Improved performance of quaternized poly(arylene ether ketone)s/graphitic carbon nitride nanosheets composite anion exchange membrane for fuel cell applications

Abstract A series of novel nanocomposite anion exchange membranes (QPAEK) were prepared by incorporating graphitic carbon nitride (g-C3N4) nanosheets into chloromethylated poly(arylene ether ketone)s and the following Menshutkin reaction. Fundamental properties of the nanocomposite membranes with various g-C3N4 nanosheets content were investigated systematically. The prepared QPAEK-CN-0.5 membrane with a low ion exchange capacity (IEC) of 1.31 mmol g−1 exhibited an improved ionic conductivity of 34.5 mS cm−1 at 80 °C, because of the hydrogen bonding interactions between alkaline quaternary ammonium groups and amine/imine groups of g-C3N4 nanosheets. It also displayed a low methanol permeability because the triazine units in g-C3N4 nanosheets can block the methanol crossover but allow water molecules and hydroxide ions to transport. In addition, the QPAEK-CN-0.5 membrane exhibited a power density of 49 mW cm−2 at 80 °C under 100% relative humidity. Furthermore, the molecular dynamics simulation method has been carried out to provide additional insightful structure-performance relationships of the nanocomposite membrane. Overall, this study demonstrated that the introduction of g-C3N4 nanosheets is an effective way to enhance the properties of the anion exchange membrane, especially in ionic conductivity, alkaline resistance and methanol permeability due to their special composition and lattice structure.