SGO/SPEN-based highly selective polymer electrolyte membranes for direct methanol fuel cells

Abstract

In this study, proton-exchange membranes (PEMs) consisting of sulfonated poly(arylene ether nitrile) (SPEN) have been successfully prepared by incorporating a different amount of sulfonated graphene oxide (SGO). Incorporation of SGO can improve proton conductivity and reduce the methanol permeability. Besides, the existence of the intermolecular interactions between SPEN and SGO can improve the interfacial compatibility between filler and matrix. The resulting composite membranes show better mechanical property, proton conductivity and lower methanol permeability compared to that of pure SPEN. Furthermore, the composite membrane with 1 wt% SGO possesses good interfacial compatibility, exhibiting excellent proton conductivity (0.109 S/cm at 20 °C and 0.265 S/cm at 80 °C) and low methanol permeability (0.17×10−6 cm2·s−1 at 20 °C). So it achieves the highest selectivity (6.412×105 S·s·cm−3), which is about 14 times higher than that of Nafion 117. All these data indicate that the SPEN/SGO composite membranes have good potential for applications in direct methanol fuel cells.