Confinement of functionalized graphene oxide in sulfonated poly (ether ether ketone) nanofibers by coaxial electrospinning for polymer electrolyte membranes

A novel cambiform-like core-shell nanofiber containing sulfonated graphene oxide core is fabricated through coaxial electrospinning method to improve proton conductivity, fuel blocking and inorganics/polymer compatibility for fuel cell applications. As induced by the strong electrostatic force, the sulfonated organosilane functionalized graphene oxide nanosheet is axially elongated to form a unique cambiform-like and highly wrinkled morphology in the core of the sulfonated poly (ether ether ketone) nanofiber, which is evidenced by the transmission electron microscopy images. It provides a forced contact and good dispersion of graphene oxide in the polymer to improve the tensile strength (approximately 2.6 and 1.8 folds of that of the blend monoaxial electrospun and cast membranes, respectively). The wrinkled graphene oxide core contains the sulfonated functional groups and micro-voids which are favorable for water uptake, making the co-spinning membrane exhibit approximately 43.2% and 33.0% increase of water uptake Hydrogen permeation compared with that of the blend monoaxial electrospun and cast membranes, respectively, Fuel cell and thus facilitate the formation of hydrogen bond networks for proton hopping but tortuous pathways for fuel permeation. Accordingly, both lower hydrogen permeation and much higher methanol selectivity (11 folds of that of Nafion 115) are achieved in the co-spinning membrane. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.