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Li Q, Zhu G, Liu Z, Xu J. Molecular dynamics simulation studies on the ionic liquid N-butylpyridinium tetrafluoroborate on the gold surface. Heliyon 2024; 10:e32710. [PMID: 38975103 PMCID: PMC11225740 DOI: 10.1016/j.heliyon.2024.e32710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 05/26/2024] [Accepted: 06/07/2024] [Indexed: 07/09/2024] Open
Abstract
The study of solid/liquid interface is of great significance for understanding various phenomena such as the nanostructure of the interface, liquid wetting, crystal growth and nucleation. In this work, the nanostructure of the pyridinium ionic liquid [BPy]BF4 on different gold surfaces was studied by molecular dynamics simulation. The results indicate that the density of the ionic liquids near the gold surface is significantly higher than that in the bulk phase. Cation's tail (the alkyl chain) orients parallel to the surface under all studied conditions. Cation's head (the pyridine ring) orientation varies from parallel to perpendicular, which depends on the temperature and corrugation of the Au(hkl) surface. Interestingly, analysis of simulated mass and number densities revealed that surface corrugation randomizes the cations packing. On smooth Au(111) and Au(100) surfaces, parallel and perpendicular orientations are well distinguished for densely packed cations. While on corrugated Au(110), cations' packing density and order are decreased. Overall, this study explores the adsorption effect of the gold surface on ionic liquids, providing some valuable insights into their behavior on the solid/liquid interface.
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Affiliation(s)
- Qiang Li
- Anhui Province Key Laboratory for Control and Applications of Optoelectronic Information Materials, School of Physics and Electronic Information, Anhui Normal University, Wuhu, 241002, China
- Faculty of Engineering, Anhui Sanlian University, Hefei, 230601, China
| | - Guanglai Zhu
- Anhui Province Key Laboratory for Control and Applications of Optoelectronic Information Materials, School of Physics and Electronic Information, Anhui Normal University, Wuhu, 241002, China
| | - Zhicong Liu
- Anhui Province Key Laboratory for Control and Applications of Optoelectronic Information Materials, School of Physics and Electronic Information, Anhui Normal University, Wuhu, 241002, China
| | - Jianqiang Xu
- Anhui Province Key Laboratory for Control and Applications of Optoelectronic Information Materials, School of Physics and Electronic Information, Anhui Normal University, Wuhu, 241002, China
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2
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Ntim S, Sulpizi M. Differential Capacitance of Ionic Liquid Confined between Metallic Interfaces. J Phys Chem B 2024; 128:1936-1942. [PMID: 38378468 DOI: 10.1021/acs.jpcb.3c08042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
We present here a detailed analysis of the electric double layer at the gold electrode/[BMIM][BF4] interface using a polarizable model for the electrode, based on our recent approach to include image charges [Geada et al. Nat. Commun. 2018, 9, 716]. A double bell (camel) shape is obtained for the differential capacitance, where the inclusion of metal polarization allows for a higher density of ions in the double layer, particularly around the maxima, thereby increasing the capacitance. The charging mechanism differs for the positive and negative electrodes, with counterion adsorption prevailing at the anode and co-ion desorption prevailing at the cathode. The charging mechanism is predominantly governed by the BF4 anions, serving as counterions and co-ions at the anode and cathode, respectively. Within the considered range of potentials, only minor changes are observed in the dynamical properties, specifically in the diffusion coefficients. Notably, it is interesting to observe that bulk properties are restored at a shorter distance from the gold surface in the case of the anode compared to the cathode.
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Affiliation(s)
- Samuel Ntim
- Insitut für Physik, Johannes Gutenber Universität, Staudingerweg 7, Mainz 55128, Germany
| | - Marialore Sulpizi
- Insitut für Physik, Ruhr Universität Bochum, Universitätstrasse 150, Bochum 44801, Germany
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3
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Prakash K, Sathian SP. Temperature-dependent differential capacitance of an ionic liquid-graphene-based supercapacitor. Phys Chem Chem Phys 2024; 26:4657-4667. [PMID: 38251719 DOI: 10.1039/d3cp05039d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024]
Abstract
One of the critical factors affecting the performance of supercapacitors is thermal management. The design of supercapacitors that operate across a broad temperature range and at high charge/discharge rates necessitates understanding the correlation of the molecular characteristics of the device (such as interfacial structure and inter-ionic and ion-electrode interactions) with its macroscopic properties. In this study, we use molecular dynamics (MD) simulations to investigate the influence of Joule heating on the structure and dynamics of the ionic liquid (IL)/graphite-based supercapacitors. The temperature-dependent electrical double layer (EDL) and differential capacitance-potential (CD-V) curves of two different ([Bmim][BF4] and [Bmim][PF6]) IL-graphene pairs were studied under various thermal gradients. For the [Bmim][BF4] system, the differential capacitance curves transition from 'U' to bell shape under an applied thermal gradient (∇T) in the range from 3.3 K nm-1 to 16.7 K nm-1. Whereas in [Bmim][PF6], we find a positive dependence of differential capacitance with ∇T with a U-shaped CD-V curve. We examine changes in the EDL structure and screening potential (ϕ(z)) as a function of ∇T and correlate them with the trends observed in the CD-V curve. The identified correlation between the interfacial charge density and differential capacitance with thermal gradient would be helpful for the molecular design of the IL-electrode interface in supercapacitors or other chemical engineering applications.
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Affiliation(s)
- Kiran Prakash
- Department of Applied Mechanics and Biomedical Engineering, Indian Institute of Technology Madras, Chennai-600036, Tamil Nadu, India.
| | - Sarith P Sathian
- Department of Applied Mechanics and Biomedical Engineering, Indian Institute of Technology Madras, Chennai-600036, Tamil Nadu, India.
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4
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Wang Y, Tian G. Theoretical Insight into the Imidazolium-Based Ionic Liquid Interface Structure and Differential Capacitance on Au(111): Effects of the Cationic Substituent Group. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:14231-14245. [PMID: 37751408 DOI: 10.1021/acs.langmuir.3c01381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/28/2023]
Abstract
Electric double layers (EDLs) play a key role in the electrochemical and energy storage of supercapacitors. It is important to understand the structure and properties of EDLs. In this work, quantum chemical calculations and molecular dynamics (MD) simulations are used to study the microstructure of EDLs of four different substituents of imidazolium-based bis(trifluoromethylsulfonyl)imide ionic liquids (ILs) on the Au(111) surface. It is shown that the particle interactions influence the different arrangements of the anion and cation. More alkyl substitutions and longer alkyl chains result in a higher ELUMO and thus a stronger interaction energy between cations and electrodes. Strong interactions produce linear patterns of anions/cations on the electrode and a maximum value of differential capacitance near PZC, whereas weak interactions generate worm-like patterns of anions/cations on Au(111) and a minimum value of differential capacitance near the PZC. We hold the opinion that the alkyl substitution has more effects on the EDLs. Our analysis provides a new perspective on EDLs structures at the atomic and molecular level. This study provides a good basis and guidance for further understanding the interface phenomena and characteristics of ionic liquids in electrochemical and energy device applications.
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Affiliation(s)
- Yue Wang
- State Key Laboratory of Complex Non-ferrous Metal Resource Clean Utilization, Kunming University of Science and Technology, Kunming 650093, Yunnan, China
- Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, China
- Yunnan Open University, Kunming 650223, China
| | - Guocai Tian
- State Key Laboratory of Complex Non-ferrous Metal Resource Clean Utilization, Kunming University of Science and Technology, Kunming 650093, Yunnan, China
- Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, China
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5
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High-frequency phenomena and electrochemical impedance spectroscopy at nanoelectrodes. Curr Opin Colloid Interface Sci 2023. [DOI: 10.1016/j.cocis.2022.101654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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6
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He T, Frisbie CD. Sub-Band Filling, Mott-like Transitions, and Ion Size Effects in C 60 Single Crystal Electric Double Layer Transistors. ACS NANO 2022; 16:4823-4830. [PMID: 35243860 DOI: 10.1021/acsnano.2c00222] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Electric double layer transistors (EDLTs) based on C60 single crystals and ionic liquid gates display pronounced peaks in sheet conductance versus gate-induced charge. Sheet conductance is maximized at electron densities near 0.5 e/C60 and is suppressed near 1 e/C60. The conductance suppression depends markedly on the choice of ionic liquid cation, with small cations favoring activated transport and essentially a complete shutdown of conductance at ∼1 e/C60 and larger cations favoring band-like transport, higher overall conductances at all charge densities up to 1.7 e/C60, and weaker suppression at 1 e/C60. Displacement current measurements on C60 EDLTs with small cations show clear evidence of sub-band filling at 1 e/C60, which correlates very well with the minimum in the C60 sheet conductance. Overall, the data suggest a significant Mott-Hubbard-like energy gap opens up in the surface density of states for C60 crystals gated with small cations. The causes of this energy gap may include both electron-electron repulsion and electron-cation attraction at the crystal/ionic liquid interface. The energy gap suppresses the insulator-to-metal transition in C60 EDLTs, but it can be manipulated by choice of electrolyte.
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Affiliation(s)
- Tao He
- State Key Laboratory of Crystal Materials, Shandong University, 250100, Jinan, Shandong, People's Republic of China
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - C Daniel Frisbie
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
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7
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Qing L, Jiang J. Double-Edged Sword of Ion-Size Asymmetry in Energy Storage of Supercapacitors. J Phys Chem Lett 2022; 13:1438-1445. [PMID: 35129327 DOI: 10.1021/acs.jpclett.1c03900] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The advanced supercapacitor is of great significance for renewable energy storage. Achieving its high energy and high power densities remains a huge challenge. Herein, the contribution of ion-size asymmetry to the charging behavior of a supercapacitor is systematically studied using time-dependent density functional theory (TDDFT). We track the time evolution of the ionic microstructure inside the porous electrode and its reservoir and reveal a kinetic charge inversion in the asymmetrical ion-size cases. Compared with the symmetrical ion-size case, we find that the ion-size asymmetry has a double-edged sword effect on the energy storage of a supercapacitor: it accelerates the charging process yet reduces the differential capacitance. Additionally, the energy density and power density can simultaneously increase in the asymmetrical cases, which provides important insights toward the experimental design of supercapacitors with high energy and high power densities.
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Affiliation(s)
- 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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8
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Wang Y, Tian G. The Influence of Anion Structure on the Ionic Liquids/Au (100) Interface by Molecular Dynamics Simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:14059-14071. [PMID: 34797668 DOI: 10.1021/acs.langmuir.1c02129] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The microstructure of electrical double layers (EDLs) of 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4), 1-butyl-3-methylimidazoliumhexafluorophosphate ([Bmim]PF6), and 1-butyl-3-methylimidazoliumbis (trifluoromethylsulfonyl) imide ([Bmim]TFSI) were studied by quantum chemical calculation and molecular dynamics simulation. For the set of ionic liquids investigated here, we found some interesting universal laws due to differences geometry and electronic structure of anions. We show that the morphology of the three anions on the electrode surface is different due to the different geometric structure. The plane formed by the bottom three atoms of the symmetrically tetrahedral BF4- and the bottom atom of the symmetrically octahedral PF6- face the electrode whether the electrode is charged or not, while the conformation of twisted V-shaped TFSI- changes with different surface charges on the electrode. Meanwhile, we also demonstrate that the energy of highest occupied molecular orbital (EHOMO), the energy of lowest unoccupied molecular orbital (ELUMO) and their energies gap (ΔE) are very interesting due to different electronic structure of anions. Specially, the EHOMO, ELUMO, and ΔE were related to the electronegativity of the central atom in the case of the same symmetry on the neutral surface. The more electronegative the central atom is, the lower EHOMO, ELUMO and higher ΔE values are. However, on the charged surface, the interaction between anion and electrode is opposite to ΔE. Moreover, different arrangements of anion and cation are related to the interaction between particles. The stronger interaction leads a double-row structure and the weak interaction lead worm-like and island patterns on Au (100) surface. In general, we observed that the higher ΔE cause stronger interaction, which lead to different patterns on Au (100) surface. Meanwhile, we also confirmed that the stronger interaction between particles and electrode lead to the thinner effective EDL and a large differential capacitance value. These results provide a new perspective for double-layer structure in atomic and molecular level. This is helpful to deepen the understanding of the interface phenomena and characteristics of [Bmim]BF4, [Bmim]PF6, and [Bmim]TFSI on Au (100) system and provide theoretical basis for the application of these kind of systems.
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Affiliation(s)
- Yue Wang
- State Key Laboratory of Complex Non-ferrous Metal Resource Clean Utilization, Kunming University of Science and Technology, Yunnan, Kunming 650093, China
- Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, 650093, China
- Yunnan Open University, Kunming, 650223, China
| | - Guocai Tian
- State Key Laboratory of Complex Non-ferrous Metal Resource Clean Utilization, Kunming University of Science and Technology, Yunnan, Kunming 650093, China
- Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, 650093, China
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9
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Voroshylova IV, Ers H, Koverga V, Docampo-Álvarez B, Pikma P, Ivaništšev VB, Cordeiro M. Ionic liquid–metal interface: The origins of capacitance peaks. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.138148] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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10
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Shin S, Greco F, Maier F, Steinrück HP. Enrichment effects of ionic liquid mixtures at polarized electrode interfaces monitored by potential screening. Phys Chem Chem Phys 2021; 23:10756-10762. [PMID: 33978646 PMCID: PMC8115399 DOI: 10.1039/d0cp04811a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The behavior of ionic liquids (ILs) at charged interfaces is pivotal for their application in supercapacitors and electrochemical cells. Recently, we demonstrated for neat ILs that potential screening at polarized electrode interfaces shows a characteristic voltage dependence, as determined in situ by X-ray photoelectron spectroscopy. Herein, we use this fingerprint-type behavior to characterize the nature of the IL/electrode interfaces for IL mixtures of [C8C1Im][Tf2N] and [C8C1Im]Cl on Au and Pt electrodes. For Au, the IL/electrode interfaces are dominated by the Cl− anions, even down to a 0.1 mol% [C8C1Im]Cl content. In contrast, [Tf2N]− anions enrich at the IL/Pt electrode interfaces down to 10 mol% [C8C1Im][Tf2N]; only at lower concentrations does a transition to Cl− enrichment occur. These mixture studies demonstrate that even small concentrations of another IL or contamination, e.g. remaining from synthesis, can strongly influence the situation at charged IL interfaces. The interface of electrodes and IL mixtures has been studied by in situ XPS. We found that the concentration of counterions at the interface can strongly deviate from the bulk composition due to interactions between electrode and IL.![]()
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Affiliation(s)
- Sunghwan Shin
- Lehrstuhl für Physikalische Chemie 2, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany.
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11
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Electric double layer structure and capacitance of imidazolium-based ionic liquids with FSI− and Tf− anions at graphite electrode by molecular dynamic simulations. J Electroanal Chem (Lausanne) 2019. [DOI: 10.1016/j.jelechem.2019.113452] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Gallegos A, Lian C, Dyatkin B, Wu J. Side-chain effects on the capacitive behaviour of ionic liquids in microporous electrodes. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1650210] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Alejandro Gallegos
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA, USA
| | - Cheng Lian
- State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Shanghai, PR People’s Republic of China
| | - Boris Dyatkin
- A.J. Drexel Nanomaterials Institute and the Department of Materials Science and Engineering, Drexel University, Philadelphia, PA, USA
| | - Jianzhong Wu
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA, USA
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13
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Noh C, Jung Y. Understanding the charging dynamics of an ionic liquid electric double layer capacitor via molecular dynamics simulations. Phys Chem Chem Phys 2019; 21:6790-6800. [PMID: 30735216 DOI: 10.1039/c8cp07200k] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
We investigate the charging phenomena of an electric double layer capacitor (EDLC) by conducting both equilibrium and non-equilibrium molecular dynamics (MD) simulations. A graphene electrode and 1-ethyl-3-methylimidazolium thiocyanate ([EMIM]+[SCN]-) ionic liquid were used as a system for the EDLC. We clarify the ionic layer structure and show that an abrupt change of the ionic layers leads to a high differential capacitance of the EDLC. The charging simulations reveal that the charging dynamics of the EDLC is highly dependent on the rearrangement of the ionic layer structure. Particularly, the electrode charge during the charging process is consistent with the perpendicular displacement of ionic liquid molecules. From this property, we analyze the contribution of each molecular ion to the electrode charge stored during charging. Charging of the EDLC is largely dependent on the desorption of the co-ions from the electrode rather than the adsorption of the counter-ions. In addition, the contribution of bulk ions to the charge stored in the EDLC is as important as that of ions adjacent to the electrode surface contrary to the conventional viewpoint. From these results, we identify the charging mechanism of the EDLC and discuss the relevance to experimental results. Our findings in the present study are expected to play an important role in designing an efficient EDLC with a novel perspective on the charging of the EDLC.
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Affiliation(s)
- Chanwoo Noh
- Department of Chemistry, Seoul National University, Seoul 08826, Korea.
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14
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Jo S, Park SW, Noh C, Jung Y. Computer simulation study of differential capacitance and charging mechanism in graphene supercapacitors: Effects of cyano-group in ionic liquids. Electrochim Acta 2018. [DOI: 10.1016/j.electacta.2018.07.126] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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15
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Ruzanov A, Lembinen M, Jakovits P, Srirama SN, Voroshylova IV, Cordeiro MNDS, Pereira CM, Rossmeisl J, Ivaništšev VB. On the thickness of the double layer in ionic liquids. Phys Chem Chem Phys 2018; 20:10275-10285. [DOI: 10.1039/c7cp07939g] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The Au(111)|BF4−interface model in which BF4−reorients and spontaneously dissociates at surface coverageθ= 1/3.
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Affiliation(s)
- Anton Ruzanov
- Institute of Chemistry, University of Tartu
- 50411 Tartu
- Estonia
| | - Meeri Lembinen
- Institute of Physics, University of Tartu
- 50411 Tartu
- Estonia
| | - Pelle Jakovits
- Mobile & Cloud Computing Laboratory, Institute of Computer Science, University of Tartu
- 50409 Tartu
- Estonia
| | - Satish N. Srirama
- Mobile & Cloud Computing Laboratory, Institute of Computer Science, University of Tartu
- 50409 Tartu
- Estonia
| | - Iuliia V. Voroshylova
- Departamento de Química e Bioquímica, LAQV@REQUIMTE, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre
- Porto
- Portugal
- Departamento de Química e Bioquímica, CIQ(UP), Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre
- Porto
| | - M. Natália D. S. Cordeiro
- Departamento de Química e Bioquímica, LAQV@REQUIMTE, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre
- Porto
- Portugal
| | - Carlos M. Pereira
- Departamento de Química e Bioquímica, CIQ(UP), Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre
- Porto
- Portugal
| | - Jan Rossmeisl
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, København
- Denmark
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16
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Kaur S, Sharma S, Kashyap HK. Bulk and interfacial structures of reline deep eutectic solvent: A molecular dynamics study. J Chem Phys 2017; 147:194507. [DOI: 10.1063/1.4996644] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Supreet Kaur
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Shobha Sharma
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Hemant K. Kashyap
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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17
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Wippermann K, Giffin J, Kuhri S, Lehnert W, Korte C. The influence of water content in a proton-conducting ionic liquid on the double layer properties of the Pt/PIL interface. Phys Chem Chem Phys 2017; 19:24706-24723. [PMID: 28861561 DOI: 10.1039/c7cp04003b] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The influence of the water content of 2-sulfoethylmethylammonium trifluoromethanesulfonate [2-Sema][TfO] on the double layer properties of the interface of platinum and the proton conducting ionic liquid (PIL) is investigated by means of impedance spectroscopy and cyclic voltammetry. By fitting the impedance spectra as complex capacitances, up to four differential double layer capacitances and corresponding time constants are obtained, depending on the potential (U = 0-1.6 V/RHE), water content (0.7-6.1 wt%) and temperature (T = 70-110 °C). Within the whole potential range investigated, a high frequency capacitance, C1, and a low frequency capacitance, C2, can be calculated. In the potential region of hydrogen underpotential deposition (HUPD), C1 can be separated into two parts, C1a and C1b. Whereas the high frequency capacitive processes can mainly be attributed to ion transport processes in the double layer, the low frequency process is ascribed to changes in the interfacial layer, including ad-/desorption and Faradaic processes. Alternative interpretations regarding the reorientation of ions, reconstruction of the metal surface and partial electron transfer between anions and Pt are considered.
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Affiliation(s)
- K Wippermann
- Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research - Fuel Cells (IEK-3), 52425 Jülich, Germany.
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18
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Effects of Alkyl Chain Length on Interfacial Structure and Differential Capacitance in Graphene Supercapacitors: A Molecular Dynamics Simulation Study. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.06.169] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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19
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Begić S, Jónsson E, Chen F, Forsyth M. Molecular dynamics simulations of pyrrolidinium and imidazolium ionic liquids at graphene interfaces. Phys Chem Chem Phys 2017; 19:30010-30020. [DOI: 10.1039/c7cp03389c] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
MD simulations of ionic liquids support AFM data and point towards a likely relationship between interfacial structures and electrochemical performance.
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Affiliation(s)
- Srđan Begić
- ARC Centre of Excellence for Electromaterials Science and Institute for Frontier Materials (IFM)
- Burwood
- Australia
| | - Erlendur Jónsson
- ARC Centre of Excellence for Electromaterials Science and Institute for Frontier Materials (IFM)
- Burwood
- Australia
| | - Fangfang Chen
- ARC Centre of Excellence for Electromaterials Science and Institute for Frontier Materials (IFM)
- Burwood
- Australia
| | - Maria Forsyth
- ARC Centre of Excellence for Electromaterials Science and Institute for Frontier Materials (IFM)
- Burwood
- Australia
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20
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Wu M, Li W, Li S, Feng G. Capacitive performance of amino acid ionic liquid electrolyte-based supercapacitors by molecular dynamics simulation. RSC Adv 2017. [DOI: 10.1039/c7ra00443e] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Capacitance–electric potential curves of amino acid ionic liquid electrolyte-based supercapacitors.
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Affiliation(s)
- Mingbing Wu
- State Key Laboratory of Coal Combustion
- School of Energy and Power Engineering
- Huazhong University of Science and Technology
- China
- Shenzhen Research Institute of Huazhong University of Science and Technology
| | - Wei Li
- State Key Laboratory of Coal Combustion
- School of Energy and Power Engineering
- Huazhong University of Science and Technology
- China
- Shenzhen Research Institute of Huazhong University of Science and Technology
| | - Song Li
- State Key Laboratory of Coal Combustion
- School of Energy and Power Engineering
- Huazhong University of Science and Technology
- China
- Shenzhen Research Institute of Huazhong University of Science and Technology
| | - Guang Feng
- State Key Laboratory of Coal Combustion
- School of Energy and Power Engineering
- Huazhong University of Science and Technology
- China
- Nano Interface Centre for Energy
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21
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Goodwin ZA, Feng G, Kornyshev AA. Mean-Field Theory of Electrical Double Layer In Ionic Liquids with Account of Short-Range Correlations. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2016.12.092] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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22
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Li S, Zhu M, Feng G. The effects of dication symmetry on ionic liquid electrolytes in supercapacitors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:464005. [PMID: 27624416 DOI: 10.1088/0953-8984/28/46/464005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The effects of dication symmetry on the structure and capacitance of the electrical double layers (EDLs) of dicationic ionic liquids (DILs) near graphene electrodes were investigated by molecular dynamics (MD) simulation in this work. Symmetrical 1-hexyl-3-dimethylimidazolium di[bis(trifluoromethyl)imide]([C6(mim)2](Tf2N)2) and asymmetrical 1-(1-trimethylammonium-yl-hexyl)-3-methylimidazolium di[bis(trifluoro-methanesulfonyl)-imide] ([C6(tma)(mim)](Tf2N)2) were both employed. Radial distribution function (RDF) analysis of the two DILs revealed a shorter distance between the cation-anion pairs in symmetrical [C6(mim)2](Tf2N)2), which was attributed to the closely packed imidazolium ring-anion pairs. In contrast, the trimethylammonium head groups and anions exhibit a relatively longer distance, but a stronger correlation in asymmetrical [C6(tma)(mim)](Tf2N)2. In addition, it was illustrated that more symmetrical DIL ions in EDLs are distributed near graphite electrodes and exhibit closer distances to the electrode, which is most probably due to the parallel orientation of imidazolium rings, reducing the distance between the cation and the graphene. In contrast, asymmetrical DILs, with one trimethylammonium head group and one imidazolium ring in the dications, are loosely packed due to their tilting orientation near graphene surfaces. However, the capacitance-potential (C-V) curves of the two DILs are almost the same, regardless of the opposite sign of potential of zero charge (PZC), indicating the insignificant influence of dication symmetry on the capacitance of DIL-based supercapacitors.
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Affiliation(s)
- Song Li
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China. Nano Interface Center for Energy (NICE), School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China
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23
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Minton G, Lue L. The influence of excluded volume and excess ion polarisability on the capacitance of the electric double layer. Mol Phys 2016. [DOI: 10.1080/00268976.2016.1169327] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Geraint Minton
- School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, UK
| | - Leo Lue
- Department of Chemical and Process Engineering, University of Strathclyde, Glasgow, UK
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24
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Affiliation(s)
- Robert Hayes
- Discipline
of Chemistry, The University of Newcastle, NSW 2308, Callaghan, Australia
| | - Gregory G. Warr
- School
of Chemistry, The University of Sydney, NSW 2006, Sydney, Australia
| | - Rob Atkin
- Discipline
of Chemistry, The University of Newcastle, NSW 2308, Callaghan, Australia
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25
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Patel DB, Chauhan KR, Mukhopadhyay I. Unraveling the photoelectrochemical properties of ionic liquids: cognizance of partially reversible redox activity. Phys Chem Chem Phys 2015; 16:22735-44. [PMID: 25234329 DOI: 10.1039/c4cp02683g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Ionic liquid based electrolytes are gaining great interest in the field of photoenergy conversion. We have found that the ionic liquids namely BMIm Cl, BMIm PF6 and BMIm Tf2N inherently offer redox activity. The device performance of the photoelectrochemical (PEC) cells of the configuration PbOx (0.25 cm(2))|blank ionic liquids|platinum (2 cm(2)) was analyzed in detail to get insights into the working principle of such systems. It was found that partially reversible redox ion pairs diminish the performance of such cells as power generating devices. The partial redox activity of the ionic liquids was confirmed by a number of observations derived from the PEC spectra. The important parameter, Vredox, which determines the performance of any PEC cell was also calculated for all the ionic liquids. The difficulties that arise in high frequency C-V measurements for ionic liquid systems were overcome by choosing the appropriate probing frequency. The evaluated Vredox of BMIm Cl, BMIm PF6 and BMIm Tf2N ionic liquids was found to be -0.30, -0.20 and -0.78 V (vs. NHE), respectively. This study will be beneficial to understand the role of ionic liquids as redox active electrolyte media in several applications.
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Affiliation(s)
- Dipal B Patel
- School of Solar Energy, Pandit Deendayal Petroleum University, Raisan, Gandhinagar-382007, India.
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26
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Xiao C, Rehman A, Zeng X. Evaluation of the dynamic electrochemical stability of ionic liquid–metal interfaces against reactive oxygen species using an in situ electrochemical quartz crystal microbalance. RSC Adv 2015. [DOI: 10.1039/c5ra00396b] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The dynamic interactions between the electrochemically generated superoxide radical (O2˙−) and three structurally different ionic liquids (ILs) were characterized using an electrochemical quartz crystal microbalance.
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Affiliation(s)
- Chunhui Xiao
- Department of Chemistry
- Oakland University
- Rochester
- USA
| | - Abdul Rehman
- Department of Chemistry
- Oakland University
- Rochester
- USA
| | - Xiangqun Zeng
- Department of Chemistry
- Oakland University
- Rochester
- USA
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27
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Zhao Y, Lawrie JL, Beavers KR, Laibinis PE, Weiss SM. Effect of DNA-induced corrosion on passivated porous silicon biosensors. ACS APPLIED MATERIALS & INTERFACES 2014; 6:13510-13519. [PMID: 25089918 DOI: 10.1021/am502582s] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This work examines the influence of charge density and surface passivation on the DNA-induced corrosion of porous silicon (PSi) waveguides in order to improve PSi biosensor sensitivity, reliability, and reproducibility when exposed to negatively charged DNA molecules. Increasing the concentration of either DNA probes or targets enhances the corrosion process and masks binding events. While passivation of the PSi surface by oxidation and silanization is shown to diminish the corrosion rate and lead to a saturation in the changes by corrosion after about 2 h, complete mitigation can be achieved by replacing the DNA probe molecules with charge-neutral PNA probe molecules. A model to explain the DNA-induced corrosion behavior, consistent with experimental characterization of the PSi through Fourier transform infrared spectroscopy and prism coupling optical measurements, is also introduced.
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Affiliation(s)
- Yiliang Zhao
- Interdisciplinary Graduate Program in Materials Science, ‡Department of Chemical and Biomolecular Engineering, and §Department of Electrical Engineering and Computer Science, Vanderbilt University , Nashville, Tennessee 37235, United States
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28
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Sha M, Dou Q, Luo F, Zhu G, Wu G. Molecular insights into the electric double layers of ionic liquids on Au(100) electrodes. ACS APPLIED MATERIALS & INTERFACES 2014; 6:12556-12565. [PMID: 25046476 DOI: 10.1021/am502413m] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The electric double layer structure and differential capacitance of single crystalline Au(100) electrodes in the ionic liquid 1-butyl-3-methyl-imidazolium hexafluorophosphate are investigated using molecular dynamics simulations. Results show strong adsorption on the electrode surface. The potential of zero charge (pzc) and maxima of differential capacitance are strongly dependent on the adsorption layer structure. At potentials near the pzc, cations and anions adjacent to the electrode surface are coadsorbed on the same screening layer. This strong adsorption layer results in overscreening effects on the compact layer and induces both a bell-shaped differential capacitance curve and a positive pzc. Moreover, the potential required for transition from overscreening to overcrowding is about 4.0 V. This transition potential may be attributed to the higher interaction energy between the Au(100) electrode and ions compared with the binding energy in our cation-anion system.
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Affiliation(s)
- Maolin Sha
- Department of Chemistry and Chemical Engineering, Hefei Normal University , Hefei 230061, China
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29
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Han Y, Huang S, Yan T. A mean-field theory on the differential capacitance of asymmetric ionic liquid electrolytes. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:284103. [PMID: 24920102 DOI: 10.1088/0953-8984/26/28/284103] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The size of ions significantly influences the electric double layer structure of room temperature ionic liquid (IL) electrolytes and their differential capacitance (Cd). In this study, we extended the mean-field theory (MFT) developed independently by Kornyshev (2007J. Phys. Chem. B 111 5545-57) and Kilic, Bazant, and Ajdari (2007 Phys. Rev. E 75 021502) (the KKBA MFT) to take into account the asymmetric 1:1 IL electrolytes by introducing an additional parameter ξ for the anion/cation volume ratio, besides the ionic compressibility γ in the KKBA MFT. The MFT of asymmetric ions becomes KKBA MFT upon ξ = 1, and further reduces to Gouy-Chapman theory in the γ → 0 limit. The result of the extended MFT demonstrates that the asymmetric ILs give rise to an asymmetric Cd, with the higher peak in Cd occurring at positive polarization for the smaller anionic size. At high potential, Cd decays asymptotically toward KKBA MFT characterized by γ for the negative polarization, and characterized by ξγ for the positive polarization, with inverse-square-root behavior. At low potential, around the potential of zero charge, the asymmetric ions cause a higher Cd, which exceeds that of Gouy-Chapman theory.
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Affiliation(s)
- Yining Han
- Tianjin Key Laboratory of Metal- and Molecule-Based Material Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Institute of New Energy Material Chemistry, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
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30
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Borisenko N, Atkin R, Lahiri A, El Abedin SZ, Endres F. Effect of dissolved LiCl on the ionic liquid-Au(111) interface: an in situ STM study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:284111. [PMID: 24919647 DOI: 10.1088/0953-8984/26/28/284111] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The structure of the electrolyte/electrode interface plays a significant role in electrochemical processes. To date, most studies are focusing on understanding the interfacial structure in pure ionic liquids. In this paper in situ scanning tunnelling microscopy (STM) has been employed to elucidate the structure of the charged Au(111)-ionic liquid (1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate, [Py1,4]FAP) interface in the presence of 0.1 M LiCl. The addition of the Li salt to the ionic liquid has a strong influence on the interfacial structure. In the first STM scan in situ measurements reveal that Au(111) undergoes the (22 x √3) 'herringbone' reconstruction in a certain potential regime, and there is strong evidence that the gold surface dissolves at negative electrode potentials in [Py1,4]FAP containing LiCl. Bulk deposition of Li is obtained at -2.9 V in the second STM scan.
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Affiliation(s)
- Natalia Borisenko
- Institute of Electrochemistry, Clausthal University of Technology, Arnold-Sommerfeld-Straße 6, D-38678 Clausthal-Zellerfeld, Germany
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31
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Breitsprecher K, Košovan P, Holm C. Coarse-grained simulations of an ionic liquid-based capacitor: II. Asymmetry in ion shape and charge localization. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:284114. [PMID: 24919958 DOI: 10.1088/0953-8984/26/28/284114] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In this work, which is a continuation of part I, we introduce a primitive model for an ionic liquid (IL) that can account for the planar shape of cations typical for ILs like imidazolium. The model consists of a spherical anion and a triangular cation consisting of three spheres, where one or all three vertices of the triangle can carry electric charge. We use molecular dynamics simulations to study the differential capacitance Cd of an ionic liquid confined between two planar electrodes. Our goal is to elucidate the complex dependence of Cd on the electrode potential U in terms of simple entities such as the shape and charge distribution of the ions. For this purpose, we compare the results from the current model to the results based on the models with spherical cations that possess asymmetry in ion valence and shape that were analyzed in detail in part I of this work. We show that the various possible stackings of the triangles near the cathode lead to noticeable new features in Cd(U) as compared to the spherical models. Different distributions of charges on the triangle lead to different preferred orientations of the cations near the cathode that are moreover potential dependent.
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32
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Breitsprecher K, Košovan P, Holm C. Coarse-grained simulations of an ionic liquid-based capacitor: I. Density, ion size, and valency effects. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:284108. [PMID: 24919407 DOI: 10.1088/0953-8984/26/28/284108] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We introduce a hierarchy of generic coarse-grained models of ionic liquids of increasing complexity. We use them in molecular dynamics simulations to study the differential capacitance of a capacitor consisting of an ionic liquid between two planar electrodes. The primary goal is to explain the complex dependence of the differential capacitance Cd on the electrode potential U in simple terms, e.g. in terms of the size and valency of the ions. For this purpose we introduce the symmetric model A, which qualitatively reproduces the Cd(U) dependence predicted by the mean-field theory but also reveals strong quantitative deviations. We further introduce size asymmetry in model A by increasing the cation size. In model B we vary the cation valency, keeping the sizes of both ions constant. We show that simultaneous increases in size and valency may compensate for each other, leading to a Cd(U) very similar to that for the symmetric case. We interpret distinct features in Cd(U) on the basis of the density profiles of the ions and charge density profiles. We focus on the first two ion layers at the electrode, and demonstrate that the polarization of the ionic liquid proceeds through replacement of one ion type by the other, in contrast to the simple increase in ion concentrations typical for dilute systems. The understanding gained for the simple models serves as a reference for interpretation of complex effects of ion size, valency and shape. This is carried through in part II (a separate article) where we show how the planar shape of ions in model C brings new features to the Cd(U) curve and also to the polarization mechanism.
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Affiliation(s)
- Konrad Breitsprecher
- Institute for Computational Physics, University of Stuttgart, Stuttgart, Germany
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33
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Li S, Feng G, Cummings PT. Interfaces of dicationic ionic liquids and graphene: a molecular dynamics simulation study. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:284106. [PMID: 24920318 DOI: 10.1088/0953-8984/26/28/284106] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Molecular dynamics simulations were performed to investigate the interfacial structure and capacitance of electrical double layers (EDLs) in dicationic ionic liquids (DILs) 1-alkyl-3-dimethylimidazolium tetrafluoroborate [Cn(mim)2](BF4)2 (n = 3, 6, 9), with respect to a baseline of a monocationic ionic liquid [C3mim][BF4], near planar carbon electrodes consisting of graphene sheets. The simulation results show that an adsorbed layer with double peaks is exclusively found for [C3(mim)2](BF4)2, while a single peak of the other three cations is observed at the neutral electrode, due to the difference in ion-wall interaction and cation-anion association. As the electrode becomes negatively charged, the second peak of [C3(mim)2](2+) is dramatically reduced, whereas those of [C6(mim)2](2+) and [C9(mim)2](2+) become non-trivial. The capacitance-potential curve of EDLs in DILs manifests a transition from camel shape to bell shape as the cation chain length increases, which is attributed to the enlargement of ion adsorption (per unit charge) on the electrode and the decrease of attractive interaction between ions.
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Affiliation(s)
- Song Li
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235, USA
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34
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Turesson M, Szparaga R, Ma K, Woodward CE, Forsman J. Classical density functional theory & simulations on a coarse-grained model of aromatic ionic liquids. SOFT MATTER 2014; 10:3229-3237. [PMID: 24718295 DOI: 10.1039/c3sm53169d] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A new classical density functional approach is developed to accurately treat a coarse-grained model of room temperature aromatic ionic liquids. Our major innovation is the introduction of charge-charge correlations, which are treated in a simple phenomenological way. We test this theory on a generic coarse-grained model for aromatic RTILs with oligomeric forms for both cations and anions, approximating 1-alkyl-3-methyl imidazoliums and BF₄⁻, respectively. We find that predictions by the new density functional theory for fluid structures at charged surfaces are very accurate, as compared with molecular dynamics simulations, across a range of surface charge densities and lengths of the alkyl chain. Predictions of interactions between charged surfaces are also presented.
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Affiliation(s)
- Martin Turesson
- Theoretical Chemistry, Lund University, P.O.Box 124, S-221 00, Lund, Sweden.
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35
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36
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Affiliation(s)
- Maxim V Fedorov
- Department of Physics, Scottish University Physics Alliance (SUPA), University of Strathclyde , John Anderson Bldg, 107 Rottenrow, Glasgow, G4 0NG United Kingdom
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37
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Costa R, Pereira CM, Silva AF. Dicationic Ionic Liquid: Insight in the Electrical Double Layer Structure at mercury, glassy carbon and gold surfaces. Electrochim Acta 2014. [DOI: 10.1016/j.electacta.2013.11.034] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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38
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Comparing the differential capacitance of two ionic liquid electrolytes: Effects of specific adsorption. Electrochem commun 2014. [DOI: 10.1016/j.elecom.2013.10.027] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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39
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Burt R, Birkett G, Zhao XS. A review of molecular modelling of electric double layer capacitors. Phys Chem Chem Phys 2014; 16:6519-38. [DOI: 10.1039/c3cp55186e] [Citation(s) in RCA: 180] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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40
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Influence of the electrode potential and in situ STM scanning conditions on the phase boundary structure of the single crystal Bi(111)|1-butyl-4-methylpyridinium tetrafluoroborate interface. J Electroanal Chem (Lausanne) 2013. [DOI: 10.1016/j.jelechem.2013.10.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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41
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Bhuiyan LB, Lamperski S. On the interfacial capacitance of an electrolyte at a metallic electrode around zero surface charge. Mol Phys 2012. [DOI: 10.1080/00268976.2012.745954] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Lutful Bari Bhuiyan
- a Laboratory of Theoretical Physics, Department of Physics , University of Puerto Rico , San Juan , Puerto Rico 00931-3343
| | - Stanisław Lamperski
- b Department of Physical Chemistry, Faculty of Chemistry , Adam Mickiewicz University in Poznań , Umultowska 89b, 61-614 Poznań
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42
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Su YZ, Yan JW, Li MG, Xie ZX, Mao BW, Tian ZQ. Adsorption of Solvent Cations on Au(111) and Au(100) in Alkylimidazolium-Based Ionic Liquids – Worm-Like versus Micelle-Like Structures. ACTA ACUST UNITED AC 2012. [DOI: 10.1524/zpch.2012.0255] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
By employing high resolution in-situ STM, the adsorption of alkylimidazolium-based cations of EMI
+
, PMI
+
, BMI
+
and OMI
+
on Au(111) and Au(100) surfaces are investigated systematically. The cation adsorption on both Au(111) and Au(100) are composed of double rows arising from counter-facing imidazolium-based cation pairs. On Au(100), the double rows associated with the four cations show micelle-like appearance along the two √ 2 directions of the Au(100) surface lattice units. The width of the double rows varies depending on the side chain length of the cations, but is constrained by the periodicity along the √ 2 directions. Anions of BF
4
-
, PF
6
-
, CF3SO
3
-
and Tf2N
-
do not influence the micelle-like adsorption structure. On Au(111), the double rows are formed only when the terraces are etched to several atoms wide. Most likely, the underneath Au surface experiences restructuring to accommodate the double row structure, and the worm-like orientation of the double rows is the consequence of strain release. Both the micelle-like and worm-like adsorption structures would be lifted upon cathodic potential excursions when the surfaces are driven to undergo ordinary Au(100)-hex and Au(111)-(√ 3 × 22) reconstructions. These results reveal that the ordered micelle-like structure on Au(100) and the irregular worm-like structure on Au(111) are of the same nature.
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Affiliation(s)
| | | | | | | | | | - Zhong-Qun Tian
- Xiamen University, State Key Lab of Physical, Xiamen, 361005, Volksrepublik China
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43
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Roling B, Drüschler M, Huber B. Slow and fast capacitive process taking place at the ionic liquid/electrode interface. Faraday Discuss 2012; 154:303-11; discussion 313-33, 465-71. [PMID: 22455027 DOI: 10.1039/c1fd00088h] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electrochemical impedance spectroscopy was used to characterise the interface between the ultrapure room temperature ionic liquid 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate and a Au(111) working electrode at electrode potentials more positive than the open circuit potential (-0.14 V vs. Pt pseudo-reference). Plots of the potential-dependent data in the complex capacitance plane reveal the existence of a fast and a slow capacitive process. In order to derive the contribution of both processes to the overall capacitance, the complex capacitance data were fitted using an empirical Cole-Cole equation. The differential capacitance of the fast process is almost constant between -0.14 V and +0.2 V (vs. Pt pseudo-reference) and decreases at more positive potentials, while the differential capacitance of the slower process exhibits a maximum at +0.2 V. This maximum leads to a maximum in the overall differential capacitance. We attribute the slow process to charge redistributions in the innermost ion layer, which require an activation energy in excess of that for ion transport in the room temperature ionic liquid. The differential capacitance maximum of the slow process at +0.2 V is most likely caused by reorientations of the 1-butyl-1l-methylpyrrolidinium cations in the innermost layer with the positively charged ring moving away from the Au(111) surface and leaving behind voids which are then occupied by anions. In a recent Monte Carlo simulation by Federov, Georgi and Kornyshev (Electrochem. Commun. 2010, 12, 296), such a process was identified as the origin of a differential capacitance maximum in the anodic regime. Our results suggest that the time scales of capacitive processes at the ionic liquid/metal interface are an important piece of information and should be considered in more detail in future experimental and theoretical studies.
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Affiliation(s)
- Bernhard Roling
- Department of Chemistry, Philipps- University of Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany.
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44
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Si X, Li S, Wang Y, Ye S, Yan T. Effects of Specific Adsorption on the Differential Capacitance of Imidazolium-Based Ionic Liquid Electrolytes. Chemphyschem 2012; 13:1671-6. [DOI: 10.1002/cphc.201200013] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Indexed: 11/12/2022]
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45
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Drüschler M, Borisenko N, Wallauer J, Winter C, Huber B, Endres F, Roling B. New insights into the interface between a single-crystalline metal electrode and an extremely pure ionic liquid: slow interfacial processes and the influence of temperature on interfacial dynamics. Phys Chem Chem Phys 2012; 14:5090-9. [PMID: 22402629 DOI: 10.1039/c2cp40288b] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Ionic liquids are of high interest for the development of safe electrolytes in modern electrochemical cells, such as batteries, supercapacitors and dye-sensitised solar cells. However, electrochemical applications of ionic liquids are still hindered by the limited understanding of the interface between electrode materials and ionic liquids. In this article, we first review the state of the art in both experiment and theory. Then we illustrate some general trends by taking the interface between the extremely pure ionic liquid 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate and an Au(111) electrode as an example. For the study of this interface, electrochemical impedance spectroscopy was combined with in situ STM and in situ AFM techniques. In addition, we present new results for the temperature dependence of the interfacial capacitance and dynamics. Since the interfacial dynamics are characterised by different processes taking place on different time scales, the temperature dependence of the dynamics can only be reliably studied by recording and carefully analysing broadband capacitance spectra. Single-frequency experiments may lead to artefacts in the temperature dependence of the interfacial capacitance. We demonstrate that the fast capacitive process exhibits a Vogel-Fulcher-Tamman temperature dependence, since its time scale is governed by the ionic conductivity of the ionic liquid. In contrast, the slower capacitive process appears to be Arrhenius activated. This suggests that the time scale of this process is determined by a temperature-independent barrier, which may be related to structural reorganisations of the Au surface and/or to charge redistributions in the strongly bound innermost ion layer.
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Affiliation(s)
- Marcel Drüschler
- Department of Chemistry, Philipps-University of Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
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Siinor L, Siimenson C, Ivaništšev V, Lust K, Lust E. Influence of cation chemical composition and structure on the double layer capacitance for Bi(111)|room temperature ionic liquid interface. J Electroanal Chem (Lausanne) 2012. [DOI: 10.1016/j.jelechem.2012.01.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Shim Y, Kim HJ, Jung Y. Graphene-based supercapacitors in the parallel-plate electrode configuration: Ionic liquidsversus organic electrolytes. Faraday Discuss 2012; 154:249-63; discussion 313-33, 465-71. [DOI: 10.1039/c1fd00086a] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Mei X, Ouyang J. Electronically and ionically conductive gels of ionic liquids and charge-transfer tetrathiafulvalene-tetracyanoquinodimethane. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:10953-10961. [PMID: 21800893 DOI: 10.1021/la202465k] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Electronically and ionically conductive gels were fabricated by mixing and mechanically grinding neutral tetrathiafulvalene (TTF) and tetracyanoquinodimethane (TCNQ) in ionic liquids (ILs) like 3-ethyl-1-methylimidazolium dicyanoamide (EMIDCA), 1-ethyl-3-methylimidazolium thiocyanate (EMISCN), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITf(2)N), trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide (P(14,6,6,6)Tf(2)N), and methyl-trioctylammonium bis(trifluoromethylsulfonyl)imide (MOATf(2)N). Charge-transfer TTF-TCNQ crystallites were generated during the mechanical grinding as indicated by the UV-visibile-near-infrared (UV-vis-NIR) absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction. The charge-transfer TTF-TCNQ crystallites have a needle-like shape. They form solid networks to gelate the ILs. The gel behavior is confirmed by the dynamic mechanical measurements. It depends on both the anions and cations of the ILs. In addition, when 1-methyl-3-butylimidazolium tetrafluoroborate (BMIBF(4)) and 1-methyl-3-propylimidazolium iodide (PMII) were used, the TTF-TCNQ/IL mixtures did not behave as gels. The TTF-TCNQ/IL gels are both electronically and ionically conductive, because the solid phase formed by the charge-transfer TTF-TCNQ crystallites is electronically conductive, while the ILs are ionically conductive. The gel formation is related to needle-like charge-transfer TTF-TCNQ cyrstallites and the π-π and Coulombic interactions between TTF-TCNQ and ILs.
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Affiliation(s)
- Xiaoguang Mei
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117576
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Forsman J, Woodward CE, Trulsson M. A Classical Density Functional Theory of Ionic Liquids. J Phys Chem B 2011; 115:4606-12. [DOI: 10.1021/jp111747w] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Jan Forsman
- Theoretical Chemistry, Chemical Centre, P.O. Box 124, S-221 00 Lund, Sweden
| | - Clifford E. Woodward
- School of Physical, Environmental and Physical Sciences, University College, University of New South Wales, ADFA Canberra ACT 2600, Australia
| | - Martin Trulsson
- Theoretical Chemistry, Chemical Centre, P.O. Box 124, S-221 00 Lund, Sweden
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Ganapatibhotla LVNR, Wu L, Zheng J, Jia X, Roy D, McLaughlin JB, Krishnan S. Ionic liquids with fluorinated block-oligomer tails: Influence of self-assembly on transport properties. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c1jm14526f] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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