PVA/PDA SIPNs) in order to create novel nanocomposite anion-exchange membranes (AEMs) with improved OH− conductivity and good thermo-mechanical stability at high relative humidity. The nanocomposites were fabricated by a solvent-casting method and subsequently thermally crosslinked to improve their mechanical stability in the hydrated state. The effects of PVA/PDDA ratio, cross-linking method, cross-linking temperature, and FGO content were studied in order to determine the optimal conditions to fabricate AEMs with improved material properties. The membranes were characterized by XRD, FTIR, TGA, FE-SEM, and impedance spectroscopy to assess the material properties of FGO and the nanocomposite membranes. The membranes were also evaluated as polymer electrolytes in anion exchange membrane fuel cells. The results reveal that the membrane fabricated at a PVA/PDDA weight ratio of 70/30 and 20 wt% FGO possesses the highest value of OH− conductivity (12.1 mS cm−1 @ 30°C and 21 mS cm−1 @ 80°C), as well as improved thermo-mechanical stability at 100% R.H. However, the fuel cell performance reaches a maximum using the membrane fabricated at 10 wt% FGO.