Manipulating carrier arrangement in lamellar membrane channels towards highly enhanced proton conduction

Abstract

Recent findings highlight the unique superiority of two-dimensional lamellar membranes in ion transport through the well-defined and stable interlayer channels. However, undesired channel chemical environment, such as low carrier density and random distribution, greatly limits their development as proton-conducting membranes. Herein, Nafion intercalated polydopamine-modified graphene oxide (ND-D) membranes are prepared, followed by thermal rearrangement-electrostatic induction to manipulate –SO3H group arrangement in interlayer channels. Experiments and molecular dynamics simulations demonstrate the specific process mechanism of carrier rearrangement: heat treatment promotes the movement of Nafion chains, and then induces their acid groups to enrich near the –NH2/–NH– groups on channel wall. Such carrier arrangement creates efficient and stable interfacial channels for proton conduction. This novel membrane, therefore, achieves the proton conductivity of 309 and 55.4 mS cm−1 under 100% and 40% RH, respectively, outclassing those of benchmark Nafion membrane. This further permits a 130% improvement in hydrogen fuel cell performance. Meanwhile, the carrier rearrangement imparts over two times’ enhancement in interlayer interaction and hence obviously enhanced membrane stability. Furthermore, a similar sulfonated poly(ether ether ketone) intercalated lamellar membrane is prepared to prove the universality of this strategy. The elaboration of carrier rearrangement in confined channels may pave a way for the rational design of high-efficiency membrane materials.