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Ma L, Zhong Z, Hu J, Qing L, Jiang J. Long-Lived Weak Ion Pairs in Ionic Liquids: An Insight from All-Atom Molecular Dynamics Simulations. J Phys Chem B 2023. [PMID: 37262343 DOI: 10.1021/acs.jpcb.3c01559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The microstructure and local dynamics of ions in room-temperature ionic liquids (RTILs) have drawn a lot of attention due to their extensive potential applications in numerous fields. It is well-known that the widely used definitions of ion pairs (IPs) cannot reflect the full picture of RTILs. In this study, we find a universal residence time (τMR), which is regardless of the number of counterions in the first solvation shell in RTILs. Inspired by this, we propose a weak IP (WIP) model from a spatiotemporal perspective and demonstrate that the WIPs are long-lived and that their lifetimes obey a log-normal distribution, which is different from the literature. In addition, the electrostatic interactions are the main factors in the formation of WIPs, and the reorientations of ions are vital to the ruptures of WIPs. This research provides a new perspective for understanding the microstructural and dynamical properties of RTILs.
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Affiliation(s)
- Linbo Ma
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Zhixuan Zhong
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Junbao Hu
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Leying Qing
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Jian Jiang
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
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2
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Moon J, Kang H. Effect of cation alkyl chain length on 3-sulfopropylmethacrylate-based draw solutes having lower critical solution temperature. RSC Adv 2023; 13:8291-8298. [PMID: 36926002 PMCID: PMC10011973 DOI: 10.1039/d2ra08068k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Accepted: 03/07/2023] [Indexed: 03/16/2023] Open
Abstract
We investigated the effect of change in alkyl chain length of cation in tributylalkylphosphonium 3-sulfopropyl methacrylate ([P444#][C3S], # = 4, 6, and 8) ionic liquids (ILs) on their osmolality and recovery properties as the draw solute in the forward osmosis (FO) process. The ILs aqueous solutions exhibited a characteristic of the lower critical solution temperature (LCST)-type phase separation, which allowed for the easy recovery of the draw solute or clean water from the diluted draw solution. The LCSTs of 31, 26, 22, and 18 °C were obtained from 2.5, 5.0, 7.5, and 10.0 wt% aqueous solutions of [P4446][C3S]. When deionized water, 2000 ppm NaCl solution, and 10.0 wt% orange juice aqueous solution were used as feed solution, the water fluxes of the aqueous [P4446][C3S] solutions were approximately 4.49, 3.87, and 1.55 LMH, respectively, in the active layer facing the draw solution mode at 7.5 wt% of draw solution. This study demonstrates the applicability of a thermoresponsive ionic structure material as a draw solute for the FO process.
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Affiliation(s)
- Jihyeon Moon
- BK-21 Four Graduate Program, Department of Chemical Engineering, Dong-A University 37 Nakdong-Daero 550 Beon-gil, Saha-gu Busan 49315 Republic of Korea +82 51 200 7728 +82 51 200 7720
| | - Hyo Kang
- BK-21 Four Graduate Program, Department of Chemical Engineering, Dong-A University 37 Nakdong-Daero 550 Beon-gil, Saha-gu Busan 49315 Republic of Korea +82 51 200 7728 +82 51 200 7720
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3
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Moon J, Kang H. Anion Effect on Forward Osmosis Performance of Tetrabutylphosphonium-Based Draw Solute Having a Lower Critical Solution Temperature. MEMBRANES 2023; 13:211. [PMID: 36837713 PMCID: PMC9959785 DOI: 10.3390/membranes13020211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 02/01/2023] [Accepted: 02/07/2023] [Indexed: 06/18/2023]
Abstract
The applicability of ionic liquids (ILs) as the draw solute in a forward osmosis (FO) system was investigated through a study on the effect of the structural change of the anion on the FO performance. This study evaluated ILs composed of tetrabutylphosphonium cation ([P4444]+) and benzenesulfonate anion ([BS]-), para-position alkyl-substituted benzenesulfonate anions (p-methylbenzenesulfonate ([MBS]-) and p-ethylbenzenesulfonate ([EBS-]), and methanesulfonate anion ([MS]-). The analysis of the thermo-responsive properties suggested that the [P4444][MBS] and [P4444][EBS] ILs have lower critical solution temperatures (LCSTs), which play a beneficial role in terms of the reusability of the draw solute from the diluted draw solutions after the water permeation process. At 20 wt% of an aqueous solution, the LCSTs of [P4444][MBS] and [P4444][EBS] were approximately 36 °C and 25 °C, respectively. The water flux and reverse solute flux of the [P4444][MBS] aqueous solution with higher osmolality than [P4444][EBS] were 7.36 LMH and 5.89 gMH in the active-layer facing the draw solution (AL-DS) mode at osmotic pressure of 25 atm (20 wt% solution), respectively. These results indicate that the [P4444]+-based ionic structured materials with LCST are practically advantageous for application as draw solutes.
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Affiliation(s)
| | - Hyo Kang
- Correspondence: ; Tel.: +82-51-200-7720; Fax: +82-51-200-7728
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4
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Moon J, Seo K, Kang H. Effect of the Structural Changes in a Styrenesulfonate-Based Draw Solute Having a Lower Critical Solution Temperature for the Forward Osmosis Process. Ind Eng Chem Res 2022. [DOI: 10.1021/acs.iecr.2c02877] [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]
Affiliation(s)
- Jihyeon Moon
- BK-21 Four Graduate Program, Department of Chemical Engineering, Dong-A University, 37 Nakdong-Daero 550 Beon-Gil, Saha-Gu, Busan49315, Republic of Korea
| | - Kyutae Seo
- BK-21 Four Graduate Program, Department of Chemical Engineering, Dong-A University, 37 Nakdong-Daero 550 Beon-Gil, Saha-Gu, Busan49315, Republic of Korea
| | - Hyo Kang
- BK-21 Four Graduate Program, Department of Chemical Engineering, Dong-A University, 37 Nakdong-Daero 550 Beon-Gil, Saha-Gu, Busan49315, Republic of Korea
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5
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Kong J, Liu L, Li X, Yang Y, Chen X, Fei Y, Xu L, Chen Z. Dimethylthioformamide-derived ionic liquids: Synthesis, characterization and application as supercapacitor electrolyte. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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6
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7
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Li DD, Li EC, Yang YR, Wang XD, Feng G. Structure and Capacitance of Electrical Double Layers in Tricationic Ionic Liquids with Organic Solvents. J Phys Chem B 2021; 125:12753-12762. [PMID: 34766766 DOI: 10.1021/acs.jpcb.1c04978] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Tricationic ionic liquid (TIL) electrolytes have been successfully employed in supercapacitors with graphene electrodes, but the low power density of the TILs-based supercapacitors caused by strong cations-anions associations requires enhancement by adding organic solvents to the liquid. In this paper, the role of the solvents acetonitrile (ACN) and ethylene carbonate (EC) on the ion diffusion, the conductivity of the TIL [C6(mim)3](Tf2N)3, and the structures and the capacitances of the electrical double layers (EDLs) in TIL/ACN and TIL/EC electrolytes were probed by molecular dynamics (MD) simulations. The results indicate that adding organic solvents to the liquid significantly reduces interactions between ions, thereby greatly improving the ion diffusion coefficients and the conductivity of the TIL, and the maximum conductivity is found at the 0.55 M TIL/ACN electrolyte concentration. Moreover, the reduced packing of counterions and the strong expulsion of coions near charged electrodes are observed in the organic electrolytes, especially in the TIL/EC electrolyte. Further analyses on EDLs affirm that the asymmetric camel-shaped differential capacitance-voltage (C-V) curve in the pure TIL electrolyte is weakly changed by the solvent ACN or EC. Besides, the EDL capacitance in the TIL-based hybrid electrolytes is improved slightly by the organic solvents. Comparing the integral capacitances in TIL/ACN and TIL/EC with different solvent contents, it is found that reducing the solvent polarity may be more beneficial to promote the EDL capacitance. Comprehensively, in this work, the 0.55 M TIL/ACN electrolyte is the optimal choice for the high-performance supercapacitor. Hence, solvating TIL electrolytes in supercapacitors by suitable solvents can effectively enhance the power density without compromising energy density.
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Affiliation(s)
- Dan-Dan Li
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing, 102206, China.,Research Center of Engineering Thermophysics, North China Electric Power University, Beijing, 102206, China
| | - Er-Chao Li
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing, 102206, China.,Research Center of Engineering Thermophysics, North China Electric Power University, Beijing, 102206, China
| | - Yan-Ru Yang
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing, 102206, China.,Research Center of Engineering Thermophysics, North China Electric Power University, Beijing, 102206, China
| | - Xiao-Dong Wang
- State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing, 102206, China.,Research Center of Engineering Thermophysics, North China Electric Power University, Beijing, 102206, China
| | - Guang Feng
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China
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8
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Fei Y, Chen Z, Zhang J, Yu M, Kong J, Wu Z, Cao J, Zhang J. Thiazolium-based ionic liquids: Synthesis, characterization and physicochemical properties. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.117553] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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9
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Wang YL, Li B, Sarman S, Mocci F, Lu ZY, Yuan J, Laaksonen A, Fayer MD. Microstructural and Dynamical Heterogeneities in Ionic Liquids. Chem Rev 2020; 120:5798-5877. [PMID: 32292036 PMCID: PMC7349628 DOI: 10.1021/acs.chemrev.9b00693] [Citation(s) in RCA: 192] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Indexed: 12/11/2022]
Abstract
Ionic liquids (ILs) are a special category of molten salts solely composed of ions with varied molecular symmetry and charge delocalization. The versatility in combining varied cation-anion moieties and in functionalizing ions with different atoms and molecular groups contributes to their peculiar interactions ranging from weak isotropic associations to strong, specific, and anisotropic forces. A delicate interplay among intra- and intermolecular interactions facilitates the formation of heterogeneous microstructures and liquid morphologies, which further contributes to their striking dynamical properties. Microstructural and dynamical heterogeneities of ILs lead to their multifaceted properties described by an inherent designer feature, which makes ILs important candidates for novel solvents, electrolytes, and functional materials in academia and industrial applications. Due to a massive number of combinations of ion pairs with ion species having distinct molecular structures and IL mixtures containing varied molecular solvents, a comprehensive understanding of their hierarchical structural and dynamical quantities is of great significance for a rational selection of ILs with appropriate properties and thereafter advancing their macroscopic functionalities in applications. In this review, we comprehensively trace recent advances in understanding delicate interplay of strong and weak interactions that underpin their complex phase behaviors with a particular emphasis on understanding heterogeneous microstructures and dynamics of ILs in bulk liquids, in mixtures with cosolvents, and in interfacial regions.
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Affiliation(s)
- Yong-Lei Wang
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Bin Li
- School
of Chemical Engineering and Technology, Sun Yat-sen University, Zhuhai 519082, P. R. China
| | - Sten Sarman
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Francesca Mocci
- Department
of Chemical and Geological Sciences, University
of Cagliari, I-09042 Monserrato, Italy
| | - Zhong-Yuan Lu
- State
Key Laboratory of Supramolecular Structure and Materials, Institute
of Theoretical Chemistry, Jilin University, Changchun 130021, P. R. China
| | - Jiayin Yuan
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Aatto Laaksonen
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
- State
Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 210009, P. R. China
- Centre of
Advanced Research in Bionanoconjugates and Biopolymers, Petru Poni Institute of Macromolecular Chemistry Aleea Grigore Ghica-Voda, 41A, 700487 Iasi, Romania
- Department
of Engineering Sciences and Mathematics, Division of Energy Science, Luleå University of Technology, SE-97187 Luleå, Sweden
| | - Michael D. Fayer
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
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10
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Chen M, Feng G, Qiao R. Water-in-salt electrolytes: An interfacial perspective. Curr Opin Colloid Interface Sci 2020. [DOI: 10.1016/j.cocis.2019.12.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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11
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Guchhait B, Tibbetts CA, Tracy KM, Luther BM, Krummel AT. Ultrafast vibrational dynamics of a trigonal planar anionic probe in ionic liquids (ILs): A two-dimensional infrared (2DIR) spectroscopic investigation. J Chem Phys 2020; 152:164501. [PMID: 32357764 DOI: 10.1063/1.5141751] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A major impediment limiting the widespread application of ionic liquids (ILs) is their high shear viscosity. Incorporation of a tricyanomethanide (TCM-) anion in ILs leads to low shear viscosity and improvement of several characteristics suitable for large scale applications. However, properties including interactions of TCM- with the local environment and dynamics of TCM- have not been thoroughly investigated. Herein, we have studied the ultrafast dynamics of TCM- in several imidazolium ILs using linear IR and two-dimensional infrared spectroscopy techniques. The spectral diffusion dynamics of the CN stretching modes of TCM- in all ILs exhibit a nonexponential behavior with a short time component of ∼2 ps and a long time component spanning ∼9 ps to 14 ps. The TCM- vibrational probe reports a significantly faster relaxation of ILs compared to those observed previously using linear vibrational probes, such as thiocyanate and selenocyanate. Our results indicate a rapid relaxation of the local ion-cage structure embedding the vibrational probe in the ILs. The faster relaxation suggests that the lifetime of the local ion-cage structure decreases in the presence of TCM- in the ILs. Linear IR spectroscopic results show that the hydrogen-bonding interaction between TCM- and imidazolium cations in ILs is much weaker. Shorter ion-cage lifetimes together with weaker hydrogen-bonding interactions account for the low shear viscosity of TCM- based ILs compared to commonly used ILs. In addition, this study demonstrates that TCM- can be used as a potential vibrational reporter to study the structure and dynamics of ILs and other molecular systems.
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Affiliation(s)
- Biswajit Guchhait
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Clara A Tibbetts
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Kathryn M Tracy
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Bradley M Luther
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Amber T Krummel
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
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12
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Munteshari O, Borenstein A, DeBlock RH, Lau J, Whang G, Zhou Y, Likitchatchawankun A, Kaner RB, Dunn B, Pilon L. In Operando Calorimetric Measurements for Activated Carbon Electrodes in Ionic Liquid Electrolytes under Large Potential Windows. CHEMSUSCHEM 2020; 13:1013-1026. [PMID: 31808623 DOI: 10.1002/cssc.201903011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2019] [Revised: 12/04/2019] [Indexed: 06/10/2023]
Abstract
This study aims to investigate the effect of the potential window on heat generation in carbon-based electrical double layer capacitors (EDLCs) with ionic-liquid (IL)-based electrolytes using in operando calorimetry. The EDLCs consisted of two identical activated-carbon electrodes with either neat 1-butyl-1-methylpyrrolidinium bis(trifluoromethane-sulfonyl)imide ([Pyr14 ][TFSI]) electrolyte or 1.0 m [Pyr14 ][TFSI] in propylene carbonate (PC) as electrolyte. The instantaneous heat generation rate at each electrode was measured under galvanostatic cycling for different potential windows ranging from 1 to 4 V. First, the heat generation rates at the positive and negative electrodes differed significantly in neat IL owing to the differences in the ion sizes and diffusion coefficients. However, these differences were minimized when the IL was diluted in PC. Second, for EDLC in neat [Pyr14 ][TFSI] at high potential window (4 V), a pronounced endothermic peak was observed at the beginning of the charging step at the positive electrode owing to TFSI- intercalation in the activated carbon. On the other hand, for EDLC in 1.0 m [Pyr14 ][TFSI] in PC at potential window above 3 V, an endothermic peak was observed only at the negative electrode owing to the decomposition of PC. Third, for both neat and diluted [Pyr14 ][TFSI] electrolytes, the irreversible heat generation rate increased with increasing potential window and exceeded Joule heating. This was attributed to the effect of potential-dependent charge redistribution resistance. A further increase in the irreversible heat generation rate was observed for the largest potential windows owing to the degradation of the PC solvent. Finally, for both types of electrolyte, the reversible heat generation rate increased with increasing potential window because of the increase in the amount of ion adsorbed/desorbed at the electrode/electrolyte interface.
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Affiliation(s)
- Obaidallah Munteshari
- Mechanical and Aerospace Engineering Department, Henry Samueli School of Engineering and Applied Science, University of California, Los Angeles, CA, 90095, USA
- Mechanical Engineering Department, King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, 31261, Saudi Arabia
| | - Arie Borenstein
- Chemistry Department, Ariel University, Ariel, Israel
- Chemistry and Biochemistry Department, University of California, Los Angeles, California, 90095, USA
| | - Ryan H DeBlock
- Materials Science and Engineering Department, Henry Samueli School of Engineering and Applied Science, University of California, Los Angeles, CA, 90095, USA
| | - Jonathan Lau
- Materials Science and Engineering Department, Henry Samueli School of Engineering and Applied Science, University of California, Los Angeles, CA, 90095, USA
| | - Grace Whang
- Materials Science and Engineering Department, Henry Samueli School of Engineering and Applied Science, University of California, Los Angeles, CA, 90095, USA
| | - Yucheng Zhou
- Mechanical and Aerospace Engineering Department, Henry Samueli School of Engineering and Applied Science, University of California, Los Angeles, CA, 90095, USA
| | - Ampol Likitchatchawankun
- Mechanical and Aerospace Engineering Department, Henry Samueli School of Engineering and Applied Science, University of California, Los Angeles, CA, 90095, USA
| | - Richard B Kaner
- Chemistry and Biochemistry Department, University of California, Los Angeles, California, 90095, USA
- Materials Science and Engineering Department, Henry Samueli School of Engineering and Applied Science, University of California, Los Angeles, CA, 90095, USA
- California NanoSystems Institute, University of California, Los Angeles, CA, 90095, USA
| | - Bruce Dunn
- Materials Science and Engineering Department, Henry Samueli School of Engineering and Applied Science, University of California, Los Angeles, CA, 90095, USA
- California NanoSystems Institute, University of California, Los Angeles, CA, 90095, USA
| | - Laurent Pilon
- Mechanical and Aerospace Engineering Department, Henry Samueli School of Engineering and Applied Science, University of California, Los Angeles, CA, 90095, USA
- California NanoSystems Institute, University of California, Los Angeles, CA, 90095, USA
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13
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Clark R, von Domaros M, McIntosh AJS, Luzar A, Kirchner B, Welton T. Effect of an external electric field on the dynamics and intramolecular structures of ions in an ionic liquid. J Chem Phys 2019; 151:164503. [PMID: 31675893 DOI: 10.1063/1.5129367] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Simulations of the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide in an external electric field have been performed using a Drude particle polarizable force field. The structure of the ions has been analyzed, with close attention paid to the configurations of the ions. The "charge arm" concept is used to explain certain changes of these configurations that would be difficult to rationalize otherwise, e.g., trans → cis isomerization of the bis(trifluoromethylsulfonyl)imide anion and extension of the alkyl chain of the cation. It has also been shown that the ions orient themselves so that their charge arms align with and stretch out along the field, and these effects occur at lower external electric field strengths than cause a change in the inherent diffusion of the ions. The dynamics of the system parallel and perpendicular to the field were analyzed, and it was found that the applied field affected the diffusion normal to the field. This is explained as a secondary effect of a change in the ion cage formed by the surrounding counterions of a given ion in the ionic liquid. The breakdown of the ion cages was rationalized by correlating changes to the inherent diffusion of the ions with other changes to the diffusion and bulk structure of the liquid, as well as considering the average forces on the ions compared to the force the ions would be expected to experience in an electric field. Parallel to the field, a drift was observed at every electric field studied. In electric fields with no changes to the ion cage structure, the relationship between the drift and electric field was found to be linear, becoming nonlinear as the ion cage structure breaks down.
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Affiliation(s)
- Ryan Clark
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, United Kingdom
| | - Michael von Domaros
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstr. 4+6, D-53115 Bonn, Germany
| | - Alastair J S McIntosh
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, United Kingdom
| | - Alenka Luzar
- Department of Chemistry, Virginia Commonwealth University, 1001 West Main St., Richmond, Virginia 23284-2006, USA
| | - Barbara Kirchner
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstr. 4+6, D-53115 Bonn, Germany
| | - Tom Welton
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, United Kingdom
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14
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Sha M, Ma X, Li N, Luo F, Zhu G, Fayer MD. Dynamical properties of a room temperature ionic liquid: Using molecular dynamics simulations to implement a dynamic ion cage model. J Chem Phys 2019; 151:154502. [PMID: 31640381 DOI: 10.1063/1.5126231] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The transport behavior of ionic liquids (ILs) is pivotal for a variety of applications, especially when ILs are used as electrolytes. Many aspects of the transport dynamics of ILs remain to be understood. Here, a common ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BmimNTf2), was studied with molecular dynamics simulations. The results show that BmimNTf2 displays typical structural relaxation, subdiffusive behavior, and a breakdown of the Stokes-Einstein diffusion relation as in glass-forming liquids. In addition, the simulations show that the translational dynamics, reorientation dynamics, and structural relaxation dynamics are well described by the Vogel-Fulcher-Tammann equation like fragile glass forming liquids. Building on previous work that employed ion cage models, it was found that the diffusion dynamics of the cations and anions were well described by a hopping process random walk where the step time is the ion cage lifetime obtained from the cage correlation function. Detailed analysis of the ion cage structures indicated that the electrostatic potential energy of the ion cage dominates the diffusion dynamics of the caged ion. The ion orientational relaxation dynamics showed that ion reorientation is a necessary step for ion cage restructuring. The dynamic ion cage model description of ion diffusion presented here may have implications for designing ILs to control their transport behavior.
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Affiliation(s)
- Maolin Sha
- Department of Physics and Materials Engineering, Hefei Normal University, Hefei 230061, China
| | - Xiaohang Ma
- Department of Physics and Materials Engineering, Hefei Normal University, Hefei 230061, China
| | - Na Li
- Department of Chemistry and Chemical Engineering, Hefei Normal University, Hefei 230061, China
| | - Fabao Luo
- Department of Chemistry and Chemical Engineering, Hefei Normal University, Hefei 230061, China
| | - Guanglai Zhu
- Institute of Atomic and Molecular Physics, Anhui Normal University, Wuhu 241000, China
| | - Michael D Fayer
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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15
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Chien CH, Zhou C, Sing SY, Lopez B, Theodore A, Wu CY, Birky BK. Effects of Relative Humidity on Impregnated Filters Used in Measurement of Airborne Sulfur Dioxide. Ann Work Expo Health 2019; 63:806-813. [PMID: 31278740 DOI: 10.1093/annweh/wxz053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 04/25/2019] [Accepted: 06/08/2019] [Indexed: 11/13/2022] Open
Abstract
Impregnated filters treated with alkali and humectant were first used as collection media to assess occupational exposure to sulfur dioxide (SO2), as outlined in the National Institute for Occupational Safety and Health Method 6004 in 1979. Since then, updated treatment protocols have been proposed with decreased amounts of alkali and glycerol, which claim the same filtering capacity. However, there has been no report on how the collection of SO2 on such impregnated media is influenced by relative humidity (RH). This study investigated the role of glycerol (G) amount on impregnated filters (G2 and G10, referring to 2 and 10% glycerol, respectively) in the collection of SO2 (100 l of 10 ppm at 1 l per minute) under low, medium, and high RHs. The testing results show that RH significantly impacted G2 filters with respect to breakthrough time, capacity, and recovery. At low RH, the 5% breakthrough time was less than 10 min and its recovery was merely 42%; at medium and high RHs, although the recovery was satisfactory, the 5% breakthrough time was still less than 100 min. By contrast, G10 filters illustrated nearly 100% recovery and evaluation by analysis of variance showed no significant effect of RH on recovery. In summary, the current treatment protocol of 2% glycerol leads to a significant underestimation of the exposure to SO2 in a low-RH environment; increasing the glycerol content can be an effective alternative to compensating for the effect of RH.
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Affiliation(s)
- Chih-Hsiang Chien
- Department of Environmental Engineering Sciences, Engineering School of Sustainable Infrastructure and Environment, University of Florida, Gainesville, FL, USA
| | - Chufan Zhou
- Department of Environmental Engineering Sciences, Engineering School of Sustainable Infrastructure and Environment, University of Florida, Gainesville, FL, USA
| | - Simon Yang Sing
- Department of Environmental Engineering Sciences, Engineering School of Sustainable Infrastructure and Environment, University of Florida, Gainesville, FL, USA
| | - Benjamin Lopez
- Department of Environmental Engineering Sciences, Engineering School of Sustainable Infrastructure and Environment, University of Florida, Gainesville, FL, USA
| | | | - Chang-Yu Wu
- Department of Environmental Engineering Sciences, Engineering School of Sustainable Infrastructure and Environment, University of Florida, Gainesville, FL, USA
| | - Brian K Birky
- Florida Industrial and Phosphate Research Institute, Bartow, FL, USA
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16
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McDaniel JG, Verma A. On the Miscibility and Immiscibility of Ionic Liquids and Water. J Phys Chem B 2019; 123:5343-5356. [DOI: 10.1021/acs.jpcb.9b02187] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Jesse G. McDaniel
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Archana Verma
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
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17
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Zhao W, Bi S, Zhang C, Rack PD, Feng G. Adding Solvent into Ionic Liquid-Gated Transistor: The Anatomy of Enhanced Gating Performance. ACS APPLIED MATERIALS & INTERFACES 2019; 11:13822-13830. [PMID: 30875194 DOI: 10.1021/acsami.9b03433] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Most studies of ionic liquid (IL)-gated field effect transistors (FETs) focus on the extremely large electric field and capacitance induced in liquid/solid interfaces and correspondingly the significantly enhanced carrier density in semiconductors, which can appreciably improve the gating performance. However, how to boost the switching speed, another key property of gating performance of FETs, has been rarely explored. In this work, the gating performance of molybdenum disulfide (MoS2) FETs, gated by the mixtures of IL/organic solvent (1-butyl-3-methylimidazolium tetrafluoroborate/acetonitrile, [Bmim][BF4]/ACN) at different ion concentrations, is investigated for both dynamic and static properties by a combination of molecular dynamics simulation and resistance network analysis. Results reveal that organic solvent can speed up the IL response time by a factor of about 40 times at the optimal ion concentration of 1.94 M, which is mainly attributed to the increased ionic conductivity of IL via the addition of organic solvent. Meanwhile, the surface charge distribution of MoS2 becomes more homogenous after the addition of organic solvent, which increases the conductivity of MoS2 by up to 2.4 times. Surprisingly, the optimal ion concentration for increased switching speed is nearly the same as that for achieving the highest MoS2 conductivity. Thus, our findings provide a strategy to simultaneously improve the dynamic and static gating performance of IL-gated FETs as well as a modeling technique to screen out the ideal ion concentration.
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Affiliation(s)
- Wei Zhao
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Sheng Bi
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering , Huazhong University of Science and Technology , Wuhan 430074 , China
| | - Cheng Zhang
- Department of Materials Science and Engineering , University of Tennessee , Knoxville , Tennessee 37996 , United States
| | - Philip D Rack
- Department of Materials Science and Engineering , University of Tennessee , Knoxville , Tennessee 37996 , United States
- Center for Nanophase Materials Sciences , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States
| | - Guang Feng
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering , Huazhong University of Science and Technology , Wuhan 430074 , China
- Shenzhen Research Institute of Huazhong University of Science and Technology , Shenzhen 518057 , China
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18
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Bezold F, Roehrer S, Minceva M. Ionic Liquids as Modifying Agents for Protein Separation in Centrifugal Partition Chromatography. Chem Eng Technol 2019. [DOI: 10.1002/ceat.201800369] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Franziska Bezold
- Technical University of Munich; Biothermodynamics; TUM School of Life and Food Sciences Weihenstephan; Maximus-von-Imhof-Forum 2 85354 Freising Germany
| | - Simon Roehrer
- Technical University of Munich; Biothermodynamics; TUM School of Life and Food Sciences Weihenstephan; Maximus-von-Imhof-Forum 2 85354 Freising Germany
| | - Mirjana Minceva
- Technical University of Munich; Biothermodynamics; TUM School of Life and Food Sciences Weihenstephan; Maximus-von-Imhof-Forum 2 85354 Freising Germany
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19
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Viscosity calculation of 1‑ethyl‑3‑methyl‑imidazolium chloride ionic liquids based on three-body potential hydrogen bond model. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.09.035] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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20
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Ma C, Laaksonen A, Liu C, Lu X, Ji X. The peculiar effect of water on ionic liquids and deep eutectic solvents. Chem Soc Rev 2018; 47:8685-8720. [PMID: 30298877 DOI: 10.1039/c8cs00325d] [Citation(s) in RCA: 224] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Ionic liquids (ILs) and deep eutectic solvents (DESs) have been suggested as eco-friendly alternatives to organic solvents. A trace amount of water is often unavoidable as impurity, and water is also added on purpose to reduce their problematically high viscosity and lower their high price. Understanding the distinct effects of water on the properties of ILs/DESs is highly important. In this review, we collect published experimental and theoretical results for IL/DES-H2O systems at varied water concentrations and analyze them. Results from mechanistic studies, thermodynamic modelling and advanced experiments are collected and critically discussed. Six commonly studied IL/DES-H2O systems were selected to map experimental observations onto microscopic results obtained in mechanistic studies. A great variety of distinct contours of the excess properties can be observed over the entire compositional range, indicating that the properties of IL/DES-H2O systems are highly unpredictable. Mechanistic studies clearly demonstrate that the added H2O rapidly changes the heterogeneous 3D structures of pure ILs/DESs, leading to very different properties and behaviour. There are similarities between aqueous electrolytes and IL/DES solutions but the bulky and asymmetric organic cations in ILs/DESs do not conform to the standard salt dissolution and hydration concepts. Thermodynamic modelling previously assumes ILs/DESs to be either a neutral ion-pair or completely dissociated ions, neglecting specific ion hydration effects. A new conceptual framework is suggested for thermodynamic modelling of IL/DES-H2O binary systems to enable new technologies for their practical applications.
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Affiliation(s)
- Chunyan Ma
- Energy Engineering, Division of Energy Science, Luleå University of Technology, Luleå, 971 87, Sweden.
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21
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McDaniel JG, Son CY. Ion Correlation and Collective Dynamics in BMIM/BF4-Based Organic Electrolytes: From Dilute Solutions to the Ionic Liquid Limit. J Phys Chem B 2018; 122:7154-7169. [DOI: 10.1021/acs.jpcb.8b04886] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jesse G. McDaniel
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States
| | - Chang Yun Son
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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22
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Chen M, Goodwin ZA, Feng G, Kornyshev AA. On the temperature dependence of the double layer capacitance of ionic liquids. J Electroanal Chem (Lausanne) 2018. [DOI: 10.1016/j.jelechem.2017.11.005] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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23
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Lu H, Nordholm S, Woodward CE, Forsman J. Ionic liquid interface at an electrode: simulations of electrochemical properties using an asymmetric restricted primitive model. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:074004. [PMID: 29300174 DOI: 10.1088/1361-648x/aaa524] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We use Monte Carlo simulations of a coarse-grained model to investigate structure and electrochemical behaviours at an electrode immersed in room temperature ionic liquids (RTILs). The simple RTIL model, which we denote the asymmetric restricted primitive model (ARPM), is composed of monovalent hard-sphere ions, all of the same size, in which the charge is asymmetrically placed. Not only the hard-sphere size (d), but also the charge displacement (b), is identical for all species, i.e. the monovalent RTIL ions are fully described by only two parameters (d, b). In earlier work, it was demonstrated that the ARPM can capture typical static RTIL properties in bulk solutions with remarkable accuracy. Here, we investigate its behaviour at an electrode surface. The electrode is assumed to be a perfect conductor and image charge methods are utilized to handle polarization effects. We find that the ARPM of the ionic liquid reproduces typical (static) electrochemical properties of RTILs. Our model predicts a declining differential capacitance with increasing temperature, which is expected from simple physical arguments. We also compare our ARPM, with the corresponding RPM description, at an elevated temperature (1000 K). We conclude that, even though ion pairing occurs in the ARPM system, reducing the concentration of 'free' ions, it is still better able to screen charge than a corresponding RPM melt. Finally, we evaluate the option to coarse-grain the model even further, by treating the fraction of the ions that form ion pairs implicitly, only through the contribution to the dielectric constant of the corresponding dipolar (ion pair) fluid. We conclude that this primitive representation of ion pairing is not able to reproduce the structures and differential capacitances of the system with explicit ion pairs. The main problem seems to be due to a limited dielectric screening in a layer near the electrode surface, resulting from a combination of orientational restrictions and a depleted dipole density.
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Affiliation(s)
- Hongduo Lu
- Theoretical Chemistry, Lund University, PO Box 124, SE-221 00 Lund, Sweden
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24
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Mariani A, Bonomo M, Wu B, Centrella B, Dini D, Castner EW, Gontrani L. Intriguing transport dynamics of ethylammonium nitrate-acetonitrile binary mixtures arising from nano-inhomogeneity. Phys Chem Chem Phys 2018; 19:27212-27220. [PMID: 28975937 DOI: 10.1039/c7cp04592a] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Binary mixtures of ethylammonium nitrate and acetonitrile show interesting properties that originate from the structural and dynamical nano-heterogeneity present in ionic liquids. These effects are most pronounced when the ionic liquid is the minority compound. In this study the transport properties of such mixtures are studied, including viscosity, self-diffusion and conductivity. The results strongly support the presence of structural inhomogeneity and show an interesting composition-dependent behaviour in the mixtures.
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Affiliation(s)
- Alessandro Mariani
- Department of Chemistry, La Sapienza University of Rome, P.le A. Moro 5, 00185 Rome, Italy.
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25
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Driver GW, Huang Y, Laaksonen A, Sparrman T, Wang YL, Westlund PO. Correlated/non-correlated ion dynamics of charge-neutral ion couples: the origin of ionicity in ionic liquids. Phys Chem Chem Phys 2018; 19:4975-4988. [PMID: 28074972 DOI: 10.1039/c6cp05801a] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Proton/fluoride spin-lattice (T1) nuclear magnetic relaxation dispersion (NMRD) measurements of 1-butyl-3-methyl-1H-imidazolium hexafluorophosphate, [C4mim][PF6], have been carried out using high field spectrometers and a fast-field-cycling instrument at proton Larmor frequencies ranging from 10 kHz to 40 MHz, at different temperatures. The NMRD profiles are interpreted by means of a simple relaxation model based on the inter- and intra-ionic dipole-dipole relaxation mechanism. Using an atomic molecular-ion dynamic simulation at 323 K the relevant spin dipole-dipole (DD) correlation functions are calculated. The results indicate that the NMRD profiles can be rationalized using intra- and inter-ionic spin DD interactions, however, anions are mainly modulated by ionic reorientation because of temporary correlations with cations, where modulation by translational diffusion plays a minor role. Reorientational dynamics of charge-neutral ion couples (i.e. [C4mim][PF6]) and [C4mim]+ ions are in the nano-second (ns) time range whereas the reorientation of [PF6]- is characterized by a reorientational correlation time in the pico-second (ps) regime. Based on the NMRD profiles we conclude that the main relaxation mechanism for [PF6]- is due to fast internal reorientational motion, a partially averaged F-F intra- and F-H inter-ionic DD coupling as the anion resides in close proximity to its temporary oppositely charged cation partner. The F-T1-NMRD data display a ns dispersion which is interpreted as being due to correlated reorientational modulations resulting from the H-containing charge-neutral ion couple [C4mim][PF6]. The analysis of ionicity is based on the free anion fraction, f, and it increases with temperature with f → 1 at the highest temperatures investigated. The fraction is obtained from the H-F NMRD profiles as correlated-non-correlated dynamics of the ions. The analysis of T1 relaxation rates of C, H, F and P at high fields cannot generally give the fraction of ions but is consistent with the interpretation based on the NMRD profiles with relaxation contributions due to DD-intra and -inter, CSA-intra (and -inter for C), including spin rotation for P. The investigation has led to a description of the mechanics governing ion transport in the title ionic liquid via identification of transient correlated/non-correlated ion dynamics.
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Affiliation(s)
- G W Driver
- Department of Chemistry, Umea University, SE 90187 Umea, Sweden.
| | - Y Huang
- Department of Chemistry, Umea University, SE 90187 Umea, Sweden.
| | - A Laaksonen
- Department of Chemistry, Umea University, SE 90187 Umea, Sweden.
| | - T Sparrman
- Department of Chemistry, Umea University, SE 90187 Umea, Sweden.
| | - Y-L Wang
- Department of Chemistry, Umea University, SE 90187 Umea, Sweden.
| | - P-O Westlund
- Department of Chemistry, Umea University, SE 90187 Umea, Sweden.
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26
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Yamada SA, Bailey HE, Tamimi A, Li C, Fayer MD. Dynamics in a Room-Temperature Ionic Liquid from the Cation Perspective: 2D IR Vibrational Echo Spectroscopy. J Am Chem Soc 2017; 139:2408-2420. [DOI: 10.1021/jacs.6b12011] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Steven A. Yamada
- Department of Chemistry Stanford University, Stanford, California 94305, United States
| | - Heather E. Bailey
- Department of Chemistry Stanford University, Stanford, California 94305, United States
| | - Amr Tamimi
- Department of Chemistry Stanford University, Stanford, California 94305, United States
| | - Chunya Li
- Department of Chemistry Stanford University, Stanford, California 94305, United States
| | - Michael D. Fayer
- Department of Chemistry Stanford University, Stanford, California 94305, United States
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27
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Zhu G, Kang X, Zhou S, Tang X, Sha M, Cui Z, Xu X. Molecular insight into the microstructure and microscopic dynamics of pyridinium ionic liquids with different alkyl chains based on temperature response. RSC Adv 2017. [DOI: 10.1039/c6ra26866h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
High temperature is advantageous to the aggregation of the polar regions as well as the nonpolar regions of pyridinium ionic liquids.
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Affiliation(s)
- Guanglai Zhu
- Institute of Atomic and Molecular Physics
- Anhui Normal University
- Wuhu 241000
- China
| | - Xianqu Kang
- Institute of Atomic and Molecular Physics
- Anhui Normal University
- Wuhu 241000
- China
| | - Siwen Zhou
- Institute of Atomic and Molecular Physics
- Anhui Normal University
- Wuhu 241000
- China
| | - Xiaoshuan Tang
- Institute of Atomic and Molecular Physics
- Anhui Normal University
- Wuhu 241000
- China
| | - Maolin Sha
- Department of Chemistry and Chemical Engineering
- Hefei Normal University
- Hefei 230061
- China
| | - Zhifeng Cui
- Institute of Atomic and Molecular Physics
- Anhui Normal University
- Wuhu 241000
- China
| | - Xinsheng Xu
- Institute of Atomic and Molecular Physics
- Anhui Normal University
- Wuhu 241000
- China
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28
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Matsubara Y, Grills DC, Koide Y. Experimental Insight into the Thermodynamics of the Dissolution of Electrolytes in Room-Temperature Ionic Liquids: From the Mass Action Law to the Absolute Standard Chemical Potential of a Proton. ACS OMEGA 2016; 1:1393-1411. [PMID: 31457204 PMCID: PMC6640753 DOI: 10.1021/acsomega.6b00129] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Accepted: 12/12/2016] [Indexed: 06/10/2023]
Abstract
Room-temperature ionic liquids (ILs) are a class of nonaqueous solvents that have expanded the realm of modern chemistry, drawing increasing interest over the last few decades, not only in terms of their own unique physical chemistry but also in many applications including organic synthesis, electrochemistry, and biological systems, wherein charged solutes (i.e., electrolytes) often play vital roles. However, our fundamental understanding of the dissolution of an electrolyte in an IL is still rather limited. For example, the activity of a charged species has frequently been assumed to be unity without a clear experimental basis. In this study, we have discussed a standard component-based scheme for the dissolution of an electrolyte in an IL, supported by our observation of ideal Nernstian responses for the reduction of silver and ferrocenium salts in a representative IL, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([emim+][NTf2 -] or [emim+][TFSI-]). Using this scheme, which was also supported by temperature-dependent measurements with ILs having longer alkyl chains in the imidazolium ring, and the solubility of the IL in water, we established the concept of Gibbs transfer energies of "pseudo-single ions" from the IL to conventional neutral molecular solvents (water, acetonitrile, and methanol). This concept, which bridges component- and constituent-based energetics, utilizes an extrathermodynamic assumption, which itself was justified by experimental observations. These energies enable us to eliminate inner potential differences between the IL and molecular solvents (solvent-solvent interactions), that is, on a practical level, conditional liquid junction potential differences, so that we can discuss ion-solvent interactions independently. Specifically, we have examined the standard electrode potential of the ferrocenium/ferrocene redox couple, Fc+/Fc, and the absolute intrinsic standard chemical potential of a proton in [emim+][NTf2 -], finding that the proton is more acidic in the IL than in water by 6.5 ± 0.6 units on the unified pH scale. These results strengthen the progress on the physical chemistry of ions in IL solvent systems on the basis of their activities, providing a rigorous thermodynamic framework.
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Affiliation(s)
- Yasuo Matsubara
- Department
of Material and Life Chemistry, Kanagawa
University, 3-27-1 Rokkakubashi, Kanagawa-ku, Yokohama 221-8686, Japan
| | - David C. Grills
- Chemistry
Division, Brookhaven National Laboratory, P.O. Box 5000, Upton, New
York 11973-5000, United
States
| | - Yoshihiro Koide
- Department
of Material and Life Chemistry, Kanagawa
University, 3-27-1 Rokkakubashi, Kanagawa-ku, Yokohama 221-8686, Japan
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29
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Lu H, Li B, Nordholm S, Woodward CE, Forsman J. Ion pairing and phase behaviour of an asymmetric restricted primitive model of ionic liquids. J Chem Phys 2016; 145:234510. [DOI: 10.1063/1.4972214] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Hongduo Lu
- Theoretical Chemistry, Lund University, P.O. Box 124, S-221 00 Lund, Sweden
| | - Bin Li
- Theoretical Chemistry, Lund University, P.O. Box 124, S-221 00 Lund, Sweden
| | - Sture Nordholm
- Department of Chemistry, The University of Gothenburg, SE-412 96 Göteborg, Sweden
| | - Clifford E. Woodward
- School of Physical, Environmental and Mathematical Sciences, University of New South Wales, Canberra, ACT 2600, Australia
| | - Jan Forsman
- Theoretical Chemistry, Lund University, P.O. Box 124, S-221 00 Lund, Sweden
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30
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Sha M, Liu Y, Dong H, Luo F, Jiang F, Tang Z, Zhu G, Wu G. Origin of heterogeneous dynamics in local molecular structures of ionic liquids. SOFT MATTER 2016; 12:8942-8949. [PMID: 27747361 DOI: 10.1039/c6sm01797e] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Room-temperature ionic liquids (ILs) are generally considered as structurally heterogeneous with inherent polar/apolar phase separation. However, even after a decade of research, local dynamics in the heterogeneous structures of ILs remain neglected. Such local dynamics may influence the ion transport of electrolytes, as well as the reaction rate of solvents. In this study, we performed molecular dynamics simulation to analyze the local dynamics for the structural heterogeneity of ILs. Calculations of the diffusion, reorientation, and association dynamics showed a distinct heterogeneous dynamics between the polar and apolar regions of ILs. Further studies demonstrated that such local dynamic differences originate from local structural heterogeneity. Different energy barriers determine a predominant fast reorientation dynamics in apolar regions and a locally vibrating behavior in polar regions. Additionally, we suggested a new jumping mechanism to clarify the dynamic heterogeneity of ions in the polar regions. The results will help determine the origin of the heterogeneous dynamics in IL local structures and provide a theoretical basis for tuning the dynamic properties of ILs used as electrolytes or reaction solvents.
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Affiliation(s)
- Maolin Sha
- Department of Chemistry and Chemical Engineering, Hefei Normal University, Hefei 230061, China.
| | - Yusheng Liu
- Department of Chemistry and Chemical Engineering, Xuzhou Institute of Technology, Xuzhou 221018, China
| | - Huaze Dong
- Department of Chemistry and Chemical Engineering, Hefei Normal University, Hefei 230061, China.
| | - Fabao Luo
- Department of Chemistry and Chemical Engineering, Hefei Normal University, Hefei 230061, China.
| | - Fangling Jiang
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. B. Box 800-204, Shanghai 201800, China.
| | - Zhongfeng Tang
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. B. Box 800-204, Shanghai 201800, China.
| | - Guanglai Zhu
- Institute of Atomic and Molecular Physics, Anhui Normal University, Wuhu 241000, China
| | - Guozhong Wu
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P. B. Box 800-204, Shanghai 201800, China.
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31
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Zanatta M, Girard AL, Marin G, Ebeling G, dos Santos FP, Valsecchi C, Stassen H, Livotto PR, Lewis W, Dupont J. Confined water in imidazolium based ionic liquids: a supramolecular guest@host complex case. Phys Chem Chem Phys 2016; 18:18297-304. [DOI: 10.1039/c6cp03112a] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Traces of water in some ionic liquids can be regarded as a guest@host supramolecular structure even when diluted in solvents with high dielectric constants.
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Affiliation(s)
- Marcileia Zanatta
- Institute of Chemistry
- UFRGS
- Avenida Bento Gonçalves
- 9500 Porto Alegre
- Brazil
| | - Anne-Lise Girard
- Institute of Chemistry
- UFRGS
- Avenida Bento Gonçalves
- 9500 Porto Alegre
- Brazil
| | - Graciane Marin
- Institute of Chemistry
- UFRGS
- Avenida Bento Gonçalves
- 9500 Porto Alegre
- Brazil
| | - Gunter Ebeling
- Institute of Chemistry
- UFRGS
- Avenida Bento Gonçalves
- 9500 Porto Alegre
- Brazil
| | | | - Chiara Valsecchi
- Institute of Chemistry
- UFRGS
- Avenida Bento Gonçalves
- 9500 Porto Alegre
- Brazil
| | - Hubert Stassen
- Institute of Chemistry
- UFRGS
- Avenida Bento Gonçalves
- 9500 Porto Alegre
- Brazil
| | - Paolo R. Livotto
- Institute of Chemistry
- UFRGS
- Avenida Bento Gonçalves
- 9500 Porto Alegre
- Brazil
| | - William Lewis
- School of Chemistry
- University of Nottingham
- Nottingham
- UK
| | - Jairton Dupont
- Institute of Chemistry
- UFRGS
- Avenida Bento Gonçalves
- 9500 Porto Alegre
- Brazil
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32
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Pal T, Biswas R. Composition Dependence of Dynamic Heterogeneity Time- and Length Scales in [Omim][BF4]/Water Binary Mixtures: Molecular Dynamics Simulation Study. J Phys Chem B 2015; 119:15683-95. [DOI: 10.1021/acs.jpcb.5b08763] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tamisra Pal
- Department of Chemical, Biological
and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098, India
| | - Ranjit Biswas
- Department of Chemical, Biological
and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098, India
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