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Winterstein S, Privalov AF, Greve C, Siegel R, Pötzschner B, Bettermann M, Adolph L, Timm J, Marschall R, Rössler EA, Herzig EM, Vogel M, Senker J. Ultrafast Proton Conduction in an Aqueous Electrolyte Confined in Adamantane-like Micropores of a Sulfonated, Aromatic Framework. J Am Chem Soc 2023; 145:27563-27575. [PMID: 38060438 PMCID: PMC10740000 DOI: 10.1021/jacs.3c09257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 11/12/2023] [Accepted: 11/20/2023] [Indexed: 12/21/2023]
Abstract
Sulfonated, cross-linked porous polymers are promising frameworks for aqueous high-performance electrolyte-host systems for electrochemical energy storage and conversion. The systems offer high proton conductivities, excellent chemical and mechanical stabilities, and straightforward water management. However, little is known about mass transport mechanisms in such nanostructured hosts. We report on the synthesis and postsynthetic sulfonation of an aromatic framework (SPAF-2) with a 3D-interconnected nanoporosity and varying sulfonation degrees. Water adsorption produces the system SPAF-2H20. It features proton exchange capacities up to 6 mequiv g-1 and exceptional proton conductivities of about 1 S cm-1. Two contributions are essential for the highly efficient transport. First, the nanometer-sized pores link the charge transport to the diffusion of adsorbed water molecules, which is almost as fast as bulk water. Second, continuous exchange between interface-bound and mobile species enhances the conductivities at elevated temperatures. SPAF-2H20 showcases how to tailor nanostructured electrolyte-host systems with liquid-like conductivities.
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Affiliation(s)
- Simon
F. Winterstein
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Alexei F. Privalov
- Institute
for Condensed Matter Physics, Technical
University of Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany
| | - Christopher Greve
- Dynamics
and Structure Formation, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Renée Siegel
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Björn Pötzschner
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Michael Bettermann
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Lea Adolph
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Jana Timm
- Physical
Chemistry III, Department of Chemistry, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Roland Marschall
- Physical
Chemistry III, Department of Chemistry, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Ernst A. Rössler
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Eva M. Herzig
- Dynamics
and Structure Formation, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
| | - Michael Vogel
- Institute
for Condensed Matter Physics, Technical
University of Darmstadt, Hochschulstr. 6, 64289 Darmstadt, Germany
| | - Jürgen Senker
- Inorganic
Chemistry III and Northern Bavarian NMR Centre, University of Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany
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Privalov AF, Sinitsyn VV, Vogel M. Transport Mechanism in Nafion Revealed by Detailed Comparison of 1H and 17O Nuclear Magnetic Resonance Diffusion Coefficients. J Phys Chem Lett 2023; 14:9335-9340. [PMID: 37819873 DOI: 10.1021/acs.jpclett.3c02229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
We use 1H and 17O NMR static field gradient diffusometry to measure self-diffusion coefficients of protons (DH) and oxygens (DO) in Nafion 212 with various hydration levels (λ = 4-18). For all samples and both nuclei, we obtain activation energies (Ea) of ≈0.19 eV. Analyzing the hydration-level dependence of DH and DO, we find DO/DH ≈ 1 at λ ≈ 18, resembling the situation in bulk water, while oxygen diffusion becomes faster than proton diffusion when the water content is decreased, leading to DO/DH ≈ 1.2 at λ ≈ 4. A comparison with literature data for acidic bulk solutions implies that faster oxygen than proton diffusion results from the existence of the polymer framework. To rationalize the observed ratios DO/DH ≥ 1, we consider a bimodal dynamical model in which the interactions of H+(H2O)m ions with neighboring SO3- groups lead to slower water dynamics in the vicinity of the polymer framework than in the center of the water nanochannels.
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Affiliation(s)
- Alexei F Privalov
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstrasse 6, 64289 Darmstadt, Germany
| | - Vitaly V Sinitsyn
- National Research University High School of Economics, Myasnitskaya 20, 101000 Moscow, Russia
| | - Michael Vogel
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstrasse 6, 64289 Darmstadt, Germany
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Becher M, Lichtinger A, Minikejew R, Vogel M, Rössler EA. NMR Relaxometry Accessing the Relaxation Spectrum in Molecular Glass Formers. Int J Mol Sci 2022; 23:ijms23095118. [PMID: 35563506 PMCID: PMC9105706 DOI: 10.3390/ijms23095118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 12/10/2022] Open
Abstract
It is a longstanding question whether universality or specificity characterize the molecular dynamics underlying the glass transition of liquids. In particular, there is an ongoing debate to what degree the shape of dynamical susceptibilities is common to various molecular glass formers. Traditionally, results from dielectric spectroscopy and light scattering have dominated the discussion. Here, we show that nuclear magnetic resonance (NMR), primarily field-cycling relaxometry, has evolved into a valuable method, which provides access to both translational and rotational motions, depending on the probe nucleus. A comparison of 1H NMR results indicates that translation is more retarded with respect to rotation for liquids with fully established hydrogen-bond networks; however, the effect is not related to the slow Debye process of, for example, monohydroxy alcohols. As for the reorientation dynamics, the NMR susceptibilities of the structural (α) relaxation usually resemble those of light scattering, while the dielectric spectra of especially polar liquids have a different broadening, likely due to contributions from cross correlations between different molecules. Moreover, NMR relaxometry confirms that the excess wing on the high-frequency flank of the α-process is a generic relaxation feature of liquids approaching the glass transition. However, the relevance of this feature generally differs between various methods, possibly because of their different sensitivities to small-amplitude motions. As a major advantage, NMR is isotope specific; hence, it enables selective studies on a particular molecular entity or a particular component of a liquid mixture. Exploiting these possibilities, we show that the characteristic Cole-Davidson shape of the α-relaxation is retained in various ionic liquids and salt solutions, but the width parameter may differ for the components. In contrast, the low-frequency flank of the α-relaxation can be notably broadened for liquids in nanoscopic confinements. This effect also occurs in liquid mixtures with a prominent dynamical disparity in their components.
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Affiliation(s)
- Manuel Becher
- Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany; (M.B.); (A.L.); (R.M.)
| | - Anne Lichtinger
- Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany; (M.B.); (A.L.); (R.M.)
| | - Rafael Minikejew
- Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany; (M.B.); (A.L.); (R.M.)
| | - Michael Vogel
- Institut für Physik Kondensierter Materie, Technische Universität Darmstadt, 64289 Darmstadt, Germany;
| | - Ernst A. Rössler
- Nordbayerisches NMR Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany; (M.B.); (A.L.); (R.M.)
- Correspondence:
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Chiou DS, Chuang YC, Chang CK, Hsu CH, Lin LC, Kang DY. X-ray diffraction for probing free energy profiles and self-diffusivity of gases in metal–organic frameworks. CrystEngComm 2022. [DOI: 10.1039/d2ce00968d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This paper presents a novel methodology for measuring the free energy profiles and the self-diffusivity of gases in crystalline microporous materials.
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Affiliation(s)
- Da-Shiuan Chiou
- Department of Chemical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
| | - Yu-Chun Chuang
- National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu, 30076 Taiwan
| | - Chung-Kai Chang
- National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu, 30076 Taiwan
| | - Cheng-Hsun Hsu
- Department of Chemical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
| | - Li-Chiang Lin
- Department of Chemical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
| | - Dun-Yen Kang
- Department of Chemical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
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Becher M, Wohlfromm T, Rössler EA, Vogel M. Molecular dynamics simulations vs field-cycling NMR relaxometry: Structural relaxation mechanisms in the glass-former glycerol revisited. J Chem Phys 2021; 154:124503. [PMID: 33810699 DOI: 10.1063/5.0048131] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We combine field-cycling (FC) relaxometry and molecular dynamics (MD) simulations to study the rotational and translational dynamics associated with the glassy slowdown of glycerol. The 1H NMR spin-lattice relaxation rates R1(ω) probed in the FC measurements for different isotope-labelled compounds are computed from the MD trajectories for broad frequency and temperature ranges. We find high correspondence between experiment and simulation. Concerning the rotational motion, we observe that the aliphatic and hydroxyl groups show similar correlation times but different stretching parameters, while the overall reorientation associated with the structural relaxation remains largely isotropic. Additional analysis of the simulation results reveals that transitions between different molecular configurations are slow on the time scale of the structural relaxation at least at sufficiently high temperatures, indicating that glycerol rotates at a rigid entity, but the reorientation is slower for elongated than for compact conformers. The translational contribution to R1(ω) is well described by the force-free hard sphere model. At sufficiently low frequencies, universal square-root laws provide access to the molecular diffusion coefficients. In both experiment and simulation, the time scales of the rotational and translational motions show an unusually large separation, which is at variance with the Stokes-Einstein-Debye relation. To further explore this effect, we investigate the structure and dynamics on various length scales in the simulations. We observe that a prepeak in the static structure factor S(q), which is related to a local segregation of aliphatic and hydroxyl groups, is accompanied by a peak in the correlation times τ(q) from coherent scattering functions.
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Affiliation(s)
- M Becher
- Nordbayerisches NMR-Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany
| | - T Wohlfromm
- Institute of Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstraße 6, 64289 Darmstadt, Germany
| | - E A Rössler
- Nordbayerisches NMR-Zentrum, Universität Bayreuth, 95440 Bayreuth, Germany
| | - M Vogel
- Institute of Condensed Matter Physics, Technische Universität Darmstadt, Hochschulstraße 6, 64289 Darmstadt, Germany
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