51
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Brkljača Z, Klimczak M, Miličević Z, Weisser M, Taccardi N, Wasserscheid P, Smith DM, Magerl A, Smith AS. Complementary Molecular Dynamics and X-ray Reflectivity Study of an Imidazolium-Based Ionic Liquid at a Neutral Sapphire Interface. J Phys Chem Lett 2015; 6:549-55. [PMID: 26261977 DOI: 10.1021/jz5024493] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Understanding the molecular-level behavior of ionic liquids (ILs) at IL-solid interfaces is of fundamental importance with respect to their application in, for example, electrochemical systems and electronic devices. Using a model system, consisting of an imidazolium-based IL ([C2Mim][NTf2]) in contact with a sapphire substrate, we have approached this problem using a complementary combination of high-resolution X-ray reflectivity measurements and atomistic molecular dynamics (MD) simulations. Our strategy enabled us to compare experimental and theoretically calculated reflectivities in a direct manner, thereby critically assessing the applicability of several force-field variants. On the other hand, using the best-matching MD description, we are able to describe the nature of the model IL-solid interface in appreciable detail. More specifically, we find that characteristic interactions between the surface hydroxyl groups and donor and acceptor sites on the IL constituents have a dominant role in inducing a multidimensional layering profile of the cations and anions.
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Affiliation(s)
- Zlatko Brkljača
- †Institute for Theoretical Physics, FAU Erlangen-Nürnberg, Staudtstrasse 7, 91058 Erlangen, Germany
| | - Michael Klimczak
- ‡Crystallography and Structural Physics, FAU Erlangen-Nürnberg, Staudtstrasse 3, 91058 Erlangen, Germany
| | - Zoran Miličević
- †Institute for Theoretical Physics, FAU Erlangen-Nürnberg, Staudtstrasse 7, 91058 Erlangen, Germany
| | - Matthias Weisser
- ‡Crystallography and Structural Physics, FAU Erlangen-Nürnberg, Staudtstrasse 3, 91058 Erlangen, Germany
| | - Nicola Taccardi
- §Chemical Reaction Engineering, FAU Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
| | - Peter Wasserscheid
- §Chemical Reaction Engineering, FAU Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
| | - David M Smith
- ⊥Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
- ∥Center for Computational Chemistry, FAU Erlangen-Nürnberg, Nägelsbachstrasse 25, 91052 Erlangen, Germany
| | - Andreas Magerl
- ‡Crystallography and Structural Physics, FAU Erlangen-Nürnberg, Staudtstrasse 3, 91058 Erlangen, Germany
| | - Ana-Sunčana Smith
- †Institute for Theoretical Physics, FAU Erlangen-Nürnberg, Staudtstrasse 7, 91058 Erlangen, Germany
- ⊥Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia
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52
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Elbourne A, Voïtchovsky K, Warr GG, Atkin R. Ion structure controls ionic liquid near-surface and interfacial nanostructure. Chem Sci 2015; 6:527-536. [PMID: 28936307 PMCID: PMC5588538 DOI: 10.1039/c4sc02727b] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 10/29/2014] [Indexed: 01/22/2023] Open
Abstract
A unique, but unifying, feature of ionic liquids (ILs) is that they are nanostructured on the length scale of the ions; in many ILs well-defined polar and apolar domains exist and may percolate through the liquid. Near a surface the isotropic symmetry of the bulk structure is broken, resulting in different nanostructures which, until now, have only been studied indirectly. In this paper, in situ amplitude modulated atomic force microscopy (AM-AFM) has been used to resolve the 3-dimensional nanostructure of five protic ILs at and near the surface of mica. The surface and near surface structures are distinct and remarkably well-defined, but are very different from previously accepted descriptions. Interfacial nanostructure is strongly influenced by the registry between cations and the mica surface charge sites, whereas near surface nanostructure is sensitive to both cation and anion structure. Together these ILs reveal how interfacial nanostructure can be tuned through ion structure, informing "bottom-up" design and optimisation of ILs for diverse technologies including heterogeneous catalysis, lubrication, electrochemical processes, and nanofluids.
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Affiliation(s)
- Aaron Elbourne
- Discipline of Chemistry , University of Newcastle , NSW 2308 , Callaghan , Australia .
| | | | - Gregory G Warr
- School of Chemistry , University of Sydney , NSW 2006 , Australia
| | - Rob Atkin
- Discipline of Chemistry , University of Newcastle , NSW 2308 , Callaghan , Australia .
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53
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McLean B, Li H, Stefanovic R, Wood RJ, Webber GB, Ueno K, Watanabe M, Warr GG, Page A, Atkin R. Nanostructure of [Li(G4)] TFSI and [Li(G4)] NO3solvate ionic liquids at HOPG and Au(111) electrode interfaces as a function of potential. Phys Chem Chem Phys 2015; 17:325-33. [DOI: 10.1039/c4cp04522j] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Atomic force microscopy (AFM) force measurements have been used to study the solvate ionic liquid (IL) double layer nanostructure at highly ordered pyrolytic graphite (HOPG) and Au(111) electrode surfaces as a function of potential.
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Affiliation(s)
- Ben McLean
- Discipline of Chemistry
- The University of Newcastle
- Callaghan
- Australia
| | - Hua Li
- Discipline of Chemistry
- The University of Newcastle
- Callaghan
- Australia
| | - Ryan Stefanovic
- Discipline of Chemistry
- The University of Newcastle
- Callaghan
- Australia
| | - Ross J. Wood
- Discipline of Chemistry
- The University of Newcastle
- Callaghan
- Australia
| | - Grant B. Webber
- Discipline of Chemistry
- The University of Newcastle
- Callaghan
- Australia
| | - Kazuhide Ueno
- Department of Chemistry and Biotechnology
- Yokohama National University
- Hodogaya-ku
- Japan
| | - Masayoshi Watanabe
- Department of Chemistry and Biotechnology
- Yokohama National University
- Hodogaya-ku
- Japan
| | | | - Alister Page
- Discipline of Chemistry
- The University of Newcastle
- Callaghan
- Australia
| | - Rob Atkin
- Discipline of Chemistry
- The University of Newcastle
- Callaghan
- Australia
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54
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Heinze MT, Zill JC, Matysik J, Einicke WD, Gläser R, Stark A. Solid-ionic liquid interfaces: pore filling revisited. Phys Chem Chem Phys 2014; 16:24359-72. [PMID: 25300707 DOI: 10.1039/c4cp02749c] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The properties of ionic liquids on ordered and non-ordered mesoporous silicas (silica gel, MCM-41, SBA-15) were studied by nitrogen sorption, mercury intrusion and thermogravimetric analyses, as well as (129)Xe-NMR spectroscopy. The ionic liquids investigated are based on the 1-hexyl-3-methylimidazolium cation, which was combined with anions of low (bis(trifluoromethanesulfonyl)imide; [NTf2](-)), medium (trifluoromethylsulfonate; [CF3SO3](-)) to high (acetate; [OAc](-)) basicity. The surface coverage depends on both the type of ionic liquid and support used. This results not only in layer or droplet formation, but also in different physico-chemical properties of the ionic liquid when compared to the bulk, depending mainly on the strength of interaction at the interface. Furthermore, the mercury intrusion analysis of mesopores is shown not to be suitable for supported ionic liquids.
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Affiliation(s)
- M T Heinze
- Institute of Chemical Technology, Universität Leipzig, Linnéstrasse 3, D-04103 Leipzig, Germany
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55
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Smith AM, Parkes MA, Perkin S. Molecular Friction Mechanisms Across Nanofilms of a Bilayer-Forming Ionic Liquid. J Phys Chem Lett 2014; 5:4032-4037. [PMID: 26276489 DOI: 10.1021/jz502188g] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The prevailing paradigm in boundary lubrication asserts, in essence, that surfaces coated in amphiphiles slide past each other by way of the "slippery" exposed alkyl chains while the polar head group remains anchored at the surface. Here we show, for ionic liquid boundary lubricants, that the molecular mechanism of shearing is more subtle; while a monolayer on each surface gives rise to alkyl plane shearing, a bilayer on each surface shears at the ionic (nonalkyl) interface. The incorporation of water from the environment dramatically alters the shear at ionic interfaces but leaves alkyl plane shearing unaffected. Our experiments involve shearing two identical and atomically smooth surfaces past one another with films of an ionic liquid between, with subnanometer control of the film thickness and ultrasensitive shear stress resolution. With this, we uncover molecular mechanistic details relevant to boundary lubrication in general and the development of ionic liquid lubricants in particular.
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Affiliation(s)
- Alexander M Smith
- †Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Michael A Parkes
- ‡Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Susan Perkin
- †Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
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56
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Zhong YX, Yan JW, Li MG, Zhang X, He DW, Mao BW. Resolving Fine Structures of the Electric Double Layer of Electrochemical Interfaces in Ionic Liquids with an AFM Tip Modification Strategy. J Am Chem Soc 2014; 136:14682-5. [DOI: 10.1021/ja508222m] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Yun-Xin Zhong
- State
Key Laboratory of Physical
Chemistry of Solid Surfaces and Department of Chemistry, College of
Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Jia-Wei Yan
- State
Key Laboratory of Physical
Chemistry of Solid Surfaces and Department of Chemistry, College of
Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Mian-Gang Li
- State
Key Laboratory of Physical
Chemistry of Solid Surfaces and Department of Chemistry, College of
Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Xiao Zhang
- State
Key Laboratory of Physical
Chemistry of Solid Surfaces and Department of Chemistry, College of
Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Ding-Wen He
- State
Key Laboratory of Physical
Chemistry of Solid Surfaces and Department of Chemistry, College of
Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Bing-Wei Mao
- State
Key Laboratory of Physical
Chemistry of Solid Surfaces and Department of Chemistry, College of
Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
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57
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Lee AA, Vella D, Perkin S, Goriely A. Unravelling nanoconfined films of ionic liquids. J Chem Phys 2014; 141:094904. [DOI: 10.1063/1.4893714] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Alpha A. Lee
- Mathematical Institute, Andrew Wiles Building, University of Oxford, Woodstock Road, Oxford OX2 6GG, United Kingdom
| | - Dominic Vella
- Mathematical Institute, Andrew Wiles Building, University of Oxford, Woodstock Road, Oxford OX2 6GG, United Kingdom
| | - Susan Perkin
- Department of Chemistry, University of Oxford, Oxford OX1 3QZ, United Kingdom
| | - Alain Goriely
- Mathematical Institute, Andrew Wiles Building, University of Oxford, Woodstock Road, Oxford OX2 6GG, United Kingdom
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58
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Addicoat MA, Stefanovic R, Webber GB, Atkin R, Page AJ. Assessment of the Density Functional Tight Binding Method for Protic Ionic Liquids. J Chem Theory Comput 2014; 10:4633-4643. [PMID: 25328497 PMCID: PMC4196743 DOI: 10.1021/ct500394t] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Indexed: 01/17/2023]
Abstract
![]()
Density
functional tight binding (DFTB), which is ∼100–1000
times faster than full density functional theory (DFT), has been used
to simulate the structure and properties of protic ionic liquid (IL)
ions, clusters of ions and the bulk liquid. Proton affinities for
a wide range of IL cations and anions determined using DFTB generally
reproduce G3B3 values to within 5–10 kcal/mol. The structures
and thermodynamic stabilities of n-alkyl ammonium
nitrate clusters (up to 450 quantum chemical atoms) predicted with
DFTB are in excellent agreement with those determined using DFT. The
IL bulk structure simulated using DFTB with periodic boundary conditions
is in excellent agreement with published neutron diffraction data.
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Affiliation(s)
- Matthew A Addicoat
- School of Engineering and Science, Jacobs University Bremen , Campus Ring 1, 28759 Bremen, Germany
| | - Ryan Stefanovic
- Newcastle Institute for Energy and Resources, The University of Newcastle , NSW 2308, Callaghan, Australia
| | - Grant B Webber
- Newcastle Institute for Energy and Resources, The University of Newcastle , NSW 2308, Callaghan, Australia
| | - Rob Atkin
- Newcastle Institute for Energy and Resources, The University of Newcastle , NSW 2308, Callaghan, Australia
| | - Alister J Page
- Newcastle Institute for Energy and Resources, The University of Newcastle , NSW 2308, Callaghan, Australia
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59
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Li H, Wood RJ, Endres F, Atkin R. Influence of alkyl chain length and anion species on ionic liquid structure at the graphite interface as a function of applied potential. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:284115. [PMID: 24920055 DOI: 10.1088/0953-8984/26/28/284115] [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
Atomic force microscopy (AFM) force measurements elucidate the effect of cation alkyl chain length and the anion species on ionic liquid (IL) interfacial structure at highly ordered pyrolytic graphite (HOPG) surfaces as a function of potential. Three ILs are examined: 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIM] FAP), 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([EMIM] FAP), and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM] TFSA). The step-wise force-distance profiles indicate the ILs adopt a multilayered morphology near the surface. When the surface is biased positively or negatively versus Pt quasireference electrode, both the number of steps, and the force required to rupture each step increase, indicating stronger interfacial structure. At all potentials, push-through forces for [HMIM] FAP are the highest, because the long alkyl chain results in strong cohesive interactions between cations, leading to well-formed layers that resist the AFM tip. The most layers are observed for [EMIM] FAP, because the C2 chains are relatively rigid and the dimensions of the cation and anion are similar, facilitating neat packing. [EMIM] TFSA has the smallest push-through forces and fewest layers, and thus the weakest interfacial structure. Surface-tip attractive forces are measured for all ILs. At the same potential, the attractions are the strongest for [EMIM] TFSA and the weakest for [HMIM] FAP because the interfacial layers are better formed for the longer alkyl chain cation. This means interfacial forces are stronger, which masks the weak attractive forces.
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Affiliation(s)
- Hua Li
- Centre for Advanced Particle Processing and Transport, The University of Newcastle, Callaghan, NSW 2308, Australia
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60
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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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61
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Payal RS, Balasubramanian S. Effect of cation symmetry on the organization of ionic liquids near a charged mica surface. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:284101. [PMID: 24919885 DOI: 10.1088/0953-8984/26/28/284101] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Atomistic molecular dynamics simulations have been carried out to understand the effect of the symmetry of cations on the microscopic organization of ionic liquids near a charged mica surface. Ionic liquids with a 1,3-alkylimidazolium ([C(n)C(m)im](+)) cation and a bis(trifluoromethylsulfonyl)imide ([NTf2](-)) anion were investigated. Apart from symmetry, the length of the alkyl group attached to the cation is found to crucially determine the ion structure near the solid surface. In the first adsorbed layer, the ring planes of cations with shorter alkyl groups (less than four carbon atoms) are oriented either parallel or perpendicular to the surface. However, cations with longer alkyl tails are exclusively observed to have their ring planes parallel to the mica surface. The alkyl groups too show a similar dependence of their orientation on the tail length. Further, symmetric cations with alkyl groups of intermediate length are more highly structured at the interface than their asymmetric counterparts.
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Affiliation(s)
- Rajdeep Singh Payal
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
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62
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Sweeney J, Webber GB, Rutland MW, Atkin R. Effect of ion structure on nanoscale friction in protic ionic liquids. Phys Chem Chem Phys 2014; 16:16651-8. [DOI: 10.1039/c4cp02320j] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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64
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65
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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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66
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Smith J, Webber GB, Warr GG, Atkin R. Silica particle stability and settling in protic ionic liquids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:1506-1513. [PMID: 24450614 DOI: 10.1021/la403978b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Silica particle suspensions of 10 wt % have been investigated in the protic ionic liquids (ILs) ethylammonium nitrate (EAN), ethanolammonium nitrate (EtAN), propylammonium nitrate (PAN), and dimethylethylammonium formate (DMEAF). Static and dynamic light scattering reveal that single particles coexist in dynamic equilibrium with flocculated networks at room temperature. These types of systems are classified as weakly flocculated and are quite rare. As weakly flocculated systems generally exist only within a narrow range of conditions, the effect of temperature was probed. When temperature is increased, the thermal motion of suspended particles increases, favoring dispersion, but in ILs suspensions, heating reduces the stabilizing effect of the interfacial structure of the IL. When subjected to a small increase in temperature, particle suspensions in ILs become unstable, indicated by the absence of a peak corresponding to single particles in the light scattering data. For EAN and DMEAF, further increasing temperatures above 40 °C returns the systems to a weakly flocculated state in which thermal energy is sufficient to break particles away from aggregates. Weakly flocculated suspensions in EAN and EtAN settle more rapidly than predicted by the Stokes equation, as the particles spend a significant portion of time in large, rapidly settling flocs. Surprisingly, suspensions in PAN and DMEAF settle slower than predicted. Oscillatory rheology indicates that these suspensions are viscoelastic, due to a persistent, long-range structure in the suspension that slows settling. In aggregated systems, settling is very rapid.
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Affiliation(s)
- Jacob Smith
- Priority Research Centre for Advanced Particle Processing and Transport, The University of Newcastle , Callaghan, NSW 2308, Australia
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67
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Shimizu K, Bernardes CE, Lopes JNC. The complex structure of ionic liquids at an atomistic level: from “red-and-greens” to charge templates. PURE APPL CHEM 2014. [DOI: 10.1515/pac-2014-5021] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
In this article, we discuss how the relation between interactions and structure in ionic liquids (ILs) can be probed at a molecular level using ab initio and molecular dynamics (MD) methodologies. The first part of the discussion will focus on the unique and complex properties of ILs as pure substances including the existence of an extended and flexible polar network and the possibility of a second nanosegregated subphase containing the nonpolar residues of the molecular ions that constitute some ILs. The discussion will then be extended to IL plus molecular species mixtures/solutions. In this context the concept of ILs as charge templates for the electronic make-up of the molecular species will be analyzed at length. Finally, that concept will be extended to ILs adsorbed over solid substrates.
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68
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Preferential Formation of Layered Structure of Ionic Liquid at Ionic Liquid Aqueous Solution / Graphite Electrode Interfaces Observed by Frequency-Modulation Atomic Force Microscopy. E-JOURNAL OF SURFACE SCIENCE AND NANOTECHNOLOGY 2014. [DOI: 10.1380/ejssnt.2014.89] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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69
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ICHII T, NEGAMI M, FUJIMURA M, MURASE K, SUGIMURA H. Structural Analysis of Ionic-liquid/Organic-monolayer Interface by Phase Modulation Atomic Force Microscopy Utilizing a Quartz Tuning Fork Sensor. ELECTROCHEMISTRY 2014. [DOI: 10.5796/electrochemistry.82.380] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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70
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Federici Canova F, Matsubara H, Mizukami M, Kurihara K, Shluger AL. Shear dynamics of nanoconfined ionic liquids. Phys Chem Chem Phys 2014; 16:8247-56. [DOI: 10.1039/c4cp00005f] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The solid–liquid interfacial structure of ILs, determined by their molecular shape, results in different flow dynamics and friction under shear stress.
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Affiliation(s)
| | - Hiroki Matsubara
- Department of Applied Chemistry
- School of Engineering
- Tohoku University
- Sendai 980-8579, Japan
| | - Masashi Mizukami
- Institute of Multidisciplinary Research for Advanced Materials
- Tohoku University
- Sendai 980-8577, Japan
| | - Kazue Kurihara
- Advanced Institute for Materials Research
- Tohoku University
- Sendai 980-8577, Japan
- Institute of Multidisciplinary Research for Advanced Materials
- Tohoku University
| | - Alexander L. Shluger
- Advanced Institute for Materials Research
- Tohoku University
- Sendai 980-8577, Japan
- Department of Physics and Astronomy and the London Centre for Nanotechnology
- University College London
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71
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Smith JA, Webber GB, Warr GG, Atkin R. Rheology of protic ionic liquids and their mixtures. J Phys Chem B 2013; 117:13930-5. [PMID: 24102175 DOI: 10.1021/jp407715e] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The rheological properties of five pure protic ionic liquids (ILs), ethylammonium nitrate (EAN), propylammonium nitrate (PAN), ethanolammonium nitrate (EtAN), ethylammonium formate (EAF), and dimethylethylammonium formate (DMEAF), are characterized and interpreted by considering the effects of both the H-bond network and the solvophobic nanostructure of the liquids. The results demonstrate that these effects are not, however, independent or simply additive. At 20 °C, EtAN has the highest zero shear viscosity of 156.1 mPa·s, followed by PAN (89.3 mPa·s), EAN (35.9 mPa·s), EAF (23.1 mPa·s), and DMEAF (9.8 mPa·s). The primary ammonium ILs behave as Newtonian fluids at low shear rates but shear thin at high shear. Fits to the Vogel-Fulcher-Tammann model reveal that nanostructure is not affected appreciably by temperature and that all the ILs studied are of intermediate fragility. The rheology of binary mixtures of these ILs was analyzed and used to demonstrate fundamental differences in the way IL cations and anions interact. IL mixtures containing both nitrate and formate anions resist flow more strongly than the pure liquids, which is a consequence of the difference in hydrogen bonding capacity of the anions. Mixing cations can give rise to complex behavior due to the offsetting effects of hydrogen bonding and solvophobic nanostructure formation.
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Affiliation(s)
- J A Smith
- Priority Research Centre for Advanced Particle Processing and Transport, The University of Newcastle , Callaghan, New South Wales 2308, Australia
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72
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73
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Wang Z, Priest C. Impact of nanoscale surface heterogeneity on precursor film growth and macroscopic spreading of [Rmim][NTf2] ionic liquids on mica. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:11344-11353. [PMID: 23937096 DOI: 10.1021/la402668v] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The connection between the interfacial properties of ionic liquids and their wetting behavior has been studied very little to date and not at all on heterogeneous surfaces. Therefore, we have investigated the static and dynamic wetting for a family of ionic liquids, 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, [Rmim][NTf2], on mica, where R represents an ethyl, butyl, or hexyl alkyl chain on the imidazolium ring. Spreading is impacted greatly by a precursor film that forms on both homogeneous and heterogeneous mica surfaces. Macroscopically, the initial viscous spreading of the ionic liquid droplet on bare mica occurs within seconds but is then followed by a very slow relaxation that can be closely correlated with the typical time-scales of the precursor film growth. The contact angle for [emim][NTf2] and [bmim][NTf2] relaxes from about 40° to 23° over 30 and 90 min, respectively. For [hmim][NTf2], the process takes approximately 24 h and approaches complete wetting. The thickness of the precursor films for [emim][NTf2], [bmim][NTf2], and [hmim][NTf2] were 0.53, 0.65, and 1.0 nm, respectively, according to atomic force microscopy (AFM). These values are consistent with a monolayer of ionic liquid cations on mica, rather than ion pairs. A monolayer of octadecylphosphonic acid (OPA) on mica prevents both the formation of a precursor film and the relaxation of the contact angle. However, only a partial surface coverage of ~60% OPA is required to have the same effect. Quenching of precursor film formation (and associated contact angle relaxation) is due to an increasingly connected network of OPA regions that closes the nanoscale paths of bare mica on which the precursor film can develop via surface diffusion.
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Affiliation(s)
- Zhantao Wang
- Ian Wark Research Institute, University of South Australia , Mawson Lakes, SA 5095, Australia
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74
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Pereiro AB, Pastoriza-Gallego MJ, Shimizu K, Marrucho IM, Lopes JNC, Piñeiro MM, Rebelo LPN. On the formation of a third, nanostructured domain in ionic liquids. J Phys Chem B 2013; 117:10826-33. [PMID: 23964834 DOI: 10.1021/jp402300c] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The study of solid-fluid transitions in fluorinated ionic liquids using differential scanning calorimetry, rheology, and molecular modeling techniques is an essential step toward the understanding of their dynamics and the thermodynamics and the development of potential applications. Two fluorinated ionic liquids were studied: 1-hexyl-3-methylimidazolium perfluorobutanesulfonate, HMIm(PFBu)SO3, and tetrabutylammonium perfluorobutanesulfonate, NB4(PFBu)SO3. The experimental calorimetric and rheological data were analyzed taking into account the possible mesoscale structure of the two fluorinated ionic liquids. The simulation results indicate the possible formation of three nanosegregated domains-polar, nonpolar, and fluorous-that may have a profound impact on ionic liquid research. In the case of HMIm (PFBu)SO3 the three types of mesoscopic domains can act as interchangeable jigsaw pieces enabling the formation of multiple types of crystals and inducing the observed calorimetry and rheological trends.
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Affiliation(s)
- Ana B Pereiro
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa , Apartado 127, 2780-157 Oeiras, Portugal
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75
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Bhat MA, Jha SK. Anomalous fluctuations in current transient at glassy carbon|room temperature ionic liquid interface. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.04.042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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76
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Peñalber CY, Baker GA, Baldelli S. Sum Frequency Generation Spectroscopy of Imidazolium-Based Ionic Liquids with Cyano-Functionalized Anions at the Solid Salt–Liquid Interface. J Phys Chem B 2013; 117:5939-49. [DOI: 10.1021/jp4019074] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chariz Y. Peñalber
- Department of Chemistry, University of Houston, Houston, Texas 77204-5003, United
States
| | - Gary A. Baker
- Department of Chemistry, University of Missouri—Columbia, Columbia, Missouri,
65211-7600, United States
| | - Steven Baldelli
- Department of Chemistry, University of Houston, Houston, Texas 77204-5003, United
States
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77
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Smith AM, Lovelock KRJ, Gosvami NN, Licence P, Dolan A, Welton T, Perkin S. Monolayer to Bilayer Structural Transition in Confined Pyrrolidinium-Based Ionic Liquids. J Phys Chem Lett 2013; 4:378-382. [PMID: 26281727 DOI: 10.1021/jz301965d] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Ionic liquids can be intricately nanostructured in the bulk and at interfaces resulting from a delicate interplay between interionic and surface forces. Here we report the structuring of a series of dialkylpyrrolidinium-based ionic liquids induced by confinement. The ionic liquids containing cations with shorter alkyl chain substituents form alternating cation-anion monolayer structures on confinement to a thin film, whereas a cation with a longer alkyl chain substituent leads to bilayer formation. The crossover from monolayer to bilayer structure occurs between chain lengths of n = 8 and 10 for these pyrrolidinium-based ionic liquids. The bilayer structure for n = 10 involves full interdigitation of the alkyl chains; this is in contrast with previous observations for imidazolium-based ionic liquids. The results are pertinent to these liquids' application as electrolytes, where the electrolyte is confined inside the pores of a nanoporous electrode, for example, in devices such as supercapacitors or batteries.
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Affiliation(s)
- Alexander M Smith
- †Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Kevin R J Lovelock
- ‡Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom
| | - Nitya Nand Gosvami
- §Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, 220 South 33rd Street, Philadelphia, Pennsylvania 19104, United States
| | - Peter Licence
- ∥School of Chemistry, The University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Andrew Dolan
- ‡Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom
| | - Tom Welton
- ‡Department of Chemistry, Imperial College London, London SW7 2AZ, United Kingdom
| | - Susan Perkin
- †Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
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78
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Bhat MA, Konar A, Ingole PP, Pandith AH. Unusual aspects of ion-pairing effects in room temperature ionic liquids. J PHYS ORG CHEM 2013. [DOI: 10.1002/poc.3000] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Mohsin Ahmad Bhat
- Department of Chemistry; University of Pune; Ganeshkhind Pune 411007 India
- Department of Chemistry; University of Kashmir; Srinagar 190006 India
| | - Arkaprabha Konar
- Department of Chemistry; University of Pune; Ganeshkhind Pune 411007 India
| | - Pravin P. Ingole
- Physical Chemistry and Electrochemistry; Technical University of Dresden; Bergstrasse 66b 01062 Dresden Germany
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79
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Segura JJ, Elbourne A, Wanless EJ, Warr GG, Voïtchovsky K, Atkin R. Adsorbed and near surface structure of ionic liquids at a solid interface. Phys Chem Chem Phys 2013; 15:3320-8. [DOI: 10.1039/c3cp44163f] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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80
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Li H, Rutland MW, Atkin R. Ionic liquid lubrication: influence of ion structure, surface potential and sliding velocity. Phys Chem Chem Phys 2013; 15:14616-23. [DOI: 10.1039/c3cp52638k] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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81
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Elbourne A, Sweeney J, Webber GB, Wanless EJ, Warr GG, Rutland MW, Atkin R. Adsorbed and near-surface structure of ionic liquids determines nanoscale friction. Chem Commun (Camb) 2013; 49:6797-9. [DOI: 10.1039/c3cc42844c] [Citation(s) in RCA: 61] [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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82
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Smith AM, Lovelock KRJ, Perkin S. Monolayer and bilayer structures in ionic liquids and their mixtures confined to nano-films. Faraday Discuss 2013; 167:279-92. [DOI: 10.1039/c3fd00075c] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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83
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Li H, Endres F, Atkin R. Effect of alkyl chain length and anion species on the interfacial nanostructure of ionic liquids at the Au(111)–ionic liquid interface as a function of potential. Phys Chem Chem Phys 2013; 15:14624-33. [DOI: 10.1039/c3cp52421c] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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84
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Black JM, Walters D, Labuda A, Feng G, Hillesheim PC, Dai S, Cummings PT, Kalinin SV, Proksch R, Balke N. Bias-dependent molecular-level structure of electrical double layer in ionic liquid on graphite. NANO LETTERS 2013; 13:5954-60. [PMID: 24215396 DOI: 10.1021/nl4031083] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Here we report the bias-evolution of the electrical double layer structure of an ionic liquid on highly ordered pyrolytic graphite measured by atomic force microscopy. We observe reconfiguration under applied bias and the orientational transitions in the Stern layer. The synergy between molecular dynamics simulation and experiment provides a comprehensive picture of structural phenomena and long and short-range interactions, which improves our understanding of the mechanism of charge storage on a molecular level.
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Affiliation(s)
- Jennifer M Black
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
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85
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Démery V, Dean DS, Hammant TC, Horgan RR, Podgornik R. The one-dimensional Coulomb lattice fluid capacitor. J Chem Phys 2012; 137:064901. [PMID: 22897305 DOI: 10.1063/1.4740233] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The one-dimensional Coulomb lattice fluid in a capacitor configuration is studied. The model is formally exactly soluble via a transfer operator method within a field theoretic representation of the model. The only interactions present in the model are the one-dimensional Coulomb interaction between cations and anions and the steric interaction imposed by restricting the maximal occupancy at any lattice site to one particle. Despite the simplicity of the model, a wide range of intriguing physical phenomena arise, some of which are strongly reminiscent of those seen in experiments and numerical simulations of three-dimensional ionic liquid based capacitors. Notably, we find regimes where over-screening and density oscillations are seen near the capacitor plates. The capacitance is also shown to exhibit strong oscillations as a function of applied voltage. It is also shown that the corresponding mean-field theory misses most of these effects. The analytical results are confirmed by extensive numerical simulations.
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Affiliation(s)
- Vincent Démery
- Laboratoire de Physique Théorique (IRSAMC), Université de Toulouse, UPS and CNRS, F-31062 Toulouse, France
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86
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Carstens T, Hayes R, Abedin SZE, Corr B, Webber GB, Borisenko N, Atkin R, Endres F. In situ STM, AFM and DTS study of the interface 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate/Au(111). Electrochim Acta 2012. [DOI: 10.1016/j.electacta.2012.01.111] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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87
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Endres F, Borisenko N, El Abedin SZ, Hayes R, Atkin R. The interface ionic liquid(s)/electrode(s): in situ STM and AFM measurements. Faraday Discuss 2012; 154:221-33; discussion 313-33, 465-71. [PMID: 22455022 DOI: 10.1039/c1fd00050k] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The structure of the interfacial layer(s) between the extremely pure air- and water-stable ionic liquid 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl) trifluorophosphate and Au(111) has been investigated using in situ scanning tunneling microscopy (STM) at electrode potentials more positive than the open circuit potential. The in situ STM measurements show that layers/islands form with increasing electrode potential. According to recently published atomic force microscopy (AFM) data the anion is adsorbed even at low anodic overvoltages and adsorption becomes slightly stronger with increasing electrode potential. Furthermore, the number of interfacial layers increases with increasing electrode potential. The present discussion paper shows that these layers are not uniform and have a structure on the nanoscale, supporting earlier results that the interface electrode/ionic liquid is highly complex. It is also shown that the addition of solutes changes this structure considerably. AFM results reveal that in the pure liquid, interfacial layers lead to a repulsive force but the addition of 10 wt% of LiCl leads to an attractive force close to the surface. These preliminary results show that solutes strongly alter the interfacial structure of the ionic liquid/ electrode interface.
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Affiliation(s)
- Frank Endres
- Institute of Particle Technology, Clausthal University of Technology, Arnold-Sommerfeld-Strasse 6, 38678 Clausthal-Zellerfeld, Germany.
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88
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Peñalber CY, Baldelli S. Observation of Charge Inversion of an Ionic Liquid at the Solid Salt-Liquid Interface by Sum Frequency Generation Spectroscopy. J Phys Chem Lett 2012; 3:844-847. [PMID: 26286408 DOI: 10.1021/jz3000917] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Sum frequency generation (SFG) vibrational spectroscopy of the ionic liquid, 1-butyl-3-methylimidazolium dicyanamide [BMIM][DCA], in contact with two different solid salt surfaces, BaF2(111) single crystal and solid NaCl{100}, are discussed in this Letter. This investigation describes the nature of an ionic liquid-(solid) salt interface using SFG, contributing a new understanding to the molecular-level interactions involved in salts, which are conceptually similar compounds (of purely ionic character) but of different physical properties (liquid versus solid at room temperature). Results show the presence of [BMIM](+) at the NaCl{100} surface and [DCA](-) at the BaF2(111) surface. [BMIM](+) cations adhere closely via Coulombic interactions to the negatively charged NaCl{100} surface, while [DCA](-) anions subsequently have a strong electrostatic affinity to the positively charged BaF2(111) surface. Ions of the ionic liquid adsorb to the solid salt surface to form a Helmholtz-like electric double layer.
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Affiliation(s)
- Chariz Y Peñalber
- Department of Chemistry, University of Houston, Houston, Texas 77204-5003, United States
| | - Steven Baldelli
- Department of Chemistry, University of Houston, Houston, Texas 77204-5003, United States
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89
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Singh Payal R, Balasubramanian S. Orientational Ordering of Ionic Liquids near a Charged Mica Surface. Chemphyschem 2012; 13:1764-71. [DOI: 10.1002/cphc.201100871] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 02/08/2012] [Indexed: 11/10/2022]
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90
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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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91
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Dragoni D, Manini N, Ballone P. Interfacial Layering of a Room-Temperature Ionic Liquid Thin Film on Mica: A Computational Investigation. Chemphyschem 2012; 13:1772-80. [DOI: 10.1002/cphc.201100947] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 02/08/2012] [Indexed: 11/06/2022]
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92
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Abstract
Over recent years the Surface Force Apparatus (SFA) has been used to carry out model experiments revealing structural and dynamic properties of ionic liquids confined to thin films. Understanding characteristics such as confinement induced ion layering and lubrication is of primary importance to many applications of ionic liquids, from energy devices to nanoparticle dispersion. This Perspective surveys and compares SFA results from several laboratories as well as simulations and other model experiments. A coherent picture is beginning to emerge of ionic liquids as nano-structured in pores and thin films, and possessing complex dynamic properties. The article covers structure, dynamics, and colloidal forces in confined ionic liquids; ionic liquids are revealed as a class of liquids with unique and useful confinement properties and pertinent future directions of research are highlighted.
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Affiliation(s)
- Susan Perkin
- Department of Chemistry, University College London, WC1H 0AJ, London, UK.
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93
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Men S, Hurisso BB, Lovelock KRJ, Licence P. Does the influence of substituents impact upon the surface composition of pyrrolidinium-based ionic liquids? An angle resolved XPS study. Phys Chem Chem Phys 2012; 14:5229-38. [DOI: 10.1039/c2cp40262a] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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94
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Yoshii K, Tsuda T, Arimura T, Imanishi A, Torimoto T, Kuwabata S. Platinum nanoparticle immobilization onto carbon nanotubes using Pt-sputtered room-temperature ionic liquid. RSC Adv 2012. [DOI: 10.1039/c2ra21243a] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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95
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Shimizu K, Pensado A, Malfreyt P, Pádua AAH, Canongia Lopes JN. 2D or not 2D: Structural and charge ordering at the solid-liquid interface of the 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate ionic liquid. Faraday Discuss 2012; 154:155-69; discussion 189-220, 465-71. [DOI: 10.1039/c1fd00043h] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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96
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Frolov AI, Kirchner K, Kirchner T, Fedorov MV. Molecular-scale insights into the mechanisms of ionic liquids interactions with carbon nanotubes. Faraday Discuss 2012; 154:235-47; discussion 313-33, 465-71. [DOI: 10.1039/c1fd00080b] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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97
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Fedorov MV, Lynden-Bell RM. Probing the neutral graphene–ionic liquid interface: insights from molecular dynamics simulations. Phys Chem Chem Phys 2012; 14:2552-6. [DOI: 10.1039/c2cp22730d] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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98
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Shen Y, Kennedy DF, Greaves TL, Weerawardena A, Mulder RJ, Kirby N, Song G, Drummond CJ. Protic ionic liquids with fluorous anions: physicochemical properties and self-assembly nanostructure. Phys Chem Chem Phys 2012; 14:7981-92. [DOI: 10.1039/c2cp40463j] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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99
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Zhang X, Zhong YX, Yan JW, Su YZ, Zhang M, Mao BW. Probing double layer structures of Au (111)-BMIPF6 ionic liquid interfaces from potential-dependent AFM force curves. Chem Commun (Camb) 2011; 48:582-4. [PMID: 22109542 DOI: 10.1039/c1cc15463j] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High quality AFM force curves are presented with detailed potential dependent layering behaviors of the ionic liquid molecules, from which charged interior and neutral exterior layers are distinguished. The electric double layer is confined within the interior layers of one to two molecular size within the potential range of up to 1 V negative of the PZC.
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Affiliation(s)
- Xiao Zhang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
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100
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Development of a Ag/Ag+ micro-reference electrode for electrochemical measurements in ionic liquids. Electrochim Acta 2011. [DOI: 10.1016/j.electacta.2011.02.055] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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