Enhanced Proton Conductivity of Sulfonated Polysulfone Membranes under Low Humidity via the Incorporation of Multifunctional Graphene Oxide

Abstract

Development of proton exchange membranes with sufficiently high proton conductivity, especially at low relative humidity (RH), remains a big challenge in the field of fuel cells. In this study, graphene oxide-based nanoscale ionic materials (NIMs-GO) were prepared by sulfonation with 3-(trihydroxysilyl)-1-propane­sulfonic acid and subsequent neutralization with amino-terminated polyoxypropylene (PO)–polyoxyethylene (EO) block copolymer. The resultant NIMs-GO with acid–base pairs and hygroscopic EO units were incorporated into sulfonated polysulfone (SPSF) to fabricate nanocomposite membranes. A matrix-softening phenomenon was found due to the extensive interaction between the SPSF matrix and the amphiphilic NIMs-GO, which primarily contributes to the homogeneous dispersion of the NIMs-GO filler in the nanocomposite membranes. The acid–base pairs and the interconnected hydrogen-bonded networks formed between the EO units and water molecules imparted efficient proton transfer via the Grotthuss mechanism. The water uptake and retention ability of the SPSF/NIMs-GO nanocomposite membranes were enhanced due to the hydrophilic EO units on NIMs-GO. As a result, the nanocomposite membrane exhibited a 52% increase compared with the pristine SPSF membrane in proton conductivity at 75 °C, 100% RH and a 24-fold increase at 75 °C, 40% RH. This enhanced proton conductivity led to an elevated fuel cell performance under both hydrous and low RH conditions.

Novel polysulfone/sulfonated polyaniline/niobium pentoxide polymer blend nanocomposite membranes for fuel cell applications

“…It also exhibits moderate reactivity in aromatic electrophilic substitutions and biocompatibility. [36][37][38][39][40] Polysulfone/polyaniline-poly(vinyl pyrrolidone) (PANI-PVP) nanocomposite facilitate water diffusion into the membrane pore and enhanced the hydrophilicity. 41 Polyaniline blended with polysulfone prepared by solution casting method exhibited moderately enhanced water hydrophilicity and used as a promising candidate for water filtration membrane.…”

“…Polysulfone (PSU) is an interesting aromatic polymer that possesses good physicochemical properties with excellent thermal and oxidative stabilities. It also exhibits moderate reactivity in aromatic electrophilic substitutions and biocompatibility 36–40 …”

Investigation of Sulfonated Graphene Oxide as the Base Material for Novel Proton Exchange Membranes

“…The SGO-2.5 results were superimposable to the ones of Nafion ® 212. One should notice that the extrapolated values for the commercial material were larger than the typical results reported in the literature, which were about 0.1 S cm −1 [ 1 , 51 , 52 , 53 ]. Such an inconsistency could be ascribed to the condensation of water droplets on the surface of the stainless-steel electrodes during the tests, which could have altered the final measurements.…”

Recent Advancements in Polysulfone Based Membranes for Fuel Cell (PEMFCs, DMFCs and AMFCs) Applications: A Critical Review

“…In addition, the obtained PEMFCs results were much better than the commercially existing Nafion ® 117 membranes. Jinzhao Li et al reported graphene oxide-based nanoscale ionic materials (NIMs-GO) by sulfonation with 3-(trihydroxysilyl)-1-propanesulfonic acid (SIT) and consequent neutralization with amino-terminated poly-oxypropylene (PO)-polyoxyethylene (EO) block co-polymer [70]. The schematic illustration of the NIMs-GO synthesis is depicted in Figure 5(A1).…”