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Pontoni D, DiMichiel M, Murphy BM, Honkimäki V, Deutsch M. Ordering of ionic liquids at a charged sapphire interface: Evolution with cationic chain length. J Colloid Interface Sci 2024; 661:33-45. [PMID: 38295701 DOI: 10.1016/j.jcis.2024.01.126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 01/09/2024] [Accepted: 01/18/2024] [Indexed: 02/27/2024]
Abstract
HYPOTHESIS Room Temperature Ionic Liquids (RTILs) bulk's molecular layering dominates their structure also at the RTIL/sapphire interface, increasing the layer spacing with the cationic alkyl chain length n. However, the negatively-charged sapphire surface compresses the layers, increases the layering range, and affects the intra-layer structure in yet unknown ways. EXPERIMENTS X-ray reflectivity (XR) off the RTIL/sapphire interface, for a broad homologous RTIL series 1-alkyl-3-methylimidazolium bis(trifluoromethansulfonyl)imide, hitherto unavailable for any RTIL. FINDINGS RTIL layers against the sapphire, exhibit two spacings: da and db. da is n-varying, follows the behavior of the bulk spacing but exhibits a downshift, thus showing significant layer compression, and over twofold polar slab thinning. The latter suggests exclusion of anions from the interfacial region due to the negative sapphire charging by x-ray-released electrons. The layering range is larger than the bulk's. db is short and near n-independent, suggesting polar moieties' layering, the coexistence mode of which with the da-spaced layering is unclear. Comparing the present layering with the bulk's and the RTIL/air interface's provides insight into the Coulomb and dispersion interaction balance dominating the RTIL's structure and the impact thereon of the presence of a charged solid interface.
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Affiliation(s)
- Diego Pontoni
- ESRF - The European Synchrotron, 71 Avenue des Martyrs, 38043 Grenoble, France
| | - Marco DiMichiel
- ESRF - The European Synchrotron, 71 Avenue des Martyrs, 38043 Grenoble, France
| | - Bridget M Murphy
- Institute of Experimental and Applied Physics, Kiel University, Kiel D-24098, Germany; Ruprecht-Haensel Laboratory, Kiel University, Kiel D-24118, Germany
| | - Veijo Honkimäki
- ESRF - The European Synchrotron, 71 Avenue des Martyrs, 38043 Grenoble, France
| | - Moshe Deutsch
- Physics Dept. & Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan, Israel.
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2
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Hemmeter D, Paap U, Wellnhofer N, Gezmis A, Kremitzl D, Wasserscheid P, Steinrück HP, Maier F. Understanding the Buoy Effect of Surface-Enriched Pt Complexes in Ionic Liquids: A Combined ARXPS and Pendant Drop Study. Chemphyschem 2023:e202300612. [PMID: 37738406 DOI: 10.1002/cphc.202300612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 09/22/2023] [Accepted: 09/22/2023] [Indexed: 09/24/2023]
Abstract
Recently, we demonstrated that Pt catalyst complexes dissolved in the ionic liquid (IL) [C4 C1 Im][PF6 ] can be deliberately enriched at the IL surface by introducing perfluorinated substituents, which act like buoys dragging the metal complex towards the surface. Herein, we extend our previous angle-resolved X-ray photoelectron spectroscopy (ARXPS) studies at complex concentrations between 30 and 5 %mol down to 1 %mol and present complementary surface tension pendant drop (PD) measurements under ultraclean vacuum conditions. This combination allows for connecting the microscopic information on the IL/gas interface derived from ARXPS with the macroscopic property surface tension. The surface enrichment of the Pt complexes is found to be most pronounced at 1 %mol . It also displays a strong temperature dependence, which was not observed for 5 %mol and above, where the surface is already saturated with the complex. The surface enrichment deduced from ARXPS is also reflected by the pronounced decrease in surface tension with increasing concentration of the catalyst. We furthermore observe by ARXPS and PD a much stronger surface affinity of the buoy-complex as compared to the free ligands in solution. Our results are highly interesting for an optimum design of IL-based catalyst systems with large contact areas to the surrounding reactant/product phase, such as in supported IL phase (SILP) catalysis.
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Affiliation(s)
- Daniel Hemmeter
- Lehrstuhl für Physikalische Chemie 2, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany
| | - Ulrike Paap
- Lehrstuhl für Physikalische Chemie 2, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany
| | - Nicolas Wellnhofer
- Lehrstuhl für Physikalische Chemie 2, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany
| | - Afra Gezmis
- Lehrstuhl für Physikalische Chemie 2, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany
| | - Daniel Kremitzl
- Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany
| | - Peter Wasserscheid
- Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany
- Forschungszentrum Jülich, Helmholtz-Institute Erlangen-Nürnberg for Renewable Energies (IEK 11), Cauerstraße 1, 91058, Erlangen, Germany
| | - Hans-Peter Steinrück
- Lehrstuhl für Physikalische Chemie 2, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany
| | - Florian Maier
- Lehrstuhl für Physikalische Chemie 2, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany
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3
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Hossain MI, Adhikari L, Baker GA, Blanchard GJ. Relating the Induced Free Charge Density Gradient in a Room-Temperature Ionic Liquid to Molecular-Scale Organization. J Phys Chem B 2023; 127:1780-1788. [PMID: 36790441 DOI: 10.1021/acs.jpcb.2c07745] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
We report on dilution-dependent changes in the local environments of chromophores incorporated into room-temperature ionic liquid (RTIL)-molecular solvent binary systems where the ionic liquid cation and molecular solvent possess the same alkyl chain length. We have used the RTIL 1-decyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (DMPyrr+TFSI-) and the molecular solvent 1-decanol. Perylene was used as a non-polar probe, and cresyl violet (CV+) was used as a polar probe chromophore. We observe that in both regions there is a change in the chromophore local environments with increasing 1-decanol content. The changes in the nonpolar regions of the binary RTIL-molecular solvent system occur at a lower 1-decanol concentration than changes in the polar regions. Both chromophores reorient as oblate rotors in this binary system, allowing detailed information on the relative values of the Cartesian components of the rotational diffusion constants to be extracted from the experimental data. The induced free charge density gradient, ρf, known to exist in RTILs, persists to high 1-decanol content (1-decanol mole fraction of 0.75), with the structural details of the gradient being reflected in depth-dependent changes in the Cartesian components of the rotational diffusion constants of CV+. This is the first time that changes in molecular organization have been correlated with ρf.
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Affiliation(s)
- Md Iqbal Hossain
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Laxmi Adhikari
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, United States
| | - Gary A Baker
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, United States
| | - G J Blanchard
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
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4
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Hemmeter D, Kremitzl D, Schulz PS, Wasserscheid P, Maier F, Steinrück HP. The Buoy Effect: Surface Enrichment of a Pt Complex in IL Solution by Ligand Design. Chemistry 2023; 29:e202203325. [PMID: 36446030 PMCID: PMC10107114 DOI: 10.1002/chem.202203325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 11/28/2022] [Accepted: 11/29/2022] [Indexed: 11/30/2022]
Abstract
The targeted enrichment of a Pt complex with an ionic liquid (IL)-derived ligand system in IL solution is demonstrated by using angle-resolved X-ray photoelectron spectroscopy. When the ligand system is complemented with fluorinated side chains, the complex accumulates strongly at the IL/gas interface, while in an equivalent solution of a complex without these substituents no such effect could be observed. This buoy-like behavior induces strong population of the complex at the outermost molecular layer close to surface saturation, which was studied over a range from 5 to 30 %mol . The surface enrichment was found to be most efficient at the lowest concentration, which is particularly favorable for catalytic applications such as supported ionic-liquid-phase (SILP) catalysis.
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Affiliation(s)
- Daniel Hemmeter
- Lehrstuhl für Physikalische Chemie 2, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany
| | - Daniel Kremitzl
- Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany
| | - Peter S Schulz
- Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany
| | - Peter Wasserscheid
- Lehrstuhl für Chemische Reaktionstechnik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany.,Forschungszentrum Jülich GmbH, Helmholtz-Institute Erlangen-Nürnberg for Renewable Energy (IEK-11), Egerlandstr. 3, 91058, Erlangen, Germany
| | - Florian Maier
- Lehrstuhl für Physikalische Chemie 2, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany
| | - Hans-Peter Steinrück
- Lehrstuhl für Physikalische Chemie 2, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstr. 3, 91058, Erlangen, Germany
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5
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Karunaratne W, Zhao M, Castner EW, Margulis CJ. Vacuum Interfacial Structure and X-ray Reflectivity of Imidazolium-Based Ionic Liquids with Perfluorinated Anions from a Theory and Simulations Perspective. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2022; 126:13936-13945. [PMID: 36017361 PMCID: PMC9394757 DOI: 10.1021/acs.jpcc.2c03311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 07/22/2022] [Indexed: 06/15/2023]
Abstract
We report studies of the vacuum interfacial structure of a series of 1-methyl-3-alkylimidazolium bis(perfluoroalkanesulfonyl)imide ionic liquids (ILs) and predict and explain their Fresnel-normalized X-ray reflectivity. To better interpret the results, we use a theory we recently developed dubbed "the peaks and antipeaks analysis of reflectivity" which splits the overall signal into that of different pair subcomponents. Whereas the overall reflectivity signal is not very informative, the peak and trough intensities for the pair subcomponents provide rich information for analysis. When species containing cationic alkyl or anionic fluoroalkyl tails are present at the interface, a tail layer is found next to a vacuum, and this tail layer can be composed of both alkyl and fluoroalkyl moieties. To maintain the positive-negative alternation of charged groups, alkyl and fluoroalkyl tails must necessarily be nearby and cannot segregate. Charged groups are found in the subsequent layer just below the interface and arranged to achieve lateral charge neutrality. In general, fluctuations at and away from the interface are based on polarity (i.e., heads and tails) and not on charge; when there are no significant alkyl or fluoroalkyl moieties in the IL, atomic density fluctuations away from the interface are small and appear to exist for the purpose of achieving lateral charge balance. For all the systems reported here, the persistence length of density fluctuations does not go beyond ∼7 nm.
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Affiliation(s)
| | - Man Zhao
- Department
of Chemistry and Chemical Biology, Rutgers,
The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Edward W. Castner
- Department
of Chemistry and Chemical Biology, Rutgers,
The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Claudio J. Margulis
- Department
of Chemistry, University of Iowa, Iowa City, Iowa 52242, United States
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6
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Bomhardt K, Schneider P, Glaser T, Dürr M. Surface Properties of Ionic Liquids: A Mass Spectrometric View Based on Soft Cluster-Induced Desorption. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:974-980. [PMID: 35579531 DOI: 10.1021/jasms.2c00038] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Desorption/ionization induced by neutral clusters (DINeC) in combination with mass spectrometry (MS) was used for the investigation of the molecular composition of the surface of ionic liquids (IL). Based on the surface sensitivity of DINeC-MS, accumulation of either cations or anions was discriminated on the surface of bulk IL depending on the molecular structure of the IL components. In particular, cations with long alkyl chains aggregate on the surface, but this tendency is more reduced the larger the respective anion is; in the case of larger anions and smaller cations, it can be even reversed. For thin layers of IL, the ratio between cations and anions as detected in the mass spectra was found to be further influenced by the substrate surface.
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Affiliation(s)
- Karolin Bomhardt
- Institut für Angewandte Physik and Zentrum für Materialforschung, Justus-Liebig-Universität Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany
| | - Pascal Schneider
- Institut für Angewandte Physik and Zentrum für Materialforschung, Justus-Liebig-Universität Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany
| | - Timo Glaser
- Institut für Angewandte Physik and Zentrum für Materialforschung, Justus-Liebig-Universität Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany
| | - Michael Dürr
- Institut für Angewandte Physik and Zentrum für Materialforschung, Justus-Liebig-Universität Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen, Germany
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7
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Yue K, Doherty B, Acevedo O. Comparison between Ab Initio Molecular Dynamics and OPLS-Based Force Fields for Ionic Liquid Solvent Organization. J Phys Chem B 2022; 126:3908-3919. [PMID: 35594504 DOI: 10.1021/acs.jpcb.2c01636] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OPLS-based force fields (FFs) have been shown to provide accurate bulk-phase properties for a wide variety of imidazolium-based ionic liquids (ILs). However, the ability of OPLS to reproduce an IL solvent structure is not as well-validated given the relative lack of high-level theoretical or experimental data available for comparison. In this study, ab initio molecular dynamics (AIMD) simulations were performed for three widely used ILs: the 1-butyl-3-methylimidazolium cation with chloride, tetrafluoroborate, or hexafluorophosphate anions, that is, [BMIM][Cl], [BMIM][BF4], and [BMIM][PF6], respectively, as a basis for further assessment of two unique IL FFs: the ±0.8 charge-scaled OPLS-2009IL FF and the OPLS-VSIL FF. The OPLS-2009IL FF employs a traditional all-atom functional form, whereas the OPLS-VSIL FF was developed using a virtual site that offloads negative charge to inside the plane of the ring with careful attention given to reproducing hydrogen bonding. Detailed comparisons between AIMD and the OPLS FFs were made based on radial distribution functions (RDFs), combined distribution functions (CDFs), and spatial distribution functions (SDFs) to examine cation-anion interactions and π+-π+ stacking between the imidazolium rings. While both FFs were able to correctly capture the general solvent structure of these popular ILs, the OPLS-VSIL FF quantitatively reproduced interaction distances more accurately. In addition, this work provides further insights into the different short- and long-range structure patterns of these popular ILs.
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Affiliation(s)
- Kun Yue
- Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
| | - Brian Doherty
- Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
| | - Orlando Acevedo
- Department of Chemistry, University of Miami, Coral Gables, Florida 33146, United States
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8
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Stoffel TD, Haskins JB, Lawson JW, Markutsya S. Coarse-Grained Dynamically Accurate Simulations of Ionic Liquids: [pyr14][TFSI] and [EMIM][BF 4]. J Phys Chem B 2022; 126:1819-1829. [PMID: 35171594 DOI: 10.1021/acs.jpcb.1c08107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this work, coarse-grained (CG) models for two different sets of ionic liquids were developed from atomistic molecular dynamics (MD) reference systems, expanding their system size and time duration capabilities. The bonded force field of the CG systems was built using harmonic oscillator potential (HOP) fitting, while the nonbonded force field was generated with the multiscale coarse-graining (MS-CG) approach based on force matching. The dynamics of each system were corrected using the probability distribution function-based coarse-grained molecular dynamics (PDF-based CGMD) method. The structure and dynamics of each system were proven to match reference system data at two temperature scales. CG models and force fields for these liquids were developed to exemplify a general purpose methodology for producing MD results of ionic liquids and other fluids with accurate structural as well as dynamic properties. As an application, developed ionic liquids CG models were then applied to study vacuum-interface interaction. Density profile results of vacuum-interface exposure show significant deviation from bulk behavior. At the interface, multilayer ordering of ionic liquids is predicted to be similar to those observed from an experimental work. This ordering is intensified by decreasing temperature and use of the PDF-based CGMD method as opposed to conventional CG methods.
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Affiliation(s)
- Tyler D Stoffel
- Department of Mechanical Engineering, University of Kentucky, Lexington, Kentucky 40506, United States
| | - Justin B Haskins
- Thermal Protections Branch, NASA Ames Research Center, Moffett Field, California 94035, United States
| | - John W Lawson
- Intelligent Systems Division, NASA Ames Research Center, Moffett Field, California 94035, United States
| | - Sergiy Markutsya
- Department of Mechanical Engineering, University of Kentucky, Paducah, Kentucky 42001, United States
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9
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WATANABE Y, TAKEUCHI Y, TAKI M, MIZUTANI H, IWASAKI M. Physicochemical Properties of Bis(fluorosulfonyl)amide-Based Ionic Liquids Mixed with Mg and Sr Doped Cubic Li<sub>7</sub>La<sub>3</sub>Zr<sub>2</sub>O<sub>12</sub> Powder. ELECTROCHEMISTRY 2022. [DOI: 10.5796/electrochemistry.22-00070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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10
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Nemoto F, Nakamura SY, Abe H. Surface structure of the mixture of 1-alkyl-3-methylimidazolium iodide and polyiodide observed by surface tension measurement and X-ray reflectivity. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.116381] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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11
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Zhang S, Nishi N, Katakura S, Sakka T. Evaluation of static differential capacitance at the [C 4mim +][TFSA -]/electrode interface using molecular dynamics simulation combined with electrochemical surface plasmon resonance measurements. Phys Chem Chem Phys 2021; 23:13905-13917. [PMID: 34132289 DOI: 10.1039/d1cp01435h] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Molecular dynamic (MD) simulations have been performed for 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([C4mim+][TFSA-]), an ionic liquid (IL), on a charged graphene electrode to achieve the quantitative analysis of the static differential capacitance using the electrochemical surface plasmon resonance (ESPR). The MD simulations have provided the surface charge density on the electrode and ionic distributions in the electric double layer, both of which are indispensable for the evaluation of static differential capacitance using ESPR but are difficult to be measured by experimental techniques. This approach has allowed the quantitative analysis and explanation of the SPR angle shift in ESPR. The major contribution to the SPR angle shift is found to be the change in ionic concentrations of the first ionic layer on the electrode, owing to higher polarizabilities of ions in the first ionic layer than those in the overlayers. Moreover, the ionic orientation on the electrode and ionic multilayer structure have also been investigated in detail. The butyl group of C4mim+ in the first ionic layer is found to provide extra room for C4mim+ in the second ionic layer but exclude TFSA-, which affects the interval and regularity of ionic multilayers.
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Affiliation(s)
- Shiwei Zhang
- Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan.
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12
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Basouli H, Mozaffari F, Eslami H. Atomistic insights into structure, ion-pairing and ionic conductivity of 1-ethyl-3-methylimidazolium methylsulfate [Emim][MeSO4] ionic liquid from molecular dynamics simulation. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115803] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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13
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Wang Y, Parvis F, Hossain MI, Ma K, Jarošová R, Swain GM, Blanchard GJ. Local and Long-Range Organization in Room Temperature Ionic Liquids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:605-615. [PMID: 33411540 DOI: 10.1021/acs.langmuir.9b03995] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Room temperature ionic liquids (RTILs) have a wide range of current and potential applications, in areas ranging from supercapacitor energy storage to sequestration of toxic gas phase species and use as reusable solvents for selected organic reactions. All these applications stem from their unique physical and chemical properties, which remain understood to only a limited extent. Among the issues of greatest importance is the extent to which RTILs exist as dissociated ionic species and the length scales over which some types of organizations are seen to exist in them. In this Invited Feature Article, we review the current understanding of organization in this family of materials, where opportunities lie in terms of deepening our understanding, and what potential applications would benefit from gaining such knowledge.
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Affiliation(s)
- Yufeng Wang
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, Michigan 48824, United States
| | - Fatemeh Parvis
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, Michigan 48824, United States
| | - Md Iqbal Hossain
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, Michigan 48824, United States
| | - Ke Ma
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, Michigan 48824, United States
| | - Romana Jarošová
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, Michigan 48824, United States
| | - Greg M Swain
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, Michigan 48824, United States
| | - Gary J Blanchard
- Department of Chemistry, Michigan State University, 578 S. Shaw Lane, East Lansing, Michigan 48824, United States
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14
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Meusel M, Lexow M, Gezmis A, Bayer A, Maier F, Steinrück HP. Growth of Multilayers of Ionic Liquids on Au(111) Investigated by Atomic Force Microscopy in Ultrahigh Vacuum. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:13670-13681. [PMID: 33156635 PMCID: PMC7676296 DOI: 10.1021/acs.langmuir.0c02596] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 10/20/2020] [Indexed: 06/11/2023]
Abstract
Understanding the growth of ultrathin films of ionic liquids (ILs) on metal surfaces is of highest relevance for a variety of applications. We present a detailed study of the growth of the wetting layer and successive multilayers of 1,3-dimethylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C1C1Im][Tf2N]) on Au(111). By atomic force microscopy (AFM) in ultrahigh vacuum, we follow the temperature-dependent behavior between 110 and 300 K at defined coverages. We initially observe the formation of a wetting layer with a thickness of ∼0.37 nm with anions and cations arranged in a checkerboard structure. Stable AFM imaging up to 280 K allows us to follow the IL growing on top of the wetting layer in bilayers with an average thickness of ∼0.71 nm, that is, double the height of the wetting layer, in a bilayer-by-bilayer fashion. This growth behavior is independently confirmed from the surface morphology, as deduced from AFM and angle-resolved X-ray photoelectron spectroscopy. High-resolution AFM images at 110 K allow for identifying the molecular surface structure of the bilayers as a striped phase, which is one of the phases also seen for the wetting layer (Meusel, M.; Lexow, M.; Gezmis, A.; Schotz, S.; Wagner, M.; Bayer, A.; Maier, F.; Steinrück, H. P. Atomic Force and Scanning Tunneling Microscopy of Ordered Ionic Liquid Wetting Layers from 110 K up to Room Temperature. ACS Nano 2020, 14, 9000-9010).
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Affiliation(s)
- Manuel Meusel
- Lehrstuhl für Physikalische
Chemie II, Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
| | - Matthias Lexow
- Lehrstuhl für Physikalische
Chemie II, Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
| | - Afra Gezmis
- Lehrstuhl für Physikalische
Chemie II, Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
| | - Andreas Bayer
- Lehrstuhl für Physikalische
Chemie II, Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
| | - Florian Maier
- Lehrstuhl für Physikalische
Chemie II, Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
| | - Hans-Peter Steinrück
- Lehrstuhl für Physikalische
Chemie II, Universität Erlangen-Nürnberg, Egerlandstrasse 3, 91058 Erlangen, Germany
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15
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Meusel M, Lexow M, Gezmis A, Schötz S, Wagner M, Bayer A, Maier F, Steinrück HP. Atomic Force and Scanning Tunneling Microscopy of Ordered Ionic Liquid Wetting Layers from 110 K up to Room Temperature. ACS NANO 2020; 14:9000-9010. [PMID: 32609482 PMCID: PMC7391993 DOI: 10.1021/acsnano.0c03841] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 07/01/2020] [Indexed: 05/31/2023]
Abstract
Ionic liquids (ILs) are used as ultrathin films in many applications. We studied the nanoscale arrangement within the first layer of 1,3-dimethylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C1C1Im] [Tf2N]) on Au(111) between 400 and 110 K in ultrahigh vacuum by scanning tunneling and noncontact atomic force microscopy with molecular resolution. Compared to earlier studies on similar ILs, a different behavior is observed, which we attribute to the small size and symmetrical shape of the cation: (a) In both AFM and STM only the anions are imaged; (b) only long-range-ordered but no amorphous phases are observed; (c) the hexagonal room-temperature phase melts 30-50 K above the IL's bulk melting point; (d) at 110 K, striped and hexagonal superstructures with two and three ion pairs per unit cell, respectively, are found. AFM turned out to be more stable at higher temperature, while STM revealed more details at low temperature.
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Affiliation(s)
- Manuel Meusel
- Lehrstuhl
für Physikalische Chemie II, Universität
Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
| | - Matthias Lexow
- Lehrstuhl
für Physikalische Chemie II, Universität
Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
| | - Afra Gezmis
- Lehrstuhl
für Physikalische Chemie II, Universität
Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
| | - Simon Schötz
- Lehrstuhl
für Physikalische Chemie II, Universität
Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
| | - Margareta Wagner
- Lehrstuhl
für Physikalische Chemie II, Universität
Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
- Institute
of Applied Physics, TU Wien, Wiedner Hauptstraße 8-10/134, 1040 Vienna, Austria
| | - Andreas Bayer
- Lehrstuhl
für Physikalische Chemie II, Universität
Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
| | - Florian Maier
- Lehrstuhl
für Physikalische Chemie II, Universität
Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
| | - Hans-Peter Steinrück
- Lehrstuhl
für Physikalische Chemie II, Universität
Erlangen-Nürnberg, Egerlandstraße 3, 91058 Erlangen, Germany
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16
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Wang YL, Li B, Sarman S, Mocci F, Lu ZY, Yuan J, Laaksonen A, Fayer MD. Microstructural and Dynamical Heterogeneities in Ionic Liquids. Chem Rev 2020; 120:5798-5877. [PMID: 32292036 PMCID: PMC7349628 DOI: 10.1021/acs.chemrev.9b00693] [Citation(s) in RCA: 192] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Indexed: 12/11/2022]
Abstract
Ionic liquids (ILs) are a special category of molten salts solely composed of ions with varied molecular symmetry and charge delocalization. The versatility in combining varied cation-anion moieties and in functionalizing ions with different atoms and molecular groups contributes to their peculiar interactions ranging from weak isotropic associations to strong, specific, and anisotropic forces. A delicate interplay among intra- and intermolecular interactions facilitates the formation of heterogeneous microstructures and liquid morphologies, which further contributes to their striking dynamical properties. Microstructural and dynamical heterogeneities of ILs lead to their multifaceted properties described by an inherent designer feature, which makes ILs important candidates for novel solvents, electrolytes, and functional materials in academia and industrial applications. Due to a massive number of combinations of ion pairs with ion species having distinct molecular structures and IL mixtures containing varied molecular solvents, a comprehensive understanding of their hierarchical structural and dynamical quantities is of great significance for a rational selection of ILs with appropriate properties and thereafter advancing their macroscopic functionalities in applications. In this review, we comprehensively trace recent advances in understanding delicate interplay of strong and weak interactions that underpin their complex phase behaviors with a particular emphasis on understanding heterogeneous microstructures and dynamics of ILs in bulk liquids, in mixtures with cosolvents, and in interfacial regions.
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Affiliation(s)
- Yong-Lei Wang
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Bin Li
- School
of Chemical Engineering and Technology, Sun Yat-sen University, Zhuhai 519082, P. R. China
| | - Sten Sarman
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Francesca Mocci
- Department
of Chemical and Geological Sciences, University
of Cagliari, I-09042 Monserrato, Italy
| | - Zhong-Yuan Lu
- State
Key Laboratory of Supramolecular Structure and Materials, Institute
of Theoretical Chemistry, Jilin University, Changchun 130021, P. R. China
| | - Jiayin Yuan
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Aatto Laaksonen
- Department
of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
- State
Key Laboratory of Materials-Oriented and Chemical Engineering, Nanjing Tech University, Nanjing 210009, P. R. China
- Centre of
Advanced Research in Bionanoconjugates and Biopolymers, Petru Poni Institute of Macromolecular Chemistry Aleea Grigore Ghica-Voda, 41A, 700487 Iasi, Romania
- Department
of Engineering Sciences and Mathematics, Division of Energy Science, Luleå University of Technology, SE-97187 Luleå, Sweden
| | - Michael D. Fayer
- Department
of Chemistry, Stanford University, Stanford, California 94305, United States
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17
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Khaknejad Z, Mehdipour N, Eslami H. Molecular Dynamics Simulation of the Ionic Liquid 1-n-Butyl-3-Methylimidazolium Methylsulfate [Bmim][MeSO 4 ]: Interfacial Properties at the Silica and Vacuum Interfaces. Chemphyschem 2020; 21:1134-1145. [PMID: 32255269 DOI: 10.1002/cphc.202000197] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 03/29/2020] [Indexed: 11/09/2022]
Abstract
Molecular dynamics simulations are done to investigate the structure and dynamics of a thin [Bmim][MeO4 ] film in contact with a hydroxylated silica surface on one side and with vacuum on the other. An examination of the microscopic structure of ionic liquid (IL) film shows that strong layered anionic/cationic structures are formed at both interfaces. At the silica interface, the imidazolium rings are closer to the silica surface (compared to anions) and are coplanar with it. At the vacuum interface, the charged imidazolium ring more concentrates in the interior of the film, but the butyl side chain stretches out toward the vacuum interface. While there exists an excess concentration of the cations at the silica interface, at the vacuum interface an excess concentration of anions (dissolved in the butyl chain) is found. The influence of the interface on the dynamical properties is shown to depend on their time scales. A short-time dynamical property, such as hydrogen bond formation is not noticeably perturbed at the interface. In contrary, long-time properties such as ion-pair formation/rupture and translation of ions across the film are largely decelerated at the silica interface but are accelerate at the vacuum interface. Our findings indicate that the structural relaxation time of ion-pairs, is comparable to diffusion time scale in the IL film. Therefore, ion-pairs are not stable species; the IL is composed of short-lived ion-pairs and freely diffusing ions. However, the structural relaxation times of ion-pairs is still long enough (comparable to the time scale of diffusion) to conclude that correlated motions of counterions influence the macroscopic properties of IL, such as diffusion and ionic conductivity. In this respect, we have shown that correcting the Nernst-Einstein equation for the joint translation of ion-pairs considerably improves the accuracy of calculated ionic conductivities.
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Affiliation(s)
- Zeynab Khaknejad
- Department of Chemistry, College of Sciences, Persian Gulf University, Boushehr, 75168, Iran
| | - Nargess Mehdipour
- Department of Chemistry, College of Sciences, Persian Gulf University, Boushehr, 75168, Iran
| | - Hossein Eslami
- Department of Chemistry, College of Sciences, Persian Gulf University, Boushehr, 75168, Iran
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18
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19
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Weiss H, Cheng HW, Mars J, Li H, Merola C, Renner FU, Honkimäki V, Valtiner M, Mezger M. Structure and Dynamics of Confined Liquids: Challenges and Perspectives for the X-ray Surface Forces Apparatus. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:16679-16692. [PMID: 31614087 PMCID: PMC6933819 DOI: 10.1021/acs.langmuir.9b01215] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 10/15/2019] [Indexed: 05/21/2023]
Abstract
The molecular-scale structure and dynamics of confined liquids has increasingly gained relevance for applications in nanotechnology. Thus, a detailed knowledge of the structure of confined liquids on molecular length scales is of great interest for fundamental and applied sciences. To study confined structures under dynamic conditions, we constructed an in situ X-ray surface forces apparatus (X-SFA). This novel device can create a precisely controlled slit-pore confinement down to dimensions on the 10 nm scale by using a cylinder-on-flat geometry for the first time. Complementary structural information can be obtained by simultaneous force measurements and X-ray scattering experiments. The in-plane structure of liquids parallel to the slit pore and density profiles perpendicular to the confining interfaces are studied by X-ray scattering and reflectivity. The normal load between the opposing interfaces can be modulated to study the structural dynamics of confined liquids. The confinement gap distance is tracked simultaneously with nanometer precision by analyzing optical interference fringes of equal chromatic order. Relaxation processes can be studied by driving the system out of equilibrium by shear stress or compression/decompression cycles of the slit pore. The capability of the new device is demonstrated on the liquid crystal 4'-octyl-4-cyano-biphenyl (8CB) in its smectic A (SmA) mesophase. Its molecular-scale structure and orientation confined in 100 nm to 1.7 μm slit pores was studied under static and dynamic nonequilibrium conditions.
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Affiliation(s)
- Henning Weiss
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Hsiu-Wei Cheng
- Institute
of Applied Physics, Vienna Institute of
Technology, Wiedner Hauptstrasse 8-10/E134, 1040 Wien, Austria
| | - Julian Mars
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Institute
of Physics, Johannes Gutenberg University
Mainz, 55128 Mainz, Germany
| | - Hailong Li
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Claudia Merola
- Institute
of Applied Physics, Vienna Institute of
Technology, Wiedner Hauptstrasse 8-10/E134, 1040 Wien, Austria
| | - Frank Uwe Renner
- Institute
for Materials Research, Hasselt University, 3590 Diepenbeek, Belgium
| | - Veijo Honkimäki
- ESRF-European
Synchrotron Radiation Facility, Avenue des Martyrs 71, 38043 Grenoble, Cedex 9, France
| | - Markus Valtiner
- Institute
of Applied Physics, Vienna Institute of
Technology, Wiedner Hauptstrasse 8-10/E134, 1040 Wien, Austria
- Max-Planck-Institut
für Eisenforschung GmbH, Max-Planck-Strasse 1, 40237 Düsseldorf, Germany
| | - Markus Mezger
- Max
Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
- Institute
of Physics, Johannes Gutenberg University
Mainz, 55128 Mainz, Germany
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20
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Gurkan B, Squire H, Pentzer E. Metal-Free Deep Eutectic Solvents: Preparation, Physical Properties, and Significance. J Phys Chem Lett 2019; 10:7956-7964. [PMID: 31804088 DOI: 10.1021/acs.jpclett.9b01980] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In the past decade, reports detailing the preparation, characterization, and application of deep eutectic solvents (DESs) have grown in number significantly, showing signs of increased interest and attention. Indeed, these systems provide tunable polar environments attractive for their ease of synthesis and lack of need for purification. DESs are homogeneous systems composed of two or more components having a significantly depressed melting point compared to either constituent material. As interest and application of DESs grow, the need for a common understanding of their preparation and characterization is required. In this Perspective, we discuss metal-free DESs, focusing on their preparation, characterization of physical properties, and considerations for their application. We highlight inconsistencies or omissions in literature reports as well as factors for researchers to consider when investigating these systems.
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Affiliation(s)
- Burcu Gurkan
- Chemical and Biomolecular Engineering Department , Case Western Reserve University , Cleveland , Ohio 44106 , United States
| | - Henry Squire
- Chemical and Biomolecular Engineering Department , Case Western Reserve University , Cleveland , Ohio 44106 , United States
| | - Emily Pentzer
- Department of Chemistry, Department of Materials Science and Engineering , Texas A&M University , College Station , Texas 77807 , United States
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21
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Delcea M, Helm CA. X-ray and Neutron Reflectometry of Thin Films at Liquid Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:8519-8530. [PMID: 30901219 DOI: 10.1021/acs.langmuir.8b04315] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In the 1980s, Helmuth Möhwald studied lipid monolayers at the air/water interface to understand the thermodynamically characterized phases at the molecular level. In collaboration with Jens Als-Nielsen, X-ray reflectometry was used and further developed to determine the electron density profile perpendicular to the water surface. Using a slab model, parameters such as thickness and density of the individual molecular regions, as well as the roughness of the individual interfaces, were determined. Later, X-ray and neutron reflectometry helped to understand the coverage and conformation of anchored and adsorbed polymers. Nowadays, they resolve molecular properties in emerging topics such as liquid metals and ionic liquids. Much is still to be learned about buried interfaces (e.g., liquid/liquid interfaces). In this Article, a historical and theoretical background of X-ray reflectivity is given, recent developments of X-ray and neutron reflectometry for polymers at interfaces and thin layers are highlighted, and emerging research topics involving these techniques are emphasized.
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Affiliation(s)
- Mihaela Delcea
- Institute of Biochemistry , University of Greifswald , Felix-Hausdorff-Straße 4 , 17489 Greifswald , Germany
- ZIK HIKE- Zentrum für Innovationskompetenz , Humorale Immunreaktionen bei kardiovaskulären Erkrankungen , Fleischmannstraße 42 , 17489 Greifswald , Germany
| | - Christiane A Helm
- Institute of Physics , University of Greifswald , Felix-Hausdorff-Straße 4 , 17489 Greifswald , Germany
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22
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Curry JN, Shaw SK. Thermotropic Phase Transitions in Butyltrimethylammonium Bis(trifluoromethylsulfonyl)imide Ionic Liquids are Dependent on Heat Flux. J Phys Chem B 2019; 123:4757-4765. [DOI: 10.1021/acs.jpcb.9b01650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jaclyn N. Curry
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52245, United States
| | - Scott K. Shaw
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52245, United States
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23
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Wei Q, Zhang M, Zhou D, Li X, Bian H, Fang Y. Ultrafast Hydrogen Bond Exchanging between Water and Anions in Concentrated Ionic Liquid Aqueous Solutions. J Phys Chem B 2019; 123:4766-4775. [PMID: 31082232 DOI: 10.1021/acs.jpcb.9b03504] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mixtures of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) ionic liquids (ILs) and water as a function of IL concentrations have been investigated by Fourier transform infrared (FTIR) spectroscopy and ultrafast two-dimensional IR (2D IR) spectroscopy. FTIR spectra of the mixtures resolve two different types of water species, one interacting with the BF4- anions and the other associated with bulklike water molecules. These two water species are in a dynamic equilibrium through forming different hydrogen bonding configurations which are separated by more than 100 cm-1 in the IR spectra. The structural dynamics of the IL mixtures are further revealed by monitoring the vibrational relaxation dynamics of the OD stretching group of interfacial water molecules hydrogen bonded to BF4- anions. With the increase of the IL bulk concentration, vibrational population and rotational dynamics of the interfacial water molecules can be described by a biexponential decay function and are strongly dependent on the IL concentrations. Furthermore, the ultrafast hydrogen bond exchanging between water and BF4- anions in the ILs are also measured using 2D IR spectroscopy. The average hydrogen bond exchanging rate is determined to be 19 ± 4 ps, which is around 3 times slower than that in the NaBF4 electrolyte aqueous solution. The much slower hydrogen bond exchanging rate indicates that the local structure of ILs and water molecules are strongly mediated by the steric effect of the cationic group in the ILs, which is proposed to be responsible for the formation of the heterogeneous structure in the IL mixtures. By using SCN- as the anionic probe, the structural inhomogeneity in the IL solutions can be confirmed from the distinct rotational dynamics of the SCN-, which is segregated from the rotational dynamics of water molecules in the IL mixtures.
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Affiliation(s)
- Qianshun Wei
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an 710119 , China
| | - Miaomiao Zhang
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an 710119 , China
| | - Dexia Zhou
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an 710119 , China
| | - Xiaoqian Li
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an 710119 , China
| | - Hongtao Bian
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an 710119 , China
| | - Yu Fang
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an 710119 , China
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24
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Harlow GS, Aldous IM, Thompson P, Gründer Y, Hardwick LJ, Lucas CA. Adsorption, surface relaxation and electrolyte structure at Pt(111) electrodes in non-aqueous and aqueous acetonitrile electrolytes. Phys Chem Chem Phys 2019; 21:8654-8662. [DOI: 10.1039/c9cp00499h] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Application of synchrotron X-ray scattering to probe the atomic structure of the interface between Pt(111) electrodes and non-aqueous acetonitrile electrolytes.
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Affiliation(s)
- Gary S. Harlow
- Oliver Lodge Laboratory
- Department of Physics
- University of Liverpool
- Liverpool
- UK
| | - Iain M. Aldous
- Department of Chemistry
- University of Liverpool
- Liverpool
- UK
| | - Paul Thompson
- Oliver Lodge Laboratory
- Department of Physics
- University of Liverpool
- Liverpool
- UK
| | - Yvonne Gründer
- Oliver Lodge Laboratory
- Department of Physics
- University of Liverpool
- Liverpool
- UK
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25
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Klein JM, Panichi E, Gurkan B. Potential dependent capacitance of [EMIM][TFSI], [N1114][TFSI] and [PYR13][TFSI] ionic liquids on glassy carbon. Phys Chem Chem Phys 2019; 21:3712-3720. [DOI: 10.1039/c8cp04631j] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Potential dependent capacitance of [N1114][TFSI] suggests the crowding mechanism at the wings of the potential range and overscreening near PZC.
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Affiliation(s)
- Jeffrey M. Klein
- Department of Chemical and Biomolecular Engineering
- Case Western Reserve University
- Cleveland
- USA
| | - Evio Panichi
- Department of Chemical and Biomolecular Engineering
- Case Western Reserve University
- Cleveland
- USA
| | - Burcu Gurkan
- Department of Chemical and Biomolecular Engineering
- Case Western Reserve University
- Cleveland
- USA
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26
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Song Y, Huo F, Jiang Y, Zhang S, Chen S. In Situ Tracking of Organic Reactions at the Vapor/Liquid Interfaces of Ionic Liquids. Chemphyschem 2018; 19:2741-2750. [PMID: 30003635 DOI: 10.1002/cphc.201800476] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Indexed: 11/07/2022]
Abstract
The molecular structures of ionic liquids at interfaces play a crucial role in determining their chemical activities in applications. In situ X-ray photoelectron spectroscopy (XPS) was used to track the evolution of X-ray irradiation-induced chemical reactions in a series of ionic liquids ([Cn mim][AuCl4 ]; n=4, 6, 8, 10) on the Si (111) single-crystal surface. Analyses of microstructure and chemical bonding based on the XPS results indicated that reactions occurred at the vapor/liquid interfaces of the ionic liquids. The time-resolved XPS spectra revealed that with increasing irradiation time, the intensity of the peak corresponding to trivalent Au anion decreased for the four ionic liquids as Au was continually reduced to a lower chemical state and finally converted to gold nanoparticles. The rate and conversion of the reaction were associated with the length of the alkyl chain of the ionic liquids cation. Molecular dynamics simulations further revealed that the alkyl chain of the cation in the ionic liquids was oriented towards the vacuum environment at the vapor/liquid interface. Our results provide a real-time atomic-scale experimental evidence of organic reactions at the vapor/liquid interfaces of ionic liquids. The findings are important for understanding the roles of ionic liquids in catalysis, separation, electrochemistry, functional materials, and so on.
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Affiliation(s)
- Yuting Song
- Beijing Key Laboratory of Ionic Liquids Clean Process, Key Laboratory of Green Process and Engineering State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China.,Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu, 610041, China.,University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Feng Huo
- Beijing Key Laboratory of Ionic Liquids Clean Process, Key Laboratory of Green Process and Engineering State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China
| | - Yi Jiang
- Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu, 610041, China
| | - Suojiang Zhang
- Beijing Key Laboratory of Ionic Liquids Clean Process, Key Laboratory of Green Process and Engineering State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China
| | - Shimou Chen
- Beijing Key Laboratory of Ionic Liquids Clean Process, Key Laboratory of Green Process and Engineering State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, China
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27
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Pilkington GA, Harris K, Bergendal E, Reddy AB, Palsson GK, Vorobiev A, Antzutkin ON, Glavatskih S, Rutland MW. Electro-responsivity of ionic liquid boundary layers in a polar solvent revealed by neutron reflectance. J Chem Phys 2018; 148:193806. [DOI: 10.1063/1.5001551] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Affiliation(s)
- Georgia A. Pilkington
- Surface and Corrosion Science, Department of Chemistry, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Kathryn Harris
- System and Component Design, Department of Machine Design, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Erik Bergendal
- Surface and Corrosion Science, Department of Chemistry, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Akepati Bhaskar Reddy
- System and Component Design, Department of Machine Design, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Gunnar K. Palsson
- Department of Physics and Astronomy, Division of Materials Physics, Uppsala University, Uppsala, Sweden
| | - Alexei Vorobiev
- Department of Physics and Astronomy, Division of Materials Physics, Uppsala University, Uppsala, Sweden
| | | | - Sergei Glavatskih
- System and Component Design, Department of Machine Design, KTH Royal Institute of Technology, Stockholm, Sweden
- Department of Electrical Energy, Systems and Automation, Ghent University, Ghent, Belgium
| | - Mark W. Rutland
- Surface and Corrosion Science, Department of Chemistry, KTH Royal Institute of Technology, Stockholm, Sweden
- Surfaces, Processes and Formulation, RISE Research Institutes of Sweden, Stockholm, Sweden
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28
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Abe H, Murata K, Kiyokawa S, Yoshimura Y. Surface tension anomalies in room temperature ionic liquids-acetone solutions. Chem Phys Lett 2018. [DOI: 10.1016/j.cplett.2018.03.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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29
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Cheng HW, Weiss H, Stock P, Chen YJ, Reinecke CR, Dienemann JN, Mezger M, Valtiner M. Effect of Concentration on the Interfacial and Bulk Structure of Ionic Liquids in Aqueous Solution. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:2637-2646. [PMID: 29356544 DOI: 10.1021/acs.langmuir.7b03757] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Bio and aqueous applications of ionic liquids (IL) such as catalysis in micelles formed in aqueous IL solutions or extraction of chemicals from biologic materials rely on surface-active and self-assembly properties of ILs. Here, we discuss qualitative relations of the interfacial and bulk structuring of a water-soluble surface-active IL ([C8MIm][Cl]) on chemically controlled surfaces over a wide range of water concentrations using both force probe and X-ray scattering experiments. Our data indicate that IL structuring evolves from surfactant-like surface adsorption at low IL concentrations, to micellar bulk structure adsorption above the critical micelle concentration, to planar bilayer formation in ILs with <1 wt % of water and at high charging of the surface. Interfacial structuring is controlled by mesoscopic bulk structuring at high water concentrations. Surface chemistry and surface charges decisively steer interfacial ordering of ions if the water concentration is low and/or the surface charge is high. We also demonstrate that controlling the interfacial forces by using self-assembled monolayer chemistry allows tuning of interfacial structures. Both the ratio of the head group size to the hydrophobic tail volume as well as the surface charging trigger the bulk structure and offer a tool for predicting interfacial structures. Based on the applied techniques and analyses, a qualitative prediction of molecular layering of ILs in aqueous systems is possible.
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Affiliation(s)
- H-W Cheng
- Department for Interface Chemistry and Surface Engineering, Max Planck Institut für Eisenforschung GmbH , 40237 Düsseldorf, Germany
- Institute of Applied Physics, Vienna University of Technology , A-1040 Vienna, Austria
| | - H Weiss
- Max Planck Institute for Polymer Research , 55128 Mainz, Germany
| | - P Stock
- Department for Interface Chemistry and Surface Engineering, Max Planck Institut für Eisenforschung GmbH , 40237 Düsseldorf, Germany
| | - Y-J Chen
- Department for Interface Chemistry and Surface Engineering, Max Planck Institut für Eisenforschung GmbH , 40237 Düsseldorf, Germany
| | - C R Reinecke
- Department for Interface Chemistry and Surface Engineering, Max Planck Institut für Eisenforschung GmbH , 40237 Düsseldorf, Germany
| | - J-N Dienemann
- Department for Interface Chemistry and Surface Engineering, Max Planck Institut für Eisenforschung GmbH , 40237 Düsseldorf, Germany
| | - M Mezger
- Max Planck Institute for Polymer Research , 55128 Mainz, Germany
- Institute of Physics, Johannes Gutenberg University Mainz , 55128 Mainz, Germany
| | - M Valtiner
- Department for Interface Chemistry and Surface Engineering, Max Planck Institut für Eisenforschung GmbH , 40237 Düsseldorf, Germany
- Institute of Applied Physics, Vienna University of Technology , A-1040 Vienna, Austria
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30
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Haddad J, Pontoni D, Murphy BM, Festersen S, Runge B, Magnussen OM, Steinrück HG, Reichert H, Ocko BM, Deutsch M. Surface structure evolution in a homologous series of ionic liquids. Proc Natl Acad Sci U S A 2018; 115:E1100-E1107. [PMID: 29358372 PMCID: PMC5819424 DOI: 10.1073/pnas.1716418115] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Interfaces of room temperature ionic liquids (RTILs) are important for both applications and basic science and are therefore intensely studied. However, the evolution of their interface structure with the cation's alkyl chain length [Formula: see text] from Coulomb to van der Waals interaction domination has not yet been studied for even a single broad homologous RTIL series. We present here such a study of the liquid-air interface for [Formula: see text], using angstrom-resolution X-ray methods. For [Formula: see text], a typical "simple liquid" monotonic surface-normal electron density profile [Formula: see text] is obtained, like those of water and organic solvents. For [Formula: see text], increasingly more pronounced nanoscale self-segregation of the molecules' charged moieties and apolar chains yields surface layering with alternating regions of headgroups and chains. The layering decays into the bulk over a few, to a few tens, of nanometers. The layering periods and decay lengths, their linear [Formula: see text] dependence, and slopes are discussed within two models, one with partial-chain interdigitation and the other with liquid-like chains. No surface-parallel long-range order is found within the surface layer. For [Formula: see text], a different surface phase is observed above melting. Our results also impact general liquid-phase issues like supramolecular self-aggregation and bulk-surface structure relations.
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Affiliation(s)
- Julia Haddad
- Physics Department, Bar-Ilan University, Ramat Gan 5290002, Israel
- Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Diego Pontoni
- European Synchrotron Radiation Facility, The European Synchrotron and Partnership for Soft Condensed Matter (PSCM), 38000 Grenoble, France
| | - Bridget M Murphy
- Institute for Experimental and Applied Physics, Kiel University, 24118 Kiel, Germany
- Ruprecht Haensel Laboratory, Kiel University, 24098 Kiel, Germany
| | - Sven Festersen
- Institute for Experimental and Applied Physics, Kiel University, 24118 Kiel, Germany
| | - Benjamin Runge
- Institute for Experimental and Applied Physics, Kiel University, 24118 Kiel, Germany
| | - Olaf M Magnussen
- Institute for Experimental and Applied Physics, Kiel University, 24118 Kiel, Germany
- Ruprecht Haensel Laboratory, Kiel University, 24098 Kiel, Germany
| | - Hans-Georg Steinrück
- Stanford Synchrotron Radiation Laboratory (SSRL) Materials Science Division, Stanford Linear Accelerator Center (SLAC) National Accelerator Laboratory, Menlo Park, CA 94025
| | - Harald Reichert
- European Synchrotron Radiation Facility, The European Synchrotron, 38000 Grenoble, France
| | - Benjamin M Ocko
- National Synchrotron Light Source II (NSLS-II), Brookhaven National Laboratory, Upton, NY 11973
| | - Moshe Deutsch
- Physics Department, Bar-Ilan University, Ramat Gan 5290002, Israel;
- Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat Gan 5290002, Israel
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31
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Mars J, Hou B, Weiss H, Li H, Konovalov O, Festersen S, Murphy BM, Rütt U, Bier M, Mezger M. Surface induced smectic order in ionic liquids - an X-ray reflectivity study of [C 22C 1im] +[NTf 2] . Phys Chem Chem Phys 2018; 19:26651-26661. [PMID: 28960006 DOI: 10.1039/c7cp04852a] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Surface induced smectic order was found for the ionic liquid 1-methyl-3-docosylimidazolium bis(trifluoromethlysulfonyl)imide by X-ray reflectivity and grazing incidence scattering experiments. Near the free liquid surface, an ordered structure of alternating layers composed of polar and non-polar moieties is observed. This leads to an oscillatory interfacial profile perpendicular to the liquid surface with a periodicity of 3.7 nm. Small angle X-ray scattering and polarized light microscopy measurements suggest that the observed surface structure is related to fluctuations into a metastable liquid crystalline SmA2 phase that was found by supercooling the bulk liquid. The observed surface ordering persists up to 157 °C, i.e. more than 88 K above the bulk melting temperature of 68.1 °C. Close to the bulk melting point, we find a thickness of the ordered layer of L = 30 nm. The dependency of L(τ) = Λ ln(τ/τ1) vs. reduced temperature τ follows a logarithmic growth law. In agreement with theory, the pre-factor Λ is governed by the correlation length of the isotropic bulk phase.
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Affiliation(s)
- Julian Mars
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
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32
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Beniwal V, Kumar A. Thermodynamic and molecular origin of interfacial rate enhancements and endo-selectivities of a Diels-Alder reaction. Phys Chem Chem Phys 2018; 19:4297-4306. [PMID: 28116364 DOI: 10.1039/c6cp07405g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Organic reactions in general display large rate accelerations when performed under interfacial conditions, such as on water or at ionic liquid interfaces. However, a clear picture of the physicochemical factors responsible for this large rate enhancements is not available. To gain an understanding of the thermodynamic and molecular origin of these large rate enhancements, we performed a Diels-Alder reaction between cyclopentadiene and methyl acrylate at ionic liquid/n-hexane interfaces. This study describes, for the first time, a methodology for the calculation of the activation parameters of an interfacial reaction. It has been seen that the energy of activation for an interfacial reaction is much smaller than that of the corresponding homogeneous reaction, resulting into the large rate acceleration for the interfacial reaction. Furthermore, the study describes the effects of the alkyl chain length of ionic liquid cations, the extent of heterogeneity, and the polarity of ionic liquids on the rate constants and stereoselectivity of the reaction.
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Affiliation(s)
- Vijay Beniwal
- Physical & Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India.
| | - Anil Kumar
- Physical & Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India.
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33
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Camci MT, Aydogan P, Ulgut B, Kocabas C, Suzer S. XPS enables visualization of electrode potential screening in an ionic liquid medium with temporal- and lateral-resolution. Phys Chem Chem Phys 2018; 18:28434-28440. [PMID: 27757457 DOI: 10.1039/c6cp04933h] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present an X-ray photoelectron spectroscopic (XPS) investigation of potential screening across two gold electrodes fabricated on a porous polymer surface which is impregnated with the ionic liquid (IL) N-N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide [DEME-TFSI]. The IL provides a sheet of conducting layers to the insulating polymer film, and allows monitoring charging and screening dynamics at the polymer + IL/vacuum interface in a laterally resolved fashion across the electrodes. Time-resolved measurements are also implemented by recording F1s peaks of the IL, while imposing 10 mHz square-wave (SQW) pulses across the two electrodes in a source-drain geometry. Variations in the F1s binding energy reflect directly the transient local electrical potential, and allow us to visualize screening of the otherwise built-in local voltage drop on and across the metal electrodes in the range of millimeters. Accordingly, the device is partitioned into two oppositely polarized regions, each following polarization of one electrode through the IL medium. On the other extreme, upon imposing relatively fast 1 kHz SQW pulses the charge screening is prevented and the device is brought to assume a simple resistor role. A simple equivalent circuit model also reproduces the observed voltage transients qualitatively. The presented structure and variants of XPS measurements, enabling us to record voltage transients in unexpectedly large lateral distances away from the electrodes, can impact the understanding of various electrochemical concepts.
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Affiliation(s)
- M T Camci
- Department of Chemistry, Bilkent University, Ankara 06800, Turkey.
| | - P Aydogan
- Department of Chemistry, Bilkent University, Ankara 06800, Turkey.
| | - B Ulgut
- Department of Chemistry, Bilkent University, Ankara 06800, Turkey.
| | - C Kocabas
- Department of Physics, Bilkent University, Ankara 06800, Turkey
| | - S Suzer
- Department of Chemistry, Bilkent University, Ankara 06800, Turkey.
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34
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Luo X, Deng S, Wang P. Temporal–spatial-resolved mapping of the electrical double layer changes by surface plasmon resonance imaging. RSC Adv 2018; 8:28266-28274. [PMID: 35542477 PMCID: PMC9084293 DOI: 10.1039/c8ra05380d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Accepted: 07/30/2018] [Indexed: 11/21/2022] Open
Abstract
An electrical double layer (EDL) is a specific distribution of ions at the electrolyte/electrode interface. As EDL plays a decisive role in the interfacial physical and chemical characteristics, a comprehensive and quantitative understanding of the EDL structure and its change dynamics is important for a wide range of fields, ranging from electrochemistry, energy storage and semiconductor materials to biotechnology. In this paper, we proposed a proof of concept method for temporal- and spatial-resolved mapping of the EDL structure and its change dynamics. A potential was applied on the interface and the potential induced ion re-arrangement process was monitored by surface plasmon resonance (SPR) imaging in real time. NaCl experiments were repeated six times and the coefficient of variation of the results was 5.17%, confirming the potential-induced SPR response. Experiments with different potential excitations, ion concentrations and species were performed and results indicated that the electron density change and ion re-arrangement contributed comparably to the potential induced SPR response. Additionally, the lateral distribution of the EDL formed at the interface between NaCl solutions and an Au film coated with arrays of 11-MUA spots was mapped. This method is temporally and spatially resolved, and thus has the potential to be a promising tool for EDL studies at heterogeneous interfaces. This paper provides a novel method for temporal–spatial-resolved mapping of the electrical double layer changes at the heterogeneous interface.![]()
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Affiliation(s)
- Xueyi Luo
- State Key Laboratory of Precision Measurement Technology and Instruments
- Department of Precision Instrument
- Tsinghua University
- Beijing 100084
- PR China
| | - Shijie Deng
- State Key Laboratory of Precision Measurement Technology and Instruments
- Department of Precision Instrument
- Tsinghua University
- Beijing 100084
- PR China
| | - Peng Wang
- State Key Laboratory of Precision Measurement Technology and Instruments
- Department of Precision Instrument
- Tsinghua University
- Beijing 100084
- PR China
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35
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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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36
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Sedghamiz E, Moosavi M. Probing the tricationic ionic liquid/vacuum interface: insights from molecular dynamics simulations. Phys Chem Chem Phys 2018; 20:14251-14263. [DOI: 10.1039/c8cp02471e] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The surface properties of three symmetric linear tricationic ionic liquids (LTILs) with the common anion, bis(trifluoromethylsulfonyl)imide ([NTf2]−), were studied using atomistic molecular dynamics simulation and identification of the truly interfacial molecules (ITIM) analysis.
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Affiliation(s)
- Elaheh Sedghamiz
- Department of Chemistry
- University of Isfahan
- Isfahan 81746-73441
- Iran
| | - Majid Moosavi
- Department of Chemistry
- University of Isfahan
- Isfahan 81746-73441
- Iran
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37
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Filippov A, Gnezdilov OI, Hjalmarsson N, Antzutkin ON, Glavatskih S, Furó I, Rutland MW. Acceleration of diffusion in ethylammonium nitrate ionic liquid confined between parallel glass plates. Phys Chem Chem Phys 2017; 19:25853-25858. [PMID: 28932828 DOI: 10.1039/c7cp01772c] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Diffusion of EAN confined between polar glass plates separated by a few micrometers is higher by a factor of ca. 2 as compared to bulk values. Formation of a new phase, different to the bulk, was suggested.
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Affiliation(s)
- Andrei Filippov
- Chemistry of Interfaces, Luleå University of Technology, SE-97187 Luleå, Sweden. and Institute of Physics, Kazan Federal University, 420008 Kazan, Russia
| | - Oleg I Gnezdilov
- Institute of Physics, Kazan Federal University, 420008 Kazan, Russia
| | - Nicklas Hjalmarsson
- Surface and Corrosion Science, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - Oleg N Antzutkin
- Chemistry of Interfaces, Luleå University of Technology, SE-97187 Luleå, Sweden.
| | - Sergei Glavatskih
- System and Component Design, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden and Department of Mechanical Construction and Production, Ghent University, B-9000 Ghent, Belgium
| | - István Furó
- Applied Physical Chemistry, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - Mark W Rutland
- Surface and Corrosion Science, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden and RISE Technical Research Institute of Sweden, Chemistry Materials and Surfaces, Box 5607, SE-11486 Stockholm, Sweden
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38
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Afandak A, Eslami H. Ion-Pairing and Electrical Conductivity in the Ionic Liquid 1-n-Butyl-3-methylimidazolium Methylsulfate [Bmim][MeSO4]: Molecular Dynamics Simulation Study. J Phys Chem B 2017; 121:7699-7708. [DOI: 10.1021/acs.jpcb.7b06039] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Azam Afandak
- Department of Chemistry, College
of Sciences, Persian Gulf University, Boushehr 75168, Iran
| | - Hossein Eslami
- Department of Chemistry, College
of Sciences, Persian Gulf University, Boushehr 75168, Iran
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39
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Zheng W, Xie W, Sun W, Zhao L. Modeling of the interfacial behaviors for the isobutane alkylation with C4 olefin using ionic liquid as catalyst. Chem Eng Sci 2017. [DOI: 10.1016/j.ces.2017.02.049] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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40
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Affiliation(s)
- Kun Dong
- State Key Laboratory of Multiphase
Complex Systems, Beijing Key Laboratory of Ionic Liquids Clean Process,
Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiaomin Liu
- State Key Laboratory of Multiphase
Complex Systems, Beijing Key Laboratory of Ionic Liquids Clean Process,
Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Haifeng Dong
- State Key Laboratory of Multiphase
Complex Systems, Beijing Key Laboratory of Ionic Liquids Clean Process,
Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiangping Zhang
- State Key Laboratory of Multiphase
Complex Systems, Beijing Key Laboratory of Ionic Liquids Clean Process,
Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Suojiang Zhang
- State Key Laboratory of Multiphase
Complex Systems, Beijing Key Laboratory of Ionic Liquids Clean Process,
Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
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41
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Physicochemical and thermodynamic properties of imidazolium ionic liquids with nitrile and ether dual functional groups. J Mol Liq 2017. [DOI: 10.1016/j.molliq.2016.11.049] [Citation(s) in RCA: 19] [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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42
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Purcell SM, Tesa-Serrate MA, Marshall BC, Bruce DW, D'Andrea L, Costen ML, Slattery JM, Smoll EJ, Minton TK, McKendrick KG. Reactive-Atom Scattering from Liquid Crystals at the Liquid-Vacuum Interface: [C 12mim][BF 4] and 4-Cyano-4'-Octylbiphenyl (8CB). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:9938-9949. [PMID: 27603521 DOI: 10.1021/acs.langmuir.6b02440] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Two complementary approaches were used to study the liquid-vacuum interface of the liquid-crystalline ionic liquid 1-dodecyl-3-methylimidazolium tetrafluoroborate ([C12mim][BF4]) in the smectic A (SmA) and isotropic phases. O atoms with two distinct incident translational energies were scattered from the surface of [C12mim][BF4]. Angle-dependent time-of-flight distributions and OH yields, respectively, were recorded from high- and low-energy O atoms. There were no significant changes in the measurements using either approach, nor the properties derived from them, accompanying the transition from the SmA to the isotropic phase. This indicates that the surface structure of [C12mim][BF4] remains essentially unchanged across the phase boundary, implying that the bulk order and surface structure are not strongly correlated for this material. This effect is ascribed to the strong propensity for the outer surfaces of ionic liquids to be dominated by alkyl chains, over an underlying layer rich in anions and cation head groups, whether or not the bulk material is a liquid crystal. In a comparative study, the OH yield from the surface of the liquid crystal, 8CB, was found to be affected by the bulk order, showing a surprising step increase at the SmA-nematic transition temperature, whose origin is the subject of speculation.
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Affiliation(s)
- Simon M Purcell
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, United Kingdom
| | - Maria A Tesa-Serrate
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, United Kingdom
| | - Brooks C Marshall
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Duncan W Bruce
- Department of Chemistry, University of York , Heslington, York YO10 5DD, United Kingdom
| | - Lucía D'Andrea
- Department of Chemistry, University of York , Heslington, York YO10 5DD, United Kingdom
| | - Matthew L Costen
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, United Kingdom
| | - John M Slattery
- Department of Chemistry, University of York , Heslington, York YO10 5DD, United Kingdom
| | - Eric J Smoll
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Timothy K Minton
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Kenneth G McKendrick
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University , Edinburgh EH14 4AS, United Kingdom
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43
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Png RQ, Ang MC, Teo MH, Choo KK, Tang CG, Belaineh D, Chua LL, Ho PK. Madelung and Hubbard interactions in polaron band model of doped organic semiconductors. Nat Commun 2016; 7:11948. [PMID: 27582355 PMCID: PMC5025745 DOI: 10.1038/ncomms11948] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 05/17/2016] [Indexed: 11/09/2022] Open
Abstract
The standard polaron band model of doped organic semiconductors predicts that density-of-states shift into the π-π* gap to give a partially filled polaron band that pins the Fermi level. This picture neglects both Madelung and Hubbard interactions. Here we show using ultrahigh workfunction hole-doped model triarylamine-fluorene copolymers that Hubbard interaction strongly splits the singly-occupied molecular orbital from its empty counterpart, while Madelung (Coulomb) interactions with counter-anions and other carriers markedly shift energies of the frontier orbitals. These interactions lower the singly-occupied molecular orbital band below the valence band edge and give rise to an empty low-lying counterpart band. The Fermi level, and hence workfunction, is determined by conjunction of the bottom edge of this empty band and the top edge of the valence band. Calculations are consistent with the observed Fermi-level downshift with counter-anion size and the observed dependence of workfunction on doping level in the strongly doped regime.
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Affiliation(s)
- Rui-Qi Png
- Department of Physics, National University of Singapore, Lower Kent Ridge Road, Singapore S117550, Singapore
- Solar Energy Research Institute of Singapore (SERIS), National University of Singapore, 7 Engineering Drive 1, Singapore S117574, Singapore
| | - Mervin C.Y. Ang
- Solar Energy Research Institute of Singapore (SERIS), National University of Singapore, 7 Engineering Drive 1, Singapore S117574, Singapore
- Department of Chemistry, National University of Singapore, Lower Kent Ridge Road, Singapore S117552, Singapore
| | - Meng-How Teo
- Department of Physics, National University of Singapore, Lower Kent Ridge Road, Singapore S117550, Singapore
| | - Kim-Kian Choo
- Department of Chemistry, National University of Singapore, Lower Kent Ridge Road, Singapore S117552, Singapore
| | - Cindy Guanyu Tang
- Department of Physics, National University of Singapore, Lower Kent Ridge Road, Singapore S117550, Singapore
- Solar Energy Research Institute of Singapore (SERIS), National University of Singapore, 7 Engineering Drive 1, Singapore S117574, Singapore
| | - Dagmawi Belaineh
- Department of Physics, National University of Singapore, Lower Kent Ridge Road, Singapore S117550, Singapore
| | - Lay-Lay Chua
- Department of Physics, National University of Singapore, Lower Kent Ridge Road, Singapore S117550, Singapore
- Solar Energy Research Institute of Singapore (SERIS), National University of Singapore, 7 Engineering Drive 1, Singapore S117574, Singapore
- Department of Chemistry, National University of Singapore, Lower Kent Ridge Road, Singapore S117552, Singapore
| | - Peter K.H. Ho
- Department of Physics, National University of Singapore, Lower Kent Ridge Road, Singapore S117550, Singapore
- Solar Energy Research Institute of Singapore (SERIS), National University of Singapore, 7 Engineering Drive 1, Singapore S117574, Singapore
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44
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Nakajima K, Nakanishi S, Lísal M, Kimura K. Surface structure of imidazolium-based ionic liquids: Quantitative comparison between simulations and high-resolution RBS measurements. J Chem Phys 2016; 144:114702. [PMID: 27004888 DOI: 10.1063/1.4943887] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Elemental depth profiles of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([CnMIM][TFSI], n = 4, 6, 8) are measured using high-resolution Rutherford backscattering spectroscopy (HRBS). The profiles are compared with the results of molecular dynamics (MD) simulations. Both MD simulations and HRBS measurements show that the depth profiles deviate from the uniform stoichiometric composition in the surface region, showing preferential orientations of ions at the surface. The MD simulations qualitatively reproduce the observed HRBS profiles but the agreement is not satisfactory. The observed discrepancy is ascribed to the capillary waves. By taking account of the surface roughness induced by the capillary waves, the agreement becomes almost perfect.
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Affiliation(s)
- Kaoru Nakajima
- Department of Micro Engineering, Kyoto University, Kyoto-daigaku-katsura, Nishikyo, Kyoto 615-8540, Japan
| | - Shunto Nakanishi
- Department of Micro Engineering, Kyoto University, Kyoto-daigaku-katsura, Nishikyo, Kyoto 615-8540, Japan
| | - Martin Lísal
- Laboratory of Aerosols Chemistry and Physics, Institute of Chemical Process Fundamentals of the CAS, v. v. i., Suchdol, Prague 6 165 02, Czech Republic
| | - Kenji Kimura
- Department of Micro Engineering, Kyoto University, Kyoto-daigaku-katsura, Nishikyo, Kyoto 615-8540, Japan
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45
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Hu YF, Zhang XM, Qi JG, Yin LY. The configuration exchanging theory for transport properties and glass formation temperature of ionic liquids. J Chem Phys 2016; 143:204501. [PMID: 26627962 DOI: 10.1063/1.4936282] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Understanding molecular motion in terms of molecular structure is an important issue for microscopic understanding of the nature of transport properties and glass transition, and for design of structured materials to meet specific demands in various applications. Herein, a novel molecular mechanism is proposed to connect macroscopic motion in ionic liquids with molecular structure via conformational conversions of the constituent ions or of the cation-anion pairs. New equations for description of relaxation time, diffusion coefficient, molar conductivity, and viscosity of ionic liquids are established. The equation parameters, which were determined from the temperature dependent heat capacities, self-diffusion coefficients, molar conductivities, and viscosities of typical ionic liquids, were used to produce predictions for the corresponding properties of other ionic liquids and for the glass transition temperatures of representative ionic liquids. All predictions are in nice agreements with the experimental results.
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Affiliation(s)
- Yu-Feng Hu
- State Key Laboratory of Heavy Oil Processing and High Pressure Fluid Phase Behavior and Property Research Laboratory, China University of Petroleum, Beijing 102249, China
| | - Xian-Ming Zhang
- State Key Laboratory of Heavy Oil Processing and High Pressure Fluid Phase Behavior and Property Research Laboratory, China University of Petroleum, Beijing 102249, China
| | - Jian-Guang Qi
- State Key Laboratory of Heavy Oil Processing and High Pressure Fluid Phase Behavior and Property Research Laboratory, China University of Petroleum, Beijing 102249, China
| | - Liu-Yi Yin
- State Key Laboratory of Heavy Oil Processing and High Pressure Fluid Phase Behavior and Property Research Laboratory, China University of Petroleum, Beijing 102249, China
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46
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Beniwal V, Manna A, Kumar A. Spectacular Rate Enhancement of the Diels-Alder Reaction at the Ionic Liquid/n-Hexane Interface. Chemphyschem 2016; 17:1969-72. [DOI: 10.1002/cphc.201600006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Indexed: 01/09/2023]
Affiliation(s)
- Vijay Beniwal
- Physical and Materials Chemistry Division; CSIR-National Chemical Laboratory; Pune 411008 India
| | - Arpan Manna
- Physical and Materials Chemistry Division; CSIR-National Chemical Laboratory; Pune 411008 India
| | - Anil Kumar
- Physical and Materials Chemistry Division; CSIR-National Chemical Laboratory; Pune 411008 India
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47
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Chu M, Miller M, Dutta P. Crowding and Anomalous Capacitance at an Electrode-Ionic Liquid Interface Observed Using Operando X-ray Scattering. ACS CENTRAL SCIENCE 2016; 2:175-80. [PMID: 27163044 PMCID: PMC4827468 DOI: 10.1021/acscentsci.6b00014] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Indexed: 05/02/2023]
Abstract
Room temperature ionic liquids are widely recognized as novel electrolytes with properties very different from those of aqueous solutions, and thus with many potential applications, but observing how they actually behave at electrolytic interfaces has proved to be challenging. We have studied the voltage-dependent structure of [TDTHP](+)[NTF2](-) near its interface with an electrode, using in situ synchrotron X-ray reflectivity. An anion-rich layer develops at the interface above a threshold voltage of +1.75 V, and the layer thickness increases rapidly with voltage, reaching ∼6 nm (much larger that the anion dimensions) at +2.64 V. These results provide direct confirmation of the theoretical prediction of "crowding" of ions near the interface. The interfacial layer is not purely anionic but a mixture of up to ∼80% anions and the rest cations. The static differential capacitance calculated from X-ray measurements shows an increase at higher voltages, consistent with a recent zero-frequency capacitance measurement but inconsistent with ac capacitance measurements.
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48
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McDonald S, Elbourne A, Warr GG, Atkin R. Metal ion adsorption at the ionic liquid-mica interface. NANOSCALE 2016; 8:906-914. [PMID: 26661934 DOI: 10.1039/c5nr05833c] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Mica has been employed in many studies of ionic liquid (IL) interfaces on account of its atomic smoothness and well defined surface properties. However, until now it has been unclear whether ions dissolved in ILs can compete with the IL cation and adsorb to mica charge sites. In this work amplitude modulated atomic force microscopy (AM-AFM) has been used to probe metal ion adsorption at the interface of mica with propylammonium nitrate (PAN), a room temperature IL. Lithium, sodium, potassium, magnesium and calcium nitrate salts were added to PAN at a concentration of ∼60 mM. Aluminum nitrate was also investigated, but only at 5 mM because its solubility in PAN is much lower. The AM-AFM images obtained when the metal ions were present are strikingly different to that of pure PAN, indicating that the ions compete effectively with the propylammonium cation and adsorb to negatively charged sites on the mica surface despite their much lower concentration. This is a consequence of electrostatic attractions between the mica charge sites and the metal ions being significantly stronger than for the propylammonium cation; compared to the metal ions the propylammonium charged group is relatively constrained sterically. A distinct honeycomb pattern is noted for the PAN + Al(3+) system, less obviously for the divalent ions and not at all for monovalent ions. This difference is attributed to the strength of electrostatic interactions between metal ions and mica charge sites increasing with the ion charge, which means that divalent and (particularly) trivalent ions are located more precisely above the charged sites of the mica lattice. The images obtained allow important distinctions between metal ion adsorption at mica-water and mica-PAN interfaces to be made.
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Affiliation(s)
- Samila McDonald
- Discipline of Chemistry, The Newcastle Institute for Energy and Resources, The University of Newcastle, Newcastle, NSW, Australia.
| | - Aaron Elbourne
- Discipline of Chemistry, The Newcastle Institute for Energy and Resources, The University of Newcastle, Newcastle, NSW, Australia.
| | - Gregory G Warr
- School of Chemistry, University of Sydney, Sydney, NSW, Australia
| | - Rob Atkin
- Discipline of Chemistry, The Newcastle Institute for Energy and Resources, The University of Newcastle, Newcastle, NSW, Australia.
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49
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Singh VK, Shalu S, Chaurasia SK, Singh RK. Development of ionic liquid mediated novel polymer electrolyte membranes for application in Na-ion batteries. RSC Adv 2016. [DOI: 10.1039/c6ra06047a] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Polymer electrolyte membranes based on polymer PEO, ionic liquid, 1-butyl-3-methylimidazolium methylsulfate (BMIM-MS), and salt, sodium methylsulfate (NaMS), were prepared and characterized by SEM, XRD, TGA/DTGA, DSC, ac impedance spectroscopy and cyclic voltammetry.
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Affiliation(s)
- Varun Kumar Singh
- Ionic Liquid & Solid State Ionics Laboratory
- Department of Physics
- Banaras Hindu University
- Varanasi-221005
- India
| | - Shalu Shalu
- Ionic Liquid & Solid State Ionics Laboratory
- Department of Physics
- Banaras Hindu University
- Varanasi-221005
- India
| | - Sujeet Kumar Chaurasia
- Ionic Liquid & Solid State Ionics Laboratory
- Department of Physics
- Banaras Hindu University
- Varanasi-221005
- India
| | - Rajendra Kumar Singh
- Ionic Liquid & Solid State Ionics Laboratory
- Department of Physics
- Banaras Hindu University
- Varanasi-221005
- India
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50
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Misono T, Okada K, Sakai K, Abe M, Sakai H. Surface Adsorption and Micelle Formation of Polyoxyethylene-type Nonionic Surfactants in Mixtures of Water and Hydrophilic Imidazolium-type Ionic Liquid. J Oleo Sci 2016; 65:499-506. [DOI: 10.5650/jos.ess15277] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Takeshi Misono
- Research Institute for Science and Technology, Tokyo University of Science
| | - Kohei Okada
- Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science
| | - Kenichi Sakai
- Research Institute for Science and Technology, Tokyo University of Science
- Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science
| | - Masahiko Abe
- Research Institute for Science and Technology, Tokyo University of Science
| | - Hideki Sakai
- Research Institute for Science and Technology, Tokyo University of Science
- Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science
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