Isotope Effect on Diffusion in Nafion Studied by NMR Diffusometry

Privalov, A. F.; Galitskaya, Elena; Синицын, В. В.; Vogel, Michael

doi:10.1007/s00723-019-01167-z

Cited by 7 publications

(5 citation statements)

References 40 publications

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“…The proton transfer is also facilitated by the change in the location of the short O–H…O bonds through the proton hops, followed by the formation of other short bonds due to the vibrations of the H-bond network. The Grotthuss mechanism explains the higher rate of proton transfer in ion-exchange membranes than that of other cations ( Figure 2 ) [ 100 , 116 , 117 , 118 , 119 ]. This is also the reason for the violation of the regularity of the change in water diffusion coefficients with a radius of monovalent ion ( Figure 1 ).…”

Section: Ion Transfer In H + -Forms Of Membranementioning

confidence: 99%

Ionic Mobility in Ion-Exchange Membranes

Стенина

Yaroslavtsev

2021

Membranes

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Membrane technologies are widely demanded in a number of modern industries. Ion-exchange membranes are one of the most widespread and demanded types of membranes. Their main task is the selective transfer of certain ions and prevention of transfer of other ions or molecules, and the most important characteristics are ionic conductivity and selectivity of transfer processes. Both parameters are determined by ionic and molecular mobility in membranes. To study this mobility, the main techniques used are nuclear magnetic resonance and impedance spectroscopy. In this comprehensive review, mechanisms of transfer processes in various ion-exchange membranes, including homogeneous, heterogeneous, and hybrid ones, are discussed. Correlations of structures of ion-exchange membranes and their hydration with ion transport mechanisms are also reviewed. The features of proton transfer, which plays a decisive role in the membrane used in fuel cells and electrolyzers, are highlighted. These devices largely determine development of hydrogen energy in the modern world. The features of ion transfer in heterogeneous and hybrid membranes with inorganic nanoparticles are also discussed.

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Section: Ion Transfer In H + -Forms Of Membranementioning

confidence: 99%

Ionic Mobility in Ion-Exchange Membranes

Стенина

Yaroslavtsev

2021

Membranes

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“…Low hydration levels favor vehicle transport, which facilitates charge transport by diffusion of oxonium ions. ,− Higher hydration degrees favor the Grotthus mechanism, − also referred to as the hopping or relay mechanism. Here, charge transport is mediated via protons that are transferred from water to water molecules. , This requires structural reorientation and displacement of water molecules to transfer protons from one water molecule to another.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast Proton Conduction in an Aqueous Electrolyte Confined in Adamantane-like Micropores of a Sulfonated, Aromatic Framework

Winterstein,

Privalov,

Greve

et al. 2023

J. Am. Chem. Soc.

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“…It is important to note that water remains mobile down to very low temperatures of ~200 K, and the observed change in the D NMR (T) dependence may be associated with the water vitrification processes [ 26 ]. This D NMR (T) behavior is typical for various perfluorinated sulfopolymers [ 30 , 31 , 32 ]. For comparison, the self-diffusion coefficient of the Nafion ® 212 membrane measured under identical environmental conditions [ 30 ] shows qualitatively similar D NMR (T) dependence.…”

Section: Resultsmentioning

confidence: 98%

“…This D NMR (T) behavior is typical for various perfluorinated sulfopolymers [ 30 , 31 , 32 ]. For comparison, the self-diffusion coefficient of the Nafion ® 212 membrane measured under identical environmental conditions [ 30 ] shows qualitatively similar D NMR (T) dependence. The crossover in D NMR (T) occurs at approximately the same temperature (T c = 253 for co-PNIS 70/30 and T c = 255 K for Nafion ® 212) and the activation energies coincide within the experimental error for both polymers at high (T > T c ) and low (T < T c ) temperatures.…”

Section: Resultsmentioning

confidence: 98%

Preparation and Study of Sulfonated Co-Polynaphthoyleneimide Proton-Exchange Membrane for a H2/Air Fuel Cell

et al. 2020

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The sulfonated polynaphthoyleneimide polymer (co-PNIS70/30) was prepared by copolymerization of 4,4′-diaminodiphenyl ether-2,2′-disulfonic acid (ODAS) and 4,4’-methylenebisanthranilic acid (MDAC) with ODAS/MDAC molar ratio 0.7/0.3. High molecular weight co-PNIS70/30 polymers were synthesized either in phenol or in DMSO by catalytic polyheterocyclization in the presence of benzoic acid and triethylamine. The titration reveals the ion-exchange capacity of the polymer equal to 2.13 meq/g. The membrane films were prepared by casting polymer solution. Conductivities of the polymer films were determined using both in- and through-plane geometries and reached ~96 and ~60 mS/cm, respectively. The anisotropy of the conductivity is ascribed to high hydration of the surface layer compared to the bulk. SFG NMR diffusometry shows that, in the temperature range from 213 to 353 K, the 1H self-diffusion coefficient of the co-PNIS70/30 membrane is about one third of the diffusion coefficient of Nafion® at the same humidity. However, temperature dependences of proton conductivities of Nafion® and of co-PNIS70/30 membranes are nearly identical. Membrane–electrode assemblies (MEAs) based on co-PNIS70/30 were fabricated by different procedures. The optimal MEAs with co-PNIS70/30 membranes are characterized by maximum output power of ~370 mW/cm2 at 80 °C. It allows considering sulfonated co-PNIS70/30 polynaphthoyleneimides membrane attractive for practical applications.

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Isotope Effect on Diffusion in Nafion Studied by NMR Diffusometry

Cited by 7 publications

References 40 publications

Ionic Mobility in Ion-Exchange Membranes

Ionic Mobility in Ion-Exchange Membranes

Ultrafast Proton Conduction in an Aqueous Electrolyte Confined in Adamantane-like Micropores of a Sulfonated, Aromatic Framework

Preparation and Study of Sulfonated Co-Polynaphthoyleneimide Proton-Exchange Membrane for a H2/Air Fuel Cell

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