Sulfonated graphene oxide–silica for highly selective Nafion-based proton exchange membranes

Abstract

In the current study, sulfonated graphene oxide-silica (S-GO-SiO 2 ) nanohybrid particles were obtained first. The FTIR, TGA, XRD, Raman, AFM, FE-SEM and EDX characterizations were employed to confirm the successful decoration of SiO 2 onto GO surface and the attachment of sulfonic acid groups onto the GO-SiO 2 surface. Then, S-GO-SiO 2 /Nafion proton exchange membranes (PEMs) were prepared via solution casting. S-GO-SiO 2 had a good dispersibility inside the membrane matrix. The increased water uptake and the incorporated -SO 3 H groups bestowed a large increase in proton conductivity upon these composite PEMs. Meanwhile, the barrier effect of two-dimensional S-GO-SiO 2 contributed to the obvious reduction in methanol permeability of the composite PEMs, as a result of the increased tortuosity of the transport channels. Therefore, novel S-GO-SiO 2 /Nafion PEMs with enhanced selectivity (the ratio of proton conductivity to methanol permeability) were obtained. Even under harsh conditions, such as high methanol concentration and/or increased temperature, the membrane selectivity of S-GO-SiO 2 /Nafion composite membranes was still nearly two-orders-of-magnitude higher than that of the recast Nafion membrane. It renders this type of composite PEMs a very promising candidate for the application in DMFC. All the conclusions were demonstrated by various characterizations, such as (FE-) SEM, TEM, AFM, FTIR, TGA, water uptake, etc.

Does thermal treatment merely make a H2O-saturated Nafion membrane lose its absorbed water at high temperature?

“…6,22 First, most of the solvent of the as-received Nafion solution was replaced by dimethylformamide (DMF). 6,22 First, most of the solvent of the as-received Nafion solution was replaced by dimethylformamide (DMF).…”

“…5 Until now, researchers have explored various physical and chemical approaches to modify PEMs, attempting to make PEMs meet the standard for real-world applications. 22 Nafion, for example, is one of the most investigated PEM materials. 18,19 An ideal PEM must have high proton conductivity even under severe operation conditions.…”

Direct polymerization of a novel sulfonated poly(arylene ether ketone sulfone)/sulfonated poly(vinylalcohol) crosslinked membrane for direct methanol fuel cell applications

“…Direct methanol fuel cells (DMFCs) have attracted much interest, due to their advantages of inexpensive raw materials, high energy conversion efficiency, and low operating temperature [1,2]. The transportation of methanol fuel is more convenient than that of hydrogen fuel.…”

Effect of degree of sulfonation and casting solvent on sulfonated poly(ether ether ketone) membrane for vanadium redox flow battery

“…Although the state-of-the-art perfluorosulfonic polymer like Nafion membrane is currently utilized as the benchmark owing to its high proton conductivity and outstanding stability, the markedly high vanadium ion permeability of Nafion membrane indeed restricts its further usage in VRFB [13,14]. Despite considerable modifications of pristine Nafion membrane show better VRFB performance, the virtually high cost of Nafion membrane is still unfavourable for the VRFB commercialization [15e18].…”