Functionalized graphene oxide (FGO) was incorporated into polyvinyl alcohol/ poly(diallyldimethylammonium chloride) semiinterpenetrating 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. Anion exchange membrane fuel cells (AEMFCs) have attracted considerable attention during the last few years due to some advantages that these kinds of systems offer compared to proton exchange membranes fuel cells (PEMFCs).1,2 For example, thanks to the facile kinetics for electrochemical charge transfer in alkaline environments, it is possible to use less expensive catalysts like nickel and silver in AEM-based fuel cells. 3 In terms of the fuel management, it is also possible to use concentrated fuels to operate these devices, because of the often reduced fuel crossover in AEMs. 4 Unfortunately, AEMFCs have some issues, specifically related to the polyelectrolyte performance. In general, AEMs have lower ionic conductivity than PEMs, mostly due to the fact that conductivity of OH − is intrinsically lower than H + . 5 Another concern with the use of AEMs is the degradation of their cationic groups in strong alkaline media. 6 In addition, AEMs usually exhibit poor solubility in low boiling point and inexpensive solvents, leading to less environmentallyfriendly fabrication processes with high costs and high degree of complexity.
7In order to overcome these limitations, a wide variety of membranes have been proposed during the last few decades as AEMs, including homopolymers, heterogeneous membranes and semi-interpenetrating polymer networks (SIPNs). [8][9][10][11] Among the various options available, SIPNs have gained relevance due to ease of fabrication, acceptable ionic conductivities, and excellent mechanical properties.12-14 More specifically, poly(vinyl alcohol)/poly(diallyldimethylammonium chloride) (PVA/PDDA) SIPNs are promising membranes for applications in electrochemical energy systems mainly because PVA is ...
