1
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Kaiser S, Yue Z, Peng Y, Nguyen TD, Chen S, Teng D, Voth GA. Molecular Dynamics Simulation of Complex Reactivity with the Rapid Approach for Proton Transport and Other Reactions (RAPTOR) Software Package. J Phys Chem B 2024; 128:4959-4974. [PMID: 38742764 PMCID: PMC11129700 DOI: 10.1021/acs.jpcb.4c01987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 05/05/2024] [Accepted: 05/06/2024] [Indexed: 05/16/2024]
Abstract
Simulating chemically reactive phenomena such as proton transport on nanosecond to microsecond and beyond time scales is a challenging task. Ab initio methods are unable to currently access these time scales routinely, and traditional molecular dynamics methods feature fixed bonding arrangements that cannot account for changes in the system's bonding topology. The Multiscale Reactive Molecular Dynamics (MS-RMD) method, as implemented in the Rapid Approach for Proton Transport and Other Reactions (RAPTOR) software package for the LAMMPS molecular dynamics code, offers a method to routinely sample longer time scale reactive simulation data with statistical precision. RAPTOR may also be interfaced with enhanced sampling methods to drive simulations toward the analysis of reactive rare events, and a number of collective variables (CVs) have been developed to facilitate this. Key advances to this methodology, including GPU acceleration efforts and novel CVs to model water wire formation are reviewed, along with recent applications of the method which demonstrate its versatility and robustness.
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Affiliation(s)
- Scott Kaiser
- Department
of Chemistry, Chicago Center for Theoretical Chemistry, James Franck
Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States
| | - Zhi Yue
- Department
of Chemistry, Chicago Center for Theoretical Chemistry, James Franck
Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States
| | - Yuxing Peng
- NVIDIA
Corporation, Santa
Clara, California 95051, United States
| | - Trung Dac Nguyen
- Research
Computing Center, The University of Chicago, Chicago, Illinois 60637, United States
| | - Sijia Chen
- Department
of Chemistry, Chicago Center for Theoretical Chemistry, James Franck
Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States
| | - Da Teng
- Department
of Chemistry, Chicago Center for Theoretical Chemistry, James Franck
Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States
| | - Gregory A. Voth
- Department
of Chemistry, Chicago Center for Theoretical Chemistry, James Franck
Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, United States
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2
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Zhang Z, Cui R, Jiang X, Yu C, Zhou Y. Effect of ionic groups on the morphology and transport properties in a novel perfluorinated ionomer containing sulfonic and phosphonic acid groups: a molecular dynamics study. Phys Chem Chem Phys 2024; 26:12806-12819. [PMID: 38619877 DOI: 10.1039/d4cp00962b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2024]
Abstract
Combining the phosphonic acid group with the sulfonic acid group in PEMs has been shown to be an effective strategy for improving the fuel cell performance. However, the interplay of two different ionic groups and the resulting effect on the membrane properties have not been fully elucidated. Here, we used classical molecular dynamics simulation to investigate the morphologies, transport properties and effects of ionic groups in a novel perfluorinated PEM containing two ionic groups (PFSA-PFPA) in comparison to the corresponding homopolymers. Phase separations between hydrophilic and hydrophobic domains are confirmed in these PEMs and result from the evolution of water clusters formed around the ionic groups. The combination of both ionic groups brings a complicated morphological feature in PFSA-PFPA, with near-cylindrical aqueous domains of large length scales interconnected by tortuous domains of small sizes. And we found that the self-diffusion coefficients of water molecules are strongly related to morphologies, with the water transport in PFSA-PFPA lying between two analogous homopolymers. At the molecular level, we found that the sulfonic and phosphonic acid groups have distinct effects on the coordination behaviors and the dynamics of water molecules and hydronium ions. Strong electrostatic interactions lead to compact coordination structures and sluggish dynamics of hydronium ions around phosphonic acid groups, which determine the morphological evolution and transport properties in PFSA-PFPA. Our study affords insights into the relationship between molecular characteristics and transport properties bridged by phase-separated morphologies in a novel PEM containing both sulfonic acid and phosphonic acid groups, which deepens the understanding of the interplay between two ionic groups and may inspire the rational design of high-performance PEMs.
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Affiliation(s)
- Zongwei Zhang
- School of Chemistry & Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Key Laboratory of Electrical Insulation and Thermal Aging, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China.
| | - Rui Cui
- School of Chemistry & Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Key Laboratory of Electrical Insulation and Thermal Aging, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China.
| | - Xuesong Jiang
- School of Chemistry & Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Key Laboratory of Electrical Insulation and Thermal Aging, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China.
- Key Laboratory of Green and High-end Utilization of Salt Lake Resources, Chinese Academy of Sciences, China
| | - Chunyang Yu
- School of Chemistry & Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Key Laboratory of Electrical Insulation and Thermal Aging, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China.
- Key Laboratory of Green and High-end Utilization of Salt Lake Resources, Chinese Academy of Sciences, China
| | - Yongfeng Zhou
- School of Chemistry & Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Key Laboratory of Electrical Insulation and Thermal Aging, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China.
- Key Laboratory of Green and High-end Utilization of Salt Lake Resources, Chinese Academy of Sciences, China
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3
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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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4
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Sunda AP, Singh S, Yadav S, Singh RK. Atomistic Simulations of Hydrated Sulfonated Polybenzophenone Block Copolymer Membranes. Chemphyschem 2023; 24:e202300104. [PMID: 37260415 DOI: 10.1002/cphc.202300104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 06/01/2023] [Accepted: 06/01/2023] [Indexed: 06/02/2023]
Abstract
We present a classical molecular dynamics simulations study on the nanostructures of the sulfonated polybenzophenone (SPK) block copolymer membranes at 300 K and 353 K. The results of the radial distribution function (RDF) show that the interactions of the sulfonate groups of the membrane with the hydronium ions are more significant than those of water due to the strong electrostatic attraction over the hydrogen bonding. However, the effect of temperatures on the RDF profile seems insignificant. Furthermore, the spatial distribution function (SDF) portrays that the sulfonate groups of the hydrophilic components are preferential binding sites for hydronium ions against the hydrophobic counterpart of the SPK membrane. The mobility of the H3 O+ ions at 300 K and 353 K is two (or three) times lower than that of Nafion/Aciplex. However, the diffusion coefficients for water molecules closely agree with Nafion/Aciplex. This study suggests that water clusters are more localized around the sulfonate groups in the SPK membranes. Thus, the molecular modeling study of SPK block copolymer membranes is warranted to design better-performing membrane electrolytes.
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Affiliation(s)
- Anurag Prakash Sunda
- Department of Chemistry, J. C. Bose University of Science and Technology, YMCA, Faridabad, 121006, India
| | - Soni Singh
- Department of Chemistry, Jagdam College, Jai Prakash University, Chapra, 841301, Bihar, India
| | - Sonia Yadav
- Department of Chemistry, J. C. Bose University of Science and Technology, YMCA, Faridabad, 121006, India
| | - Raman K Singh
- Department of Chemistry, Jagdam College, Jai Prakash University, Chapra, 841301, Bihar, India
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5
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Safronova EY, Lysova AA, Voropaeva DY, Yaroslavtsev AB. Approaches to the Modification of Perfluorosulfonic Acid Membranes. MEMBRANES 2023; 13:721. [PMID: 37623782 PMCID: PMC10456953 DOI: 10.3390/membranes13080721] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 08/01/2023] [Accepted: 08/05/2023] [Indexed: 08/26/2023]
Abstract
Polymer ion-exchange membranes are featured in a variety of modern technologies including separation, concentration and purification of gases and liquids, chemical and electrochemical synthesis, and hydrogen power generation. In addition to transport properties, the strength, elasticity, and chemical stability of such materials are important characteristics for practical applications. Perfluorosulfonic acid (PFSA) membranes are characterized by an optimal combination of these properties. Today, one of the most well-known practical applications of PFSA membranes is the development of fuel cells. Some disadvantages of PFSA membranes, such as low conductivity at low humidity and high temperature limit their application. The approaches to optimization of properties are modification of commercial PFSA membranes and polymers by incorporation of different additive or pretreatment. This review summarizes the approaches to their modification, which will allow the creation of materials with a different set of functional properties, differing in ion transport (first of all proton conductivity) and selectivity, based on commercially available samples. These approaches include the use of different treatment techniques as well as the creation of hybrid materials containing dopant nanoparticles. Modification of the intrapore space of the membrane was shown to be a way of targeting the key functional properties of the membranes.
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Affiliation(s)
- Ekaterina Yu. Safronova
- Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninsky Avenue, 31, 119991 Moscow, Russia; (A.A.L.); (D.Y.V.); (A.B.Y.)
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6
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Achar SK, Bernasconi L, DeMaio RI, Howard KR, Johnson JK. In Silico Demonstration of Fast Anhydrous Proton Conduction on Graphanol. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37192530 DOI: 10.1021/acsami.3c04022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Development of new materials capable of conducting protons in the absence of water is crucial for improving the performance, reducing the cost, and extending the operating conditions for proton exchange membrane fuel cells. We present detailed atomistic simulations showing that graphanol (hydroxylated graphane) will conduct protons anhydrously with very low diffusion barriers. We developed a deep learning potential (DP) for graphanol that has near-density functional theory accuracy but requires a very small fraction of the computational cost. We used our DP to calculate proton self-diffusion coefficients as a function of temperature, to estimate the overall barrier to proton diffusion, and to characterize the impact of thermal fluctuations as a function of system size. We propose and test a detailed mechanism for proton conduction on the surface of graphanol. We show that protons can rapidly hop along Grotthuss chains containing several hydroxyl groups aligned such that hydrogen bonds allow for conduction of protons forward and backward along the chain without hydroxyl group rotation. Long-range proton transport only takes place as new Grotthuss chains are formed by rotation of one or more hydroxyl groups in the chain. Thus, the overall diffusion barrier consists of a convolution of the intrinsic proton hopping barrier and the intrinsic hydroxyl rotation barrier. Our results provide a set of design rules for developing new anhydrous proton conducting membranes with even lower diffusion barriers.
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Affiliation(s)
- Siddarth K Achar
- Computational Modeling & Simulation Program, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Chemical & Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Leonardo Bernasconi
- Center for Research Computing and Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Ruby I DeMaio
- Department of Chemical & Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - Katlyn R Howard
- Department of Chemical & Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | - J Karl Johnson
- Department of Chemical & Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
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7
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Cui R, Li S, Yu C, Zhou Y. The Evolution of Hydrogen Bond Network in Nafion via Molecular Dynamics Simulation. Macromolecules 2023. [DOI: 10.1021/acs.macromol.2c02106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Affiliation(s)
- Rui Cui
- School of Chemistry & Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Key Laboratory of Electrical Insulation and Thermal Aging, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Shanlong Li
- School of Chemistry & Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Key Laboratory of Electrical Insulation and Thermal Aging, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Chunyang Yu
- School of Chemistry & Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Key Laboratory of Electrical Insulation and Thermal Aging, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Yongfeng Zhou
- School of Chemistry & Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Key Laboratory of Electrical Insulation and Thermal Aging, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
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8
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Hao H, Adams EM, Funke S, Schwaab G, Havenith M, Head-Gordon T. Highly Altered State of Proton Transport in Acid Pools in Charged Reverse Micelles. J Am Chem Soc 2023; 145:1826-1834. [PMID: 36633459 PMCID: PMC9881006 DOI: 10.1021/jacs.2c11331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Transport mechanisms of solvated protons of 1 M HCl acid pools, confined within reverse micelles (RMs) containing the negatively charged surfactant sodium bis(2-ethylhexyl) sulfosuccinate (NaAOT) or the positively charged cetyltrimethylammonium bromide (CTABr), are analyzed with reactive force field simulations to interpret dynamical signatures from TeraHertz absorption and dielectric relaxation spectroscopy. We find that the forward proton hopping events for NaAOT are further suppressed compared to a nonionic RM, while the Grotthuss mechanism ceases altogether for CTABr. We attribute the sluggish proton dynamics for both charged RMs as due to headgroup and counterion charges that expel hydronium and chloride ions from the interface and into the bulk interior, thereby increasing the pH of the acid pools relative to the nonionic RM. For charged NaAOT and CTABr RMs, the localization of hydronium near a counterion or conjugate base reduces the Eigen and Zundel configurations that enable forward hopping. Thus, localized oscillatory hopping dominates, an effect that is most extreme for CTABr in which the proton residence time increases dramatically such that even oscillatory hopping is slow.
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Affiliation(s)
- Hongxia Hao
- Kenneth
S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, California94720, United States
| | - Ellen M. Adams
- Cluster
of Excellence Physics of Life, Technische
Universität Dresden, 01307Dresden, Germany,Helmholtz-Zentrum
Dresden-Rossendorf, Institute of Resource
Ecology, 01328Dresden, Germany
| | - Sarah Funke
- Lehrstuhl
für Physkalische Chemie II, Ruhr
Universität Bochum, 44801Bochum, Germany
| | - Gerhard Schwaab
- Lehrstuhl
für Physkalische Chemie II, Ruhr
Universität Bochum, 44801Bochum, Germany
| | - Martina Havenith
- Lehrstuhl
für Physkalische Chemie II, Ruhr
Universität Bochum, 44801Bochum, Germany
| | - Teresa Head-Gordon
- Kenneth
S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, California94720, United States,Department
of Bioengineering, Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California94720, United States,Chemical
Sciences Division, Lawrence Berkeley National
Laboratory, Berkeley, California94720, United States,
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9
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Andrei IM, Barboiu M. Biomimetic Artificial Proton Channels. Biomolecules 2022; 12:biom12101473. [PMID: 36291682 PMCID: PMC9599858 DOI: 10.3390/biom12101473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 10/07/2022] [Accepted: 10/11/2022] [Indexed: 11/16/2022] Open
Abstract
One of the most common biochemical processes is the proton transfer through the cell membranes, having significant physiological functions in living organisms. The proton translocation mechanism has been extensively studied; however, mechanistic details of this transport are still needed. During the last decades, the field of artificial proton channels has been in continuous growth, and understanding the phenomena of how confined water and channel components mediate proton dynamics is very important. Thus, proton transfer continues to be an active area of experimental and theoretical investigations, and acquiring insights into the proton transfer mechanism is important as this enlightenment will provide direct applications in several fields. In this review, we present an overview of the development of various artificial proton channels, focusing mostly on their design, self-assembly behavior, proton transport activity performed on bilayer membranes, and comparison with protein proton channels. In the end, we discuss their potential applications as well as future development and perspectives.
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10
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Çelebi EB, Hacıvelioğlu F. Improving the mechanical and methanol crossover properties of fluorinated sulfonic acid functional polyphosphazenes by blending with polyvinylidene difluoride for fuel cell applications. POLYMER 2022. [DOI: 10.1016/j.polymer.2022.125175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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11
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Operating an ozone-evolving PEM electrolyser in tap water: A case study of water and ion transport. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.121063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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12
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Cui R, Li S, Yu C, Wang Y, Zhou Y. Understanding the mechanism of nitrogen transport in the perfluorinated sulfonic-acid hydrated membranes via molecular dynamics simulations. J Memb Sci 2022. [DOI: 10.1016/j.memsci.2022.120328] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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13
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Hu Y, Wang S, He Y, An L. Evaluation of proton transport and solvation effect in hydrated Nafion membrane with degradation. Phys Chem Chem Phys 2022; 24:29024-29033. [DOI: 10.1039/d2cp02817d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In proton exchange membrane fuel cells (PEMFCs), free radicals easily attack ionomers, resulting in membrane degradation.
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Affiliation(s)
- Yu Hu
- School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, 150001, China
| | - Shuai Wang
- School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, 150001, China
| | - Yurong He
- School of Energy Science and Engineering, Harbin Institute of Technology, Harbin, 150001, China
| | - Liang An
- Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China
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14
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Cheng RH, Cai H, Huang YR, Cui X, Chen Z, Chen HY, Ding S. A broad-range variable-temperature solid state NMR spectral and relaxation investigation of the water state in Nafion 117. Phys Chem Chem Phys 2021; 23:10899-10908. [PMID: 33908418 DOI: 10.1039/c9cp05978d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Understanding the water state in Nafion is not only crucial for operating a proton-exchange membrane (PEM)-based fuel cell, but also intimately related to the elucidation of the proton transport mechanism in a PEM. Although many studies have been published on this subject, some controversies and ambiguities remain unresolved. In this work, we design three different types of Nafion samples by substituting protons with lithium or sodium cations. We also pay special attention to the preparation of samples for carrying out broad-range variable temperature solid state NMR experiments so that no membrane dehydration occurs during the long experimental time at low temperatures. With these precautions and improvements, clear and largely straightforward information could be obtained to ensure minimal ambiguity and complexity in the interpretation of the experimental data. Our results show that about 40-60% of water remains unfrozen at -70 °C, depending on the type of the substituting cation. Both the 1H and 2H spectral and relaxation results indicate that water freezing starts from the center of the nanopores inside Nafion and increases gradually as the temperature decreases. The protons remain dissociated with sulfonate groups even at the lowest temperature we reached (-70 °C), whereas both lithium and sodium are associated with sulfonate groups at most temperatures below 0 °C. The experimental data also suggest that besides frozen and unfrozen water, there is broad distribution of water state and dynamics in Nafion as the temperature is lowered from above zero down to -70 °C. The effect of the size of the substituting cation significantly affects the properties of supercooled water by modifying the cation-water interaction and impeding the rotation of sulfonate groups. These novel results not only help us in establishing a better understanding of the water state in Nafion and its performance as a proton exchange mebrane, but also provide insights into water freezing, antifreeze and supercooling in other nanoscopic environments.
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Affiliation(s)
- Ren-Hao Cheng
- Department of Chemistry and Center for Nanoscience and Nanotechnology, National Sun Yat-sen University, 70 Lien-Hai Road, Kaohsiung, 80424, Taiwan.
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15
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Ureña N, Pérez-Prior MT, Levenfeld B, García-Salaberri PA. On the Conductivity of Proton-Exchange Membranes Based on Multiblock Copolymers of Sulfonated Polysulfone and Polyphenylsulfone: An Experimental and Modeling Study. Polymers (Basel) 2021; 13:363. [PMID: 33498770 PMCID: PMC7865426 DOI: 10.3390/polym13030363] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Revised: 01/17/2021] [Accepted: 01/19/2021] [Indexed: 12/26/2022] Open
Abstract
The effect of relative humidity (RH) and degree of sulfonation (DS) on the ionic conductivity and water uptake of proton-exchange membranes based on sulfonated multiblock copolymers composed of polysulfone (PSU) and polyphenylsulfone (PPSU) is examined experimentally and numerically. Three membranes with a different DS and ion-exchange capacity are analyzed. The heterogeneous structure of the membranes shows a random distribution of sulfonated (hydrophilic) and non-sulfonated (hydrophobic) domains, whose proton conductivity is modeled based on percolation theory. The mesoscopic model solves simplified Nernst-Planck and charge conservation equations on a random cubic network. Good agreement is found between the measured ionic conductivity and water uptake and the model predictions. The ionic conductivity increases with RH due to both the growth of the hydrated volume available for conduction and the decrease of the tortuosity of ionic transport pathways. Moreover, the results show that the ionic conductivity increases nonlinearly with DS, experiencing a strong rise when the DS is varied from 0.45 to 0.70, even though the water uptake of the membranes remains nearly the same. In contrast, the increase of the ionic conductivity between DS=0.70 and DS=0.79 is significantly lower, but the water uptake increases sharply. This is explained by the lack of microphase separation of both copolymer blocks when the DS is exceedingly high. Encouragingly, the copolymer membranes demonstrate a similar performance to Nafion under well hydrated conditions, which can be further optimized by a combination of numerical modeling and experimental characterization to develop new-generation membranes with better properties.
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Affiliation(s)
- Nieves Ureña
- Departamento de Ciencia e Ingeniería de Materiales e Ingeniería Química, IAAB, Universidad Carlos III de Madrid, 28911 Leganés, Spain; (N.U.); (M.T.P.-P.); (B.L.)
| | - M. Teresa Pérez-Prior
- Departamento de Ciencia e Ingeniería de Materiales e Ingeniería Química, IAAB, Universidad Carlos III de Madrid, 28911 Leganés, Spain; (N.U.); (M.T.P.-P.); (B.L.)
| | - Belén Levenfeld
- Departamento de Ciencia e Ingeniería de Materiales e Ingeniería Química, IAAB, Universidad Carlos III de Madrid, 28911 Leganés, Spain; (N.U.); (M.T.P.-P.); (B.L.)
| | - Pablo A. García-Salaberri
- Departamento de Ingeniería Térmica y de Fluidos, Universidad Carlos III de Madrid, 28911 Leganés, Spain
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16
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Insight from perfectly selective and ultrafast proton transport through anhydrous asymmetrical graphene oxide membranes under Grotthuss mechanism. J Memb Sci 2021. [DOI: 10.1016/j.memsci.2020.118735] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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17
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Stoppelman JP, McDaniel JG. Proton Transport in [BMIM+][BF4–]/Water Mixtures Near the Percolation Threshold. J Phys Chem B 2020; 124:5957-5970. [DOI: 10.1021/acs.jpcb.0c02487] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- John P. Stoppelman
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia30332-0400, United States
| | - Jesse G. McDaniel
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia30332-0400, United States
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18
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Zhu Z, Luo X, Sokolov AP, Paddison SJ. Proton Transfer in Phosphoric Acid-Based Protic Ionic Liquids: Effects of the Base. J Phys Chem A 2020; 124:4141-4149. [PMID: 32314922 DOI: 10.1021/acs.jpca.0c02863] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Electronic structure calculations were performed to understand highly decoupled conductivities recently reported in protic ionic liquids (PILs). To develop a molecular-level understanding of the mechanisms of proton conductivity in PILs, minimum-energy structures of trimethylamine, imidazole, lidocaine, and creatinine (CRT) with the addition of one to three phosphoric acid (PA) molecules were determined at the B3LYP/6-311G** level of theory with the inclusion of an implicit solvation model (SMD with ε = 61). The proton affinity of the bases and zero-point energy corrected binding energies were computed at a similar level of theory. Proton dissociation from PA occurs in all systems, resulting in the formation of ion pairs due to the relatively strong basicity of the bases (proton acceptors) and the effect of the high dielectric constant solvent in stabilizing the charge separation. The second and third PA molecules preferentially form "ring-like" hydrogen bonds with one another instead of forming hydrogen bonds at the donor and acceptor sites of the bases. Potential energy scans reveal that the bases with stronger proton affinity exert greater influence on the energetics of proton transfer between the individual PA molecules. However, the effects are minimal when shifted into a single-well from a double-well potential. Barrierless proton transfer was observed to occur in the CRT system with several PA molecules present, implying that the CRT may be a promising PA-based PIL.
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Affiliation(s)
- Zhenghao Zhu
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Xubo Luo
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
| | - Alexei P Sokolov
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, United States.,Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Stephen J Paddison
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
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19
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Flame-retardant AEMs based on organic-inorganic composite polybenzimidazole membranes with enhanced hydroxide conductivity. J Memb Sci 2019. [DOI: 10.1016/j.memsci.2019.117306] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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20
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Losch P, Joshi H, Stegmann N, Vozniuk O, Schmidt W. Studying Proton Mobility in Zeolites by Varying Temperature Infrared Spectroscopy. Molecules 2019; 24:molecules24173199. [PMID: 31484400 PMCID: PMC6749307 DOI: 10.3390/molecules24173199] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 08/26/2019] [Accepted: 08/29/2019] [Indexed: 11/16/2022] Open
Abstract
We report a varying temperature infrared spectroscopic (VTIR) study with partial deuterium isotopic exchange as a method for characterizing proton mobility in acidic materials. This VTIR technique permits the estimation of activation energies for proton diffusion. Different acidic materials comprising classical proton-conducting materials, such as transition metal phosphates and sulfonated solids, as well as different zeolites, are tested with this new method. The applicability of the method is thus extended to a vast library of materials. Its underlying principles and assumptions are clearly presented herein. Depending on the temperature ranges, different activation energies for proton transfer are observed irrespective of the different materials. In addition to the well-studied transition metal phosphates, Si-rich zeolites appear to be promising proton-transfer materials (with Eact < 40 kJ mol−1) for application in high-temperature (>150 °C) PEM fuel cells. They significantly outperform Nafion and sulfonated silica, which exhibit higher activation energies with Eact ~ 50 and 120 kJ mol−1, respectively.
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Affiliation(s)
- Pit Losch
- Max-Planck-Institut für Kohlenforschung, Department of Heterogeneous Catalysis, 45470 Mülheim an der Ruhr, Germany.
| | - Hrishikesh Joshi
- Max-Planck-Institut für Kohlenforschung, Department of Heterogeneous Catalysis, 45470 Mülheim an der Ruhr, Germany.
| | - Niklas Stegmann
- Max-Planck-Institut für Kohlenforschung, Department of Heterogeneous Catalysis, 45470 Mülheim an der Ruhr, Germany.
| | - Olena Vozniuk
- Max-Planck-Institut für Kohlenforschung, Department of Heterogeneous Catalysis, 45470 Mülheim an der Ruhr, Germany.
| | - Wolfgang Schmidt
- Max-Planck-Institut für Kohlenforschung, Department of Heterogeneous Catalysis, 45470 Mülheim an der Ruhr, Germany.
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21
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Ling X, Bonn M, Domke KF, Parekh SH. Correlated interfacial water transport and proton conductivity in perfluorosulfonic acid membranes. Proc Natl Acad Sci U S A 2019; 116:8715-8720. [PMID: 30988207 PMCID: PMC6500179 DOI: 10.1073/pnas.1817470116] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Water must be effectively transported and is also essential for maximizing proton conductivity within fuel-cell proton-exchange membranes (PEMs). Therefore, identifying relationships between PEM properties, water transport, and proton conductivity is essential for designing optimal PEMs. Here, we use coherent Raman spectroscopy to quantify real-time, in situ diffusivities of water subspecies, bulk-like and nonbulk-like (interfacial) water, in five different perfluorosulfonic acid (PFSA) PEMs. Although the PEMs were chemically diverse, water transport within them followed the same rule: Total water diffusivity could be represented by a linear combination of the bulk-like and interfacial water diffusivities. Moreover, the diffusivity of interfacial water was consistently larger than that of bulk-like water. These measurements of microscopic transport were combined with through-plane proton conductivity measurements to reveal the correlation between interfacial water transport and proton conductivity. Our results demonstrate the importance of maximizing the diffusivity and fractional contribution of interfacial water to maximize the proton conductivity in PFSA PEMs.
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Affiliation(s)
- Xiao Ling
- Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, D-55128 Mainz, Germany
| | - Mischa Bonn
- Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, D-55128 Mainz, Germany
| | - Katrin F Domke
- Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, D-55128 Mainz, Germany
| | - Sapun H Parekh
- Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, D-55128 Mainz, Germany;
- Department of Biomedical Engineering, University of Texas at Austin, Austin, TX 78712
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22
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Sorte EG, Paren BA, Rodriguez CG, Fujimoto C, Poirier C, Abbott LJ, Lynd NA, Winey KI, Frischknecht AL, Alam TM. Impact of Hydration and Sulfonation on the Morphology and Ionic Conductivity of Sulfonated Poly(phenylene) Proton Exchange Membranes. Macromolecules 2019. [DOI: 10.1021/acs.macromol.8b02013] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
| | - Benjamin A. Paren
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Christina G. Rodriguez
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
| | | | | | | | - Nathaniel A. Lynd
- McKetta Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712, United States
| | - Karen I. Winey
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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23
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Losch P, Joshi HR, Vozniuk O, Grünert A, Ochoa-Hernández C, Jabraoui H, Badawi M, Schmidt W. Proton Mobility, Intrinsic Acid Strength, and Acid Site Location in Zeolites Revealed by Varying Temperature Infrared Spectroscopy and Density Functional Theory Studies. J Am Chem Soc 2018; 140:17790-17799. [DOI: 10.1021/jacs.8b11588] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Pit Losch
- Department of Heterogeneous Catalysis, Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr 45470, Germany
| | - Hrishikesh R. Joshi
- Department of Heterogeneous Catalysis, Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr 45470, Germany
| | - Olena Vozniuk
- Department of Heterogeneous Catalysis, Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr 45470, Germany
| | - Anna Grünert
- Department of Heterogeneous Catalysis, Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr 45470, Germany
| | - Cristina Ochoa-Hernández
- Department of Heterogeneous Catalysis, Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr 45470, Germany
| | - Hicham Jabraoui
- Laboratoire Physique et Chimie Théoriques, UMR 7019 CNRS-Université de Lorraine, Saint Avold 57500, France
| | - Michael Badawi
- Laboratoire Physique et Chimie Théoriques, UMR 7019 CNRS-Université de Lorraine, Saint Avold 57500, France
| | - Wolfgang Schmidt
- Department of Heterogeneous Catalysis, Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr 45470, Germany
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24
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Bunkin NF, Shkirin AV, Kozlov VA, Ninham BW, Uspenskaya EV, Gudkov SV. Near-surface structure of Nafion in deuterated water. J Chem Phys 2018; 149:164901. [PMID: 30384746 DOI: 10.1063/1.5042065] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The swelling of a polymer ion-exchange membrane Nafion in water with various heavy isotope contents (D2O) was studied by photoluminescent UV spectroscopy. The photoluminescence arises because of the presence of sulfonic groups attached to the ends of the perfluorovinyl ether groups that form the tetrafluoroethylene (Teflon) backbone of Nafion. The width of the colloidal region, which is formed near the membrane surface as a result of the outgrowth of Nafion microfibers toward the bulk liquid, varies non-monotonically with D2O content, displaying a narrow maximum in the low concentration region. A significant insight into the unexpected isotopic effects revealed in swelling Nafion in deuterated water is provided. Mainly, the polymer swelling is very sensitive to small changes (on the order of several tens of parts per million) in the content of deuterium, which, for instance, can help in understanding the isotopic effects in living tissues.
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Affiliation(s)
- N F Bunkin
- Bauman Moscow State Technical University, Second Baumanskaya Str. 5, Moscow 105005, Russia
| | - A V Shkirin
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilova Str. 38, Moscow 119991, Russia
| | - V A Kozlov
- Bauman Moscow State Technical University, Second Baumanskaya Str. 5, Moscow 105005, Russia
| | - B W Ninham
- The Australian National University, Acton, ACT 2601, Australia
| | - E V Uspenskaya
- RUDN University, Miklukho-Maklaya Str. 6, Moscow 117198, Russia
| | - S V Gudkov
- Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilova Str. 38, Moscow 119991, Russia
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25
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Trigg EB, Gaines TW, Maréchal M, Moed DE, Rannou P, Wagener KB, Stevens MJ, Winey KI. Self-assembled highly ordered acid layers in precisely sulfonated polyethylene produce efficient proton transport. NATURE MATERIALS 2018; 17:725-731. [PMID: 29807986 DOI: 10.1038/s41563-018-0097-2] [Citation(s) in RCA: 115] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 04/30/2018] [Indexed: 05/21/2023]
Abstract
Recent advances in polymer synthesis have allowed remarkable control over chain microstructure and conformation. Capitalizing on such developments, here we create well-controlled chain folding in sulfonated polyethylene, leading to highly uniform hydrated acid layers of subnanometre thickness with high proton conductivity. The linear polyethylene contains sulfonic acid groups pendant to precisely every twenty-first carbon atom that induce tight chain folds to form the hydrated layers, while the methylene segments crystallize. The proton conductivity is on par with Nafion 117, the benchmark for fuel cell membranes. We demonstrate that well-controlled hairpin chain folding can be utilized for proton conductivity within a crystalline polymer structure, and we project that this structure could be adapted for ion transport. This layered polyethylene-based structure is an innovative and versatile design paradigm for functional polymer membranes, opening doors to efficient and selective transport of other ions and small molecules on appropriate selection of functional groups.
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Affiliation(s)
- Edward B Trigg
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Taylor W Gaines
- The George and Josephine Butler Polymer Research Laboratory, Department of Chemistry, University of Florida, Gainesville, FL, USA
| | - Manuel Maréchal
- Univ. Grenoble Alpes, CNRS, CEA, INAC-SyMMES, Grenoble, France
| | - Demi E Moed
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, USA
| | - Patrice Rannou
- Univ. Grenoble Alpes, CNRS, CEA, INAC-SyMMES, Grenoble, France
| | - Kenneth B Wagener
- The George and Josephine Butler Polymer Research Laboratory, Department of Chemistry, University of Florida, Gainesville, FL, USA
| | - Mark J Stevens
- Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, NM, USA
| | - Karen I Winey
- Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA, USA.
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26
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Vishnyakov A, Mao R, Lee MT, Neimark AV. Coarse-grained model of nanoscale segregation, water diffusion, and proton transport in Nafion membranes. J Chem Phys 2018; 148:024108. [PMID: 29331134 DOI: 10.1063/1.4997401] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a coarse-grained model of the acid form of Nafion membrane that explicitly includes proton transport. This model is based on a soft-core bead representation of the polymer implemented into the dissipative particle dynamics (DPD) simulation framework. The proton is introduced as a separate charged bead that forms dissociable Morse bonds with water beads. Morse bond formation and breakup artificially mimics the Grotthuss hopping mechanism of proton transport. The proposed DPD model is parameterized to account for the specifics of the conformations and flexibility of the Nafion backbone and sidechains; it treats electrostatic interactions in the smeared charge approximation. The simulation results qualitatively, and in many respects quantitatively, predict the specifics of nanoscale segregation in the hydrated Nafion membrane into hydrophobic and hydrophilic subphases, water diffusion, and proton mobility. As the hydration level increases, the hydrophilic subphase exhibits a percolation transition from a collection of isolated water clusters to a 3D network of pores filled with water embedded in the hydrophobic matrix. The segregated morphology is characterized in terms of the pore size distribution with the average size growing with hydration from ∼1 to ∼4 nm. Comparison of the predicted water diffusivity with the experimental data taken from different sources shows good agreement at high and moderate hydration and substantial deviation at low hydration, around and below the percolation threshold. This discrepancy is attributed to the dynamic percolation effects of formation and rupture of merging bridges between the water clusters, which become progressively important at low hydration, when the coarse-grained model is unable to mimic the fine structure of water network that includes singe molecule bridges. Selected simulations of water diffusion are performed for the alkali metal substituted membrane which demonstrate the effects of the counter-ions on membrane self-assembly and transport. The hydration dependence of the proton diffusivity reproduces semi-qualitatively the trend of the diverse experimental data, showing a sharp decrease around the percolation threshold. Overall, the proposed model opens up an opportunity to study self-assembly and water and proton transport in polyelectrolytes using computationally efficient DPD simulations, and, with further refinement, it may become a practical tool for theory informed design and optimization of perm-selective and ion-conducting membranes with improved properties.
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Affiliation(s)
- Aleksey Vishnyakov
- Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854-8058, USA
| | - Runfang Mao
- Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854-8058, USA
| | - Ming-Tsung Lee
- Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854-8058, USA
| | - Alexander V Neimark
- Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854-8058, USA
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27
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Kawakami T, Shigemoto I, Matubayasi N. Structure and permeability of ionomers studied by atomistic molecular simulation combined with the theory of solutions in the energy representation. J Chem Phys 2018; 148:214903. [PMID: 29884036 DOI: 10.1063/1.5018884] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Ionomers play a key role in forming the catalyst layer of polymer electrolyte fuel cells. In the present work, we performed atomistic molecular dynamics simulations and free-energy calculations with the energy-representation method for sulfonated polyethersulfone (SPES) and its derivatives toward the rational design of ionomers for carbon alloy catalysts. It was observed that H2O aggregates strongly in the branched SPES systems with fluorocarbons and is located homogeneously in the systems without fluorocarbons. The O2 permeability was then examined within the framework of the solubility-diffusion mechanism. The permeability was seen to be large for the branched SPES with fluorocarbons, indicating that the performance of ionomers as a permeation medium for O2 may be tuned by the flexibility and branching of the polymer chain.
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Affiliation(s)
- Tomonori Kawakami
- Advanced Materials Research Laboratories, Toray Industries, Inc., 2-1 Sonoyama 3-chome, Otsu, Shiga 520-0842, Japan
| | - Isamu Shigemoto
- Advanced Materials Research Laboratories, Toray Industries, Inc., 2-1 Sonoyama 3-chome, Otsu, Shiga 520-0842, Japan
| | - Nobuyuki Matubayasi
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
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28
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Exploring the effect of pendent side chain length on the structural and mechanical properties of hydrated perfluorosulfonic acid polymer membranes by molecular dynamics simulation. POLYMER 2018. [DOI: 10.1016/j.polymer.2018.05.033] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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29
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Mabuchi T, Tokumasu T. Relationship between Proton Transport and Morphology of Perfluorosulfonic Acid Membranes: A Reactive Molecular Dynamics Approach. J Phys Chem B 2018; 122:5922-5932. [DOI: 10.1021/acs.jpcb.8b02318] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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30
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Carpenter WB, Fournier JA, Lewis NHC, Tokmakoff A. Picosecond Proton Transfer Kinetics in Water Revealed with Ultrafast IR Spectroscopy. J Phys Chem B 2018; 122:2792-2802. [PMID: 29452488 DOI: 10.1021/acs.jpcb.8b00118] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Aqueous proton transport involves the ultrafast interconversion of hydrated proton species that are closely linked to the hydrogen bond dynamics of water, which has been a long-standing challenge to experiments. In this study, we use ultrafast IR spectroscopy to investigate the distinct vibrational transition centered at 1750 cm-1 in strong acid solutions, which arises from bending vibrations of the hydrated proton complex. Broadband ultrafast two-dimensional IR spectroscopy and transient absorption are used to measure vibrational relaxation, spectral diffusion, and orientational relaxation dynamics. The hydrated proton bend displays fast vibrational relaxation and spectral diffusion timescales of 200-300 fs; however, the transient absorption anisotropy decays on a remarkably long 2.5 ps timescale, which matches the timescale for hydrogen bond reorganization in liquid water. These observations are indications that the bending vibration of the aqueous proton complex is relatively localized, with an orientation that is insensitive to fast hydrogen bonding fluctuations and dependent on collective structural relaxation of the liquid to reorient. We conclude that the orientational relaxation is a result of proton transfer between configurations that are well described by a Zundel-like proton shared between two flanking water molecules.
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Affiliation(s)
- William B Carpenter
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics , The University of Chicago , Chicago , Illinois 60637 , United States
| | - Joseph A Fournier
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics , The University of Chicago , Chicago , Illinois 60637 , United States
| | - Nicholas H C Lewis
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics , The University of Chicago , Chicago , Illinois 60637 , United States
| | - Andrei Tokmakoff
- Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics , The University of Chicago , Chicago , Illinois 60637 , United States
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31
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Kim YJ, Kwon OH. Proton diffusion dynamics along a diol as a proton-conducting wire in a photo-amphiprotic model system. Phys Chem Chem Phys 2018; 18:32826-32839. [PMID: 27883126 DOI: 10.1039/c6cp06265b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We investigated the dynamics of excited-state proton transfer (ESPT) of photo-amphiprotic 7-hydroxyquinoline (7HQ) in the presence of a hydrogen (H)-bond bridging diol in a polar aprotic medium. The formation of 1 : 1 H-bonded complexes of 7HQ with various diols of different alkane chain lengths was revealed using steady-state electronic spectroscopy. With femtosecond-resolved fluorescence spectroscopy, cyclic H-bonded 1 : 1 complexes were found to undergo facile ESPT from the acidic enol to the basic imine group of 7HQ via the H-bond bridge. Through quantum chemical calculations, we found that the proton-transfer rate of the well-configured H-bonded complex correlated with the intramolecular H-bond length of a H-bond wiring diol molecule. Noncyclic, singly H-bonded 7HQ with a diol molecule was observed to undergo ESPT once another diol molecule diffuses to the noncyclic complex and accomplishes the formation of a reactive cyclic H-bonded 7HQ-(diol)2 complex, which was evidenced by the observation that the overall proton-transfer rate constant decreases when a longer-chain diol was used as the bridging wire part. The kinetic isotope effect on the proton relay was investigated to confirm that the nature of the activation barrier for the proton diffusion along the wire is isotope-sensitive proton tunnelling, while for the non-cyclic configuration, the isotope-insensitive H-bond bridge formation is a prerequisite for ESPT.
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Affiliation(s)
- Ye-Jin Kim
- Center for Soft and Living Matter, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea. and Department of Chemistry, School of Natural Science, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Oh-Hoon Kwon
- Center for Soft and Living Matter, Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea. and Department of Chemistry, School of Natural Science, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
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32
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Modarresi M, Franco-Gonzalez JF, Zozoulenko I. Morphology and ion diffusion in PEDOT:Tos. A coarse grained molecular dynamics simulation. Phys Chem Chem Phys 2018; 20:17188-17198. [DOI: 10.1039/c8cp02902d] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A Martini coarse-grained Molecular Dynamics (MD) model for the doped conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is developed. It is shown that the diffusion coefficients decrease exponentially as the hydration level is reduced.
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Affiliation(s)
- Mohsen Modarresi
- Laboratory of Organic Electronics
- Department of Science and Technology
- Linköping University
- 60174 Norrköping
- Sweden
| | - Juan Felipe Franco-Gonzalez
- Laboratory of Organic Electronics
- Department of Science and Technology
- Linköping University
- 60174 Norrköping
- Sweden
| | - Igor Zozoulenko
- Laboratory of Organic Electronics
- Department of Science and Technology
- Linköping University
- 60174 Norrköping
- Sweden
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33
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Okuwaki K, Mochizuki Y, Doi H, Kawada S, Ozawa T, Yasuoka K. Theoretical analyses on water cluster structures in polymer electrolyte membrane by using dissipative particle dynamics simulations with fragment molecular orbital based effective parameters. RSC Adv 2018; 8:34582-34595. [PMID: 35548624 PMCID: PMC9086946 DOI: 10.1039/c8ra07428c] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 10/01/2018] [Indexed: 12/04/2022] Open
Abstract
The mesoscopic structures of polymer electrolyte membrane (PEM) affect the performances of fuel cells. Nafion® with the Teflon® backbone has been the most widely used of all PEMs, but sulfonated poly-ether ether-ketone (SPEEK) having an aromatic backbone has drawn interest as an alternative to Nafion. In the present study, a series of dissipative particle dynamics (DPD) simulations were performed to compare Nafion and SPEEK. These PEM polymers were modeled by connected particles corresponding to the hydrophobic backbone and the hydrophilic moiety of sulfonic acid group. The water particle interacting with Nafion particles was prepared as well. The crucial interaction parameters among DPD particles were evaluated by a series of calculations based on the fragment molecular orbital (FMO) method in a non-empirical way (Okuwaki et al., J. Phys. Chem. B, 2018, 122, 338–347). Through the DPD simulations, the water and hydrophilic particles aggregated, forming cluster networks surrounded by the hydrophobic phase. The structural features of formed water clusters were investigated in detail. Furthermore, the differences in percolation behaviors between Nafion and SPEEK revealed much better connectivity among water clusters by Nafion. The present FMO-DPD simulation results were in good agreement with available experimental data. The mesoscopic structures of polymer electrolyte membrane (PEM) affect the performances of fuel cells.![]()
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Affiliation(s)
- Koji Okuwaki
- Department of Chemistry and Research Center for Smart Molecules
- Faculty of Science
- Rikkyo University
- Toshima-ku
- Japan
| | - Yuji Mochizuki
- Department of Chemistry and Research Center for Smart Molecules
- Faculty of Science
- Rikkyo University
- Toshima-ku
- Japan
| | - Hideo Doi
- Department of Chemistry and Research Center for Smart Molecules
- Faculty of Science
- Rikkyo University
- Toshima-ku
- Japan
| | - Shutaro Kawada
- Department of Chemistry and Research Center for Smart Molecules
- Faculty of Science
- Rikkyo University
- Toshima-ku
- Japan
| | | | - Kenji Yasuoka
- Department of Mechanical Engineering
- Keio University
- Yokohama 223-8522
- Japan
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34
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Jackson GL, Perroni DV, Mahanthappa MK. Roles of Chemical Functionality and Pore Curvature in the Design of Nanoporous Proton Conductors. J Phys Chem B 2017; 121:9429-9436. [PMID: 28971680 DOI: 10.1021/acs.jpcb.7b06366] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Grayson L. Jackson
- Department
of Chemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Dominic V. Perroni
- Department
of Chemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Mahesh K. Mahanthappa
- Department
of Chemistry, University of Wisconsin−Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States
- Department of Chemical Engineering & Materials Science, University of Minnesota, 421 Washington Avenue, S.E., Minneapolis, Minnesota 55455, United States
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35
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Affiliation(s)
- Jesse G. McDaniel
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
| | - Arun Yethiraj
- Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, United States
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36
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Bagusetty A, Choudhury P, Saidi WA, Derksen B, Gatto E, Johnson JK. Facile Anhydrous Proton Transport on Hydroxyl Functionalized Graphane. PHYSICAL REVIEW LETTERS 2017; 118:186101. [PMID: 28524689 DOI: 10.1103/physrevlett.118.186101] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Indexed: 06/07/2023]
Abstract
Graphane functionalized with hydroxyl groups is shown to rapidly conduct protons under anhydrous conditions through a contiguous network of hydrogen bonds. Density functional theory calculations predict remarkably low barriers to diffusion of protons along a 1D chain of surface hydroxyls. Diffusion is controlled by the local rotation of hydroxyl groups, a mechanism that is very different from that found in 1D water wires in confined nanopores or in bulk water. The proton mean square displacement in the 1D chain was observed to follow Fickian diffusion rather than the expected single-file mobility. A charge analysis reveals that the charge on the proton is essentially equally shared by all hydrogens bound to oxygens, effectively delocalizing the proton.
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Affiliation(s)
- Abhishek Bagusetty
- Computational Modeling and Simulation Program, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
| | - Pabitra Choudhury
- Department of Chemical Engineering, New Mexico Tech, Socorro, New Mexico 87801, USA
| | - Wisssam A Saidi
- Department of Mechanical and Materials Science, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
| | - Bridget Derksen
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
| | - Elizabeth Gatto
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
| | - J Karl Johnson
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
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37
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Fischer SA, Dunlap BI, Gunlycke D. Proton transport through hydrated chitosan-based polymer membranes under electric fields. ACTA ACUST UNITED AC 2017. [DOI: 10.1002/polb.24361] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
| | - Brett I. Dunlap
- Chemistry Division; Naval Research Laboratory; Washington DC 20375
| | - Daniel Gunlycke
- Chemistry Division; Naval Research Laboratory; Washington DC 20375
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38
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de Nicola A, Correa A, Milano G, La Manna P, Musto P, Mensitieri G, Scherillo G. Local Structure and Dynamics of Water Absorbed in Poly(ether imide): A Hydrogen Bonding Anatomy. J Phys Chem B 2017; 121:3162-3176. [PMID: 28335602 DOI: 10.1021/acs.jpcb.7b00992] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hydrogen bonding (HB) interactions play a major role in determining the behavior of macromolecular systems absorbing water. In fact, functional and structural properties of polymer-water mixtures are affected by the amount and type of these interactions. This contribution aims at a molecular level understanding of the interactional scenario for the technologically relevant case of the poly(ether imide)-water system. The problem has been tackled by combining different experimental and theoretical approaches which, taken together, provide a comprehensive physical picture. Relevant experimental data were gathered by in situ FTIR spectroscopy, while molecular dynamics (MD) and statistical thermodynamics approaches were used as modeling theoretical tools. It was found that, among the possible configurations, some are strongly prevailing. In particular, water molecules preferentially establish water bridges with two carbonyl groups of the same PEI repeating unit. Water self-interactions were also detected, giving rise to a "second shell" species in the prevalent form of dimers. The population of the different water species was evaluated spectroscopically, and a remarkable agreement with theoretical predictions was found.
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Affiliation(s)
- Antonio de Nicola
- Department of Chemistry and Biology "Adolfo Zambelli", University of Salerno , Via Giovanni Paolo II, 132, 84084 Fisciano (SA), Italy
| | - Andrea Correa
- Department of Chemical Sciences, Federico II University of Naples Via Cintia , Complesso Monte S. Angelo, 80126 Napoli, Italy
| | - Giuseppe Milano
- Department of Chemistry and Biology "Adolfo Zambelli", University of Salerno , Via Giovanni Paolo II, 132, 84084 Fisciano (SA), Italy.,Institute on Polymers, Composites and Biomaterials, National Research Council of Italy , Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
| | - Pietro La Manna
- Institute on Polymers, Composites and Biomaterials, National Research Council of Italy , Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
| | - Pellegrino Musto
- Institute on Polymers, Composites and Biomaterials, National Research Council of Italy , Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy
| | - Giuseppe Mensitieri
- Institute on Polymers, Composites and Biomaterials, National Research Council of Italy , Via Campi Flegrei 34, 80078 Pozzuoli (NA), Italy.,Department of Chemical, Materials and Production Engineering, University of Naples Federico II , Piazzale Tecchio 80, 80125 Naples, Italy
| | - Giuseppe Scherillo
- Department of Chemical, Materials and Production Engineering, University of Naples Federico II , Piazzale Tecchio 80, 80125 Naples, Italy
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39
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Liu L, Lotze S, Bakker HJ. Vibrational and structural relaxation of hydrated protons in Nafion membranes. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2016.10.062] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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40
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Abstract
In this comprehensive review, recent progress and developments on perfluorinated sulfonic-acid (PFSA) membranes have been summarized on many key topics. Although quite well investigated for decades, PFSA ionomers' complex behavior, along with their key role in many emerging technologies, have presented significant scientific challenges but also helped create a unique cross-disciplinary research field to overcome such challenges. Research and progress on PFSAs, especially when considered with their applications, are at the forefront of bridging electrochemistry and polymer (physics), which have also opened up development of state-of-the-art in situ characterization techniques as well as multiphysics computation models. Topics reviewed stem from correlating the various physical (e.g., mechanical) and transport properties with morphology and structure across time and length scales. In addition, topics of recent interest such as structure/transport correlations and modeling, composite PFSA membranes, degradation phenomena, and PFSA thin films are presented. Throughout, the impact of PFSA chemistry and side-chain is also discussed to present a broader perspective.
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Affiliation(s)
- Ahmet Kusoglu
- Energy Conversion Group, Energy Technologies Area, Lawrence Berkeley National Laboratory , 1 Cyclotron Road, MS70-108B, Berkeley, California 94720, United States
| | - Adam Z Weber
- Energy Conversion Group, Energy Technologies Area, Lawrence Berkeley National Laboratory , 1 Cyclotron Road, MS70-108B, Berkeley, California 94720, United States
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41
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Kabbe G, Dreßler C, Sebastiani D. Proton mobility in aqueous systems: combining ab initio accuracy with millisecond timescales. Phys Chem Chem Phys 2017; 19:28604-28609. [DOI: 10.1039/c7cp05632j] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Development of a combined molecular dynamics/kinetic Monte Carlo scheme for the modeling of excess charge transport in water.
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Affiliation(s)
- Gabriel Kabbe
- Institute of Chemistry
- Martin-Luther-University Halle-Wittenberg
- 06120 Halle
- Germany
| | - Christian Dreßler
- Institute of Chemistry
- Martin-Luther-University Halle-Wittenberg
- 06120 Halle
- Germany
| | - Daniel Sebastiani
- Institute of Chemistry
- Martin-Luther-University Halle-Wittenberg
- 06120 Halle
- Germany
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42
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Hori Y, Ida T, Mizuno M. Potential energy construction in the diabatic picture for quantum mechanical rate constants of intermolecular proton transfer. Phys Chem Chem Phys 2017. [DOI: 10.1039/c7cp03024j] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We propose a simple method for potential construction in the diabatic picture and the estimation of thermal rate constants for intermolecular proton transfer reactions using quantum dynamics simulations carried out on the constructed potentials.
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Affiliation(s)
- Yuta Hori
- Chemistry Course
- Division of Material Chemistry
- Graduate School of Natural Science and Technology
- Kanazawa University
- Kanazawa 920-1192
| | - Tomonori Ida
- Chemistry Course
- Division of Material Chemistry
- Graduate School of Natural Science and Technology
- Kanazawa University
- Kanazawa 920-1192
| | - Motohiro Mizuno
- Chemistry Course
- Division of Material Chemistry
- Graduate School of Natural Science and Technology
- Kanazawa University
- Kanazawa 920-1192
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43
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Schalenbach M, Lueke W, Lehnert W, Stolten D. The influence of water channel geometry and proton mobility on the conductivity of Nafion®. Electrochim Acta 2016. [DOI: 10.1016/j.electacta.2016.08.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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44
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McDaniel JG, Yethiraj A. Importance of hydrophobic traps for proton diffusion in lyotropic liquid crystals. J Chem Phys 2016; 144:094705. [DOI: 10.1063/1.4943131] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Jesse G. McDaniel
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - Arun Yethiraj
- Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
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45
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Chen C, Tse YLS, Lindberg GE, Knight C, Voth GA. Hydroxide Solvation and Transport in Anion Exchange Membranes. J Am Chem Soc 2016; 138:991-1000. [DOI: 10.1021/jacs.5b11951] [Citation(s) in RCA: 167] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Chen Chen
- Department
of Chemistry, James Franck Institute, Institute for Biophysical Dynamics,
and Computation Institute, The University of Chicago, Chicago, Illinois 60637, United States
- College
of Chemistry and Molecular Sciences, Hubei Key Lab of Electrochemical
Power Sources, Wuhan University, Wuhan 430072, China
| | - Ying-Lung Steve Tse
- Department
of Chemistry, James Franck Institute, Institute for Biophysical Dynamics,
and Computation Institute, The University of Chicago, Chicago, Illinois 60637, United States
| | - Gerrick E. Lindberg
- Department
of Chemistry and Biochemistry, Northern Arizona University, Flagstaff, Arizona 86011, United States
| | - Chris Knight
- Leadership
Computing Facility, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Gregory A. Voth
- Department
of Chemistry, James Franck Institute, Institute for Biophysical Dynamics,
and Computation Institute, The University of Chicago, Chicago, Illinois 60637, United States
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46
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Lee MT, Vishnyakov A, Neimark AV. Coarse-grained model of water diffusion and proton conductivity in hydrated polyelectrolyte membrane. J Chem Phys 2016; 144:014902. [DOI: 10.1063/1.4938271] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ming-Tsung Lee
- Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854-8058, USA
| | - Aleksey Vishnyakov
- Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854-8058, USA
| | - Alexander V. Neimark
- Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, 98 Brett Road, Piscataway, New Jersey 08854-8058, USA
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47
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Mabuchi T, Fukushima A, Tokumasu T. A modified two-state empirical valence bond model for proton transport in aqueous solutions. J Chem Phys 2015; 143:014501. [DOI: 10.1063/1.4926394] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Takuya Mabuchi
- Graduate School of Engineering, Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Akinori Fukushima
- Institute of Fluid Science, Tohoku University, Sendai, Miyagi 980-8577, Japan
| | - Takashi Tokumasu
- Institute of Fluid Science, Tohoku University, Sendai, Miyagi 980-8577, Japan
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48
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Allen FI, Comolli LR, Kusoglu A, Modestino MA, Minor AM, Weber AZ. Morphology of Hydrated As-Cast Nafion Revealed through Cryo Electron Tomography. ACS Macro Lett 2015; 4:1-5. [PMID: 35596390 DOI: 10.1021/mz500606h] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Nafion is an ion-containing random copolymer used as a solid electrolyte in many electrochemical applications thanks to its remarkable ionic conductivity and mechanical stability. Understanding the mechanism of ion transport in Nafion, which depends strongly on hydration, therefore requires a complete picture of its morphology in dry and hydrated form. Here we report on a nanoscale study of dry versus hydrated as-cast 100 nm Nafion membranes using analytical transmission electron microscopy (TEM) and cryogenic TEM tomography, respectively. For the dry membrane, spherical clusters ∼3.5 nm in diameter corresponding to the hydrophilic sulfonic-acid-containing phase are identified. In contrast, cryo TEM tomography of the hydrated membrane reveals an interconnected channel-type network, with a domain spacing of ∼5 nm, and presents the first nanoscale 3D views of the internal structure of hydrated Nafion obtained by a direct-imaging approach.
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Affiliation(s)
- Frances I. Allen
- Department of Materials Science and Engineering and ⊥Department of Chemical
and Biomolecular
Engineering, University of California, Berkeley, California 94720, United States
- National Center for Electron Microscopy, Molecular
Foundry, §Life
Sciences Division, and ∥Environmental
Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Luis R. Comolli
- Department of Materials Science and Engineering and ⊥Department of Chemical
and Biomolecular
Engineering, University of California, Berkeley, California 94720, United States
- National Center for Electron Microscopy, Molecular
Foundry, §Life
Sciences Division, and ∥Environmental
Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Ahmet Kusoglu
- Department of Materials Science and Engineering and ⊥Department of Chemical
and Biomolecular
Engineering, University of California, Berkeley, California 94720, United States
- National Center for Electron Microscopy, Molecular
Foundry, §Life
Sciences Division, and ∥Environmental
Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Miguel A. Modestino
- Department of Materials Science and Engineering and ⊥Department of Chemical
and Biomolecular
Engineering, University of California, Berkeley, California 94720, United States
- National Center for Electron Microscopy, Molecular
Foundry, §Life
Sciences Division, and ∥Environmental
Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Andrew M. Minor
- Department of Materials Science and Engineering and ⊥Department of Chemical
and Biomolecular
Engineering, University of California, Berkeley, California 94720, United States
- National Center for Electron Microscopy, Molecular
Foundry, §Life
Sciences Division, and ∥Environmental
Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Adam Z. Weber
- Department of Materials Science and Engineering and ⊥Department of Chemical
and Biomolecular
Engineering, University of California, Berkeley, California 94720, United States
- National Center for Electron Microscopy, Molecular
Foundry, §Life
Sciences Division, and ∥Environmental
Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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49
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Liu L, Bakker HJ. Vibrational excitation induced proton transfer in hydrated Nafion membranes. J Phys Chem B 2015; 119:2628-37. [PMID: 25506744 DOI: 10.1021/jp508862t] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We study the energy relaxation and structural relaxation dynamics of hydrated protons in Nafion membranes at different hydration levels using femtosecond infrared transient absorption spectroscopy. At low hydration levels we observe that the excitation of the proton vibration of an Eigen-like proton hydration structure leads to a structural relaxation process in which the Eigen-like structure evolves to a Zundel-like proton hydration structure. This reorganization leads to a transfer of the proton charge and closely follows the mechanism of infrared-induced adiabatic proton transfer that has been proposed by S. Hammes-Schiffer, J. T. Hynes, and others. At high hydration levels, the spectral dynamics are dominated by vibrational energy relaxation and subsequent cooling of the proton hydration structures and the surrounding water molecules. Using a kinetic analysis of the transient spectral data, we determine the rates of proton transfer, vibrational energy relaxation, and cooling as a function of hydration level. We find that infrared-induced proton transfer occurs at all hydration levels but becomes less observable at high hydration levels due to the increasingly dominant influence of the vibrational energy relaxation.
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Affiliation(s)
- Liyuan Liu
- FOM Institute for Atomic and Molecular Physics, Science Park 104, 1098 XG Amsterdam, The Netherlands
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50
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Daly KB, Panagiotopoulos AZ, Debenedetti PG, Benziger JB. Viscosity of Nafion Oligomers as a Function of Hydration and Counterion Type: A Molecular Dynamics Study. J Phys Chem B 2014; 118:13981-91. [DOI: 10.1021/jp509061z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kevin B. Daly
- Department
of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | | | - Pablo G. Debenedetti
- Department
of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Jay B. Benziger
- Department
of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544, United States
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