Highly selective sulfonated Poly (arylene ether nitrile) composite membranes containing copper phthalocyanine grafted graphene oxide for direct methanol fuel cell

Abstract

To improve the performances of sulfonated poly (arylene ether nitrile) (SPEN)–based proton exchange membranes (PEMs) in direct methanol fuel cells (DMFCs), the copper phthalocyanine grafted graphene oxide (CP-GO) was successfully prepared via in situ polymerization and subsequently incorporated into SPEN as filler to fabricate a series of SPEN/CP-GO-X (X represents for the mass ratio of CP-GO) composite membranes. The water absorption, swelling ratio, mechanical properties, proton conductivity, and methanol permeability of the membranes were systematically studied. CP-GO possesses good dispersion and compatibility with SPEN matrix, which is propitious to the formation of strong interfacial interactions with the SPEN, so as to provide more efficient transport channels for proton transfer in the composite membranes and significantly improve the proton conductivity of the membranes. Besides, the strong π–π conjugation interactions between CP-GO and SPEN matrix can make the composite membranes more compact, blocking the methanol transfer in the membranes, and significantly reducing the methanol permeability. Consequently, the SPEN/CP-GO-1 composite membrane displayed outstanding tensile strength (58 MPa at 100% RH and 25^°C), excellent proton conductivity (0.178 S cm⁻¹ at 60°C), and superior selectivity (5.552 × 10⁵ S·cm⁻³·s). This study proposed a new method and strategy for the preparation of high performance PEMs.