Supramolecular Anchoring of Polyoxometalate Amphiphiles into Nafion Nanophases for Enhanced Proton Conduction

Abstract

Advanced proton exchange membranes (PEMs) are highly desirable in emerging sustainable energy technology. However, the further improvement of commercial perfluorosulfonic acid PEMs represented by Nafion is hindered by the lack of precise modification strategy due to their chemical inertness and low compatibility. Here, we report the robust assembly of polyethylene glycol grafted polyoxometalate amphiphile (GSiW 11 ) into the ionic nanophases of Nafion, which largely enhances the comprehensive performance of Nafion. GSiW 11 can coassemble with Nafion through multiple supramolecular interactions and realize a stable immobilization. The incorporation of GSiW 11 can increase the whole proton content in the system and induce the hydrated ionic nanophase to form a wide channel for proton transport; meanwhile, GSiW 11 can reinforce the Nafion ionic nanophase by noncovalent cross-linking. Based on these synergistic effects, the hybrid PEMs show multiple enhancements in proton conductivity, tensile strength, and fuel cell power density, which are all superior to the pristine Nafion. This work demonstrates the intriguing advantage of molecular nanoclusters as supramolecular enhancers to develop high-performance electrolyte materials.

Highly Sensitive Artificial Skin Perception Enabled by a Bio-inspired Interface

“…This is because Nafion is a kind of cation-exchange membrane. Anions are fixed onto the polymer structure, while cations are movable throughout the membrane . If piezoionic sensors are bent under an external strain or stress, the cations in the polyelectrolyte move to the stretching side and form a gradient concentration of ions throughout the device.…”

“…Anions are fixed onto the polymer structure, while cations are movable throughout the membrane. 30 If piezoionic sensors are bent under an external strain or stress, the cations in the polyelectrolyte move to the stretching side and form a gradient concentration of ions throughout the device. The gradient concentration will lead to sensing voltage response, which can be detected by an electrochemical station within the open-circuit voltage mode.…”

Ionic-Nanophase Hybridization of Nafion by Supramolecular Patching for Enhanced Proton Selectivity in Redox Flow Batteries

“…For example, quantum dots (2–5 nm) are proposed to well meet these two requirements for the hybridization of high-performance proton exchange membranes . Besides, polyoxometalates (POMs), a class of molecular-defined ionic metal oxide nanoclusters (∼1 nm), which are usually employed as building blocks to fabricate functional hybrid materials, have recently attracted much attention. − Their super acidity, chemical affinity, and high proton conductivity (∼0.2 S cm –1 ) enable them to be readily loaded into the INP as multifunctional nanofillers. − However, the most commonly used POMs are anionic and difficult to be stably immobilized when hybridizing with Nafion for their high water solubility and unfavorable repulsion with anionic −SO 3 – . − For organic additives, the asymmetric molecular structure of block copolymers can enable them interfacial-active and impart a tunable affinity with targeted microphase-separated polymer matrices. With rational design, block copolymers can act as compatibilizers to assist the loading of other inorganic additives into the INP through supramolecular interactions. − …”

Supramolecular Assembly and Microscopic Dynamics Modulation of Nanoscale Inorganic Cryptand and Polymer Complex for Versatile Design of Flexible Single-Ion Conductors

“…New strategies are desired for PNC SSE to resolve the trade-offs among the high loading of macroscopic inorganic ion channels, the compatibility of polymer/inorganic phase, and the preservation of polymers’ mechanical performance. The combination of self-assembled ion channels and phase separation offers solutions by decoupling the formation of ionic conducting pathways from the strengthening of the materials’ mechanical properties. ,,− ,− Nanoscale metal oxide clusters have been complexed with polymers for SSEs; nevertheless, it is only applicable for proton transportation due to the narrow chemical compatibility of polymer phases to cations. , Herein, nanoscale inorganic cryptand molecules carrying different types of cations (Ag + , Na + K + , or Ca 2+ ) are complexed with cationic polymers via ionic interaction, respectively, and the hybrid materials further phase separate into lamellar or hexagonal columnar structures composed of polymer and inorganic phases. In the inorganic phase, the inorganic cryptand molecules assemble into ion channels for the feasible transportation of various cations.…”