1
|
Kumar A, Andersson GG. A review of ion scattering spectroscopy studies at liquid interfaces with noble gas ion projectiles. Adv Colloid Interface Sci 2024; 333:103302. [PMID: 39340972 DOI: 10.1016/j.cis.2024.103302] [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: 12/21/2023] [Revised: 08/25/2024] [Accepted: 09/09/2024] [Indexed: 09/30/2024]
Abstract
Ion scattering spectroscopy (ISS) is an analytical tool that provides direct structural, topographical, and atomic compositional information at interfaces when ions are used as projectiles. Since its development in 1967, ISS is commonly used to obtain quantitative information about solid interfaces. Over the last couple of decades, ISS has emerged as an important technique to probe liquid interfaces and their studies employing ISS has become not uncommon, more so with Neutral impact collision ion scattering spectroscopy (NICISS). Therefore, here the principle of ISS with a particular focus on NICISS and its data evaluation are summarised while reviewing some important studies at vapor-liquid interfaces that provide direct information for molecular orientation of liquids (including ionic liquids), composition and distribution of atoms (or solutes) and charges as a function of depth to gain vast variety of thermodynamical information. Employing ISS such information can be achieved with high depth resolution of ∼1-2 Å (depending on the nature of the experiment). These examples highlight the significance of ISS and show potential for its application for studies related to specific ion effects, atmospheric reaction in aerosol and sea water droplets, and even determining the fate of environmental pollutants like heavy metal ions and per-fluoroalkyl substances (PFAS). Furthermore, some limitations of ISS are also discussed relating to investigation of high-vapor pressure liquids and probing buried interfaces like liquid-liquid interfaces while presenting progresses made in probing solid-liquid interfaces.
Collapse
Affiliation(s)
- Anand Kumar
- Flinders Institute of Nanoscale Science and Technology, College of Science and Engineering, Flinders University, Adelaide, SA 5042, Australia; CSIRO Environment, Private Bag No. 5, Wembley, WA 6913, Australia
| | - Gunther G Andersson
- Flinders Institute of Nanoscale Science and Technology, College of Science and Engineering, Flinders University, Adelaide, SA 5042, Australia; Flinders Microscopy and Microanalysis, College of Science and Engineering, Flinders University, Adelaide, SA 5042, Australia.
| |
Collapse
|
2
|
Levine DJ, Lee OA, Campbell GM, McBride MK, Kim HJ, Turner KT, Hayward RC, Pikul JH. A Low-Voltage, High-Force Capacity Electroadhesive Clutch Based on Ionoelastomer Heterojunctions. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2304455. [PMID: 37734086 DOI: 10.1002/adma.202304455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 09/18/2023] [Indexed: 09/23/2023]
Abstract
Electroadhesive devices with dielectric films can electrically program changes in stiffness and adhesion, but require hundreds of volts and are subject to failure by dielectric breakdown. Recent work on ionoelastomer heterojunctions has enabled reversible electroadhesion with low voltages, but these materials exhibit limited force capacities and high detachment forces. It is a grand challenge to engineer electroadhesives with large force capacities and programmable detachment at low voltages (<10 V). In this work, tough ionoelastomer/metal mesh composites with low surface energies are synthesized and surface roughness is controlled to realize sub-ten-volt clutches that are small, strong, and easily detachable. Models based on fracture and contact mechanics explain how clutch compliance and surface texture affect force capacity and contact area, which is validated over different geometries and voltages. These ionoelastomer clutches outperform the best existing electroadhesive clutches by fivefold in force capacity per unit area (102 N cm-2 ), with a 40-fold reduction in operating voltage (± 7.5 V). Finally, the ability of the ionoelastomer clutches to resist bending moments in a finger wearable and as a reversible adhesive in an adjustable phone mount is demonstrated.
Collapse
Affiliation(s)
- D J Levine
- Department of Mechanical Engineering & Applied Mechanics, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - O A Lee
- Materials Science and Engineering, University of Colorado, Boulder, CO, 80303, USA
| | - G M Campbell
- Department of Mechanical Engineering & Applied Mechanics, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - M K McBride
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO, 80303, USA
| | - H J Kim
- Department of Chemical and Biomolecular Engineering, Sogang University, Seoul, 04107, South Korea
| | - K T Turner
- Department of Mechanical Engineering & Applied Mechanics, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - R C Hayward
- Materials Science and Engineering, University of Colorado, Boulder, CO, 80303, USA
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO, 80303, USA
| | - J H Pikul
- Department of Mechanical Engineering & Applied Mechanics, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, 53706, USA
| |
Collapse
|
3
|
Zafar A, Evans T, Palgrave RG, ud-Din I. An X-ray photoelectron spectroscopy study of ionic liquids based on a bridged dicationic moiety. JOURNAL OF CHEMICAL RESEARCH 2022. [DOI: 10.1177/17475198221092966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A series of imidazolium and pyridinium-based bridged dicationic ionic liquids have been analysed using X-ray photoelectron spectroscopy. The different electronic environments of the dications have been investigated and a robust fitting model for the carbon C1s region has also been developed. The relative positions of different C1s components and N1s of dications have been determined and their complex C1s photoemission spectra produced from both aromatic and aliphatic carbon states giving photoemission peaks in the binding energy range of 289.0–283.9 eV. A contemporary fitting approach has been applied to a different set of environments which allowing comparison of the binding energies of cationic components of imidazolium and pyridinium-based dicationic ionic liquids. The experimental stoichiometry of all the carbons and nitrogens have also been calculated from XP spectra of the dicationic ionic liquids.
Collapse
Affiliation(s)
- Anham Zafar
- Chemistry Department, University College London, London, UK
- Department of Chemistry, Quaid-i-Azam University, Islamabad, Pakistan
| | - Tim Evans
- Chemistry Department, University College London, London, UK
| | | | - Imtiaz- ud-Din
- Department of Chemistry, Quaid-i-Azam University, Islamabad, Pakistan
| |
Collapse
|
4
|
Morales-Ugarte JE, Santini CC, Bouchet R, Benayad A. New Interpretation of X-ray Photoelectron Spectroscopy of Imidazolium Ionic Liquid Electrolytes Based on Ionic Transport Analyses. J Phys Chem B 2020; 124:7625-7635. [PMID: 32790393 DOI: 10.1021/acs.jpcb.0c04090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We reported a new perspective on the correlation between the electronic structure of an ionic liquid (IL)-based electrolyte probed by X-ray photoelectron spectroscopy and the transport properties analyzed by impedance spectroscopy. We highlighted the core level chemical shifts of 1-hexyl-3-methylimidazolium (bis(trifluoromethanesulfonyl)imide) (C1C6ImTFSI), 1-hexyl-3-methylimidazolium bis(fluorosulfonyl)imide (C1C6ImFSI), and 1-hexyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide (C1C1C6ImTFSI) laden with LiTFSI salt and vinylene carbonate (VC) or fluoroethylene carbonate (FEC) with regard to the transport properties of cations and anions. We pointed out based on detailed binding energy shift analyses a clear effect of the anion on the local organization of Li+ ions. The significant peak shift in the case of C1C6ImTFSI laden with LiTFSI corroborates the formation of [Li(TFSI)2]- complexes. On the contrary, the lower amplitude of the binding energy shift of C1C6ImFSI for both anion- and cation-related peaks indicates that the electronic distribution around the cation and the anion is not affected when the LiTFSI salt is added, which plays a strong role in the ion dynamics (lower viscosity) of the electrolyte. The X-ray photoelectron spectroscopy (XPS) result supports the preponderant role of imidazolium ionic liquid based on FSI anion to form an electrolyte less prone to form ionic complexes. The methylation of the imidazolium cation contributes to the reduction of the interaction between the C1C1C6Im cation and TFSI anion, while additives VC and FEC contribute to the change of the alkyl configuration in C1C6Im cation, leading to the modification of the macroscopic properties of the ILs.
Collapse
Affiliation(s)
- J E Morales-Ugarte
- Université Grenoble Alpes, CEA-LITEN, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France.,Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, Grenoble INP, LEPMI, 1130 rue de La Piscine, 38402 St. Martin d'Hères, France
| | - C C Santini
- Université Lyon, CNRS-UMR 5265, 43 Bd du 11 Novembre 1918, 69616 Villeurbanne, France
| | - R Bouchet
- Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, Grenoble INP, LEPMI, 1130 rue de La Piscine, 38402 St. Martin d'Hères, France
| | - A Benayad
- Université Grenoble Alpes, CEA-LITEN, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France
| |
Collapse
|
5
|
Greco F, Shin S, Williams FJ, Heller BSJ, Maier F, Steinrück H. Potential Screening at Electrode/Ionic Liquid Interfaces from In Situ X-ray Photoelectron Spectroscopy. ChemistryOpen 2019; 8:1365-1368. [PMID: 31844602 PMCID: PMC6892450 DOI: 10.1002/open.201900211] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Indexed: 11/12/2022] Open
Abstract
A new approach to investigate potential screening at the interface of ionic liquids (ILs) and charged electrodes in a two-electrode electrochemical cell by in situ X-ray photoelectron spectroscopy has been introduced. Using identical electrodes, we deduce the potential screening at the working and the counter electrodes as a function of applied voltage from the potential change of the bulk IL, as derived from corresponding core level binding energy shifts for different IL/electrode combinations. For imidazolium-based ILs and Pt electrodes, we find a significantly larger potential screening at the anode than at the cathode, which we attribute to strong attractive interactions between the imidazolium cation and Pt. In the absence of specific ion/electrode interactions, asymmetric potential screening only occurs for ILs with different cation and anion sizes as demonstrated for an imidazolium chloride IL and Au electrodes, which we assign to the different thicknesses of the electrical double layers. Our results imply that potential screening in ILs is mainly established by a single layer of counterions at the electrode.
Collapse
Affiliation(s)
- Francesco Greco
- Lehrstuhl für Physikalische Chemie 2Friedrich-Alexander-Universität Erlangen-NürnbergEgerlandstr. 391058ErlangenGermany
| | - Sunghwan Shin
- Lehrstuhl für Physikalische Chemie 2Friedrich-Alexander-Universität Erlangen-NürnbergEgerlandstr. 391058ErlangenGermany
| | - Federico J. Williams
- Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, INQUIMAE-CONICETUniversidad de Buenos Aires, Ciudad UniversitariaPabellón 2Buenos AiresC1428EHAArgentina
| | - Bettina S. J. Heller
- Lehrstuhl für Physikalische Chemie 2Friedrich-Alexander-Universität Erlangen-NürnbergEgerlandstr. 391058ErlangenGermany
| | - Florian Maier
- Lehrstuhl für Physikalische Chemie 2Friedrich-Alexander-Universität Erlangen-NürnbergEgerlandstr. 391058ErlangenGermany
| | - Hans‐Peter Steinrück
- Lehrstuhl für Physikalische Chemie 2Friedrich-Alexander-Universität Erlangen-NürnbergEgerlandstr. 391058ErlangenGermany
| |
Collapse
|
6
|
Clarke CJ, Maxwell-Hogg S, Smith EF, Hawker RR, Harper JB, Licence P. Resolving X-ray photoelectron spectra of ionic liquids with difference spectroscopy. Phys Chem Chem Phys 2018; 21:114-123. [PMID: 30519695 DOI: 10.1039/c8cp06701e] [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
X-ray photoelectron spectroscopy (XPS) is a powerful element-specific technique to determine the composition and chemical state of all elements in an involatile sample. However, for elements such as carbon, the wide variety of chemical states produce complex spectra that are difficult to interpret, consequently concealing important information due to the uncertainty in signal identity. Here we report a process whereby chemical modification of carbon structures with electron withdrawing groups can reveal this information, providing accurate, highly refined fitting models far more complex than previously possible. This method is demonstrated with functionalised ionic liquids bearing chlorine or trifluoromethane groups that shift electron density from targeted locations. By comparing the C 1s spectra of non-functional ionic liquids to their functional analogues, a series of difference spectra can be produced to identify exact binding energies of carbon photoemissions, which can be used to improve the C 1s peak fitting of both samples. Importantly, ionic liquids possess ideal chemical and physical properties, which enhance this methodology to enable significant progress in XPS peak fitting and data interpretation.
Collapse
Affiliation(s)
- Coby J Clarke
- School of Chemistry, The University of Nottingham, University Park, Nottingham, UK.
| | | | | | | | | | | |
Collapse
|
7
|
Heller BSJ, Kolbeck C, Niedermaier I, Dommer S, Schatz J, Hunt P, Maier F, Steinrück HP. Surface Enrichment in Equimolar Mixtures of Non-Functionalized and Functionalized Imidazolium-Based Ionic Liquids. Chemphyschem 2018; 19:1733-1745. [PMID: 29645340 PMCID: PMC6175172 DOI: 10.1002/cphc.201800216] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Indexed: 11/30/2022]
Abstract
For equimolar mixtures of ionic liquids with imidazolium‐based cations of very different electronic structure, we observe very pronounced surface enrichment effects by angle‐resolved X‐ray photoelectron spectroscopy (XPS). For a mixture with the same anion, that is, 1‐methyl‐3‐octylimidazolium hexafluorophosphate+1,3‐di(methoxy)imidazolium hexafluorophosphate ([C8C1Im][PF6]+[(MeO)2Im][PF6]), we find a strong enrichment of the octyl chain‐containing [C8C1Im]+ cation and a corresponding depletion of the [(MeO)2Im]+ cation in the topmost layer. For a mixture with different cations and anions, that is, [C8C1Im][Tf2N]+[(MeO)2Im][PF6], we find both surface enrichment of the [C8C1Im]+ cation and the [Tf2N]− (bis[(trifluoromethyl)sulfonyl]imide) anion, while [(MeO)2Im]+ and [PF6]− are depleted from the surface. We propose that the observed behavior in these mixtures is due to a lowering of the surface tension by the enriched components. Interestingly, we observe pronounced differences in the chemical shifts of the imidazolium ring signals of the [(MeO)2Im]+ cations as compared to the non‐functionalized cations. Calculations of the electronic structure and the intramolecular partial charge distribution of the cations contribute to interpreting these shifts for the two different cations.
Collapse
Affiliation(s)
- Bettina S J Heller
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058, Erlangen, Germany
| | - Claudia Kolbeck
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058, Erlangen, Germany
| | - Inga Niedermaier
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058, Erlangen, Germany
| | - Sabine Dommer
- Lehrstuhl für Organische Chemie I, Friedrich-Alexander-Universität Erlangen-Nürnberg, Nikolaus-Fiebiger-Straße 10, 91058, Erlangen, Germany
| | - Jürgen Schatz
- Lehrstuhl für Organische Chemie I, Friedrich-Alexander-Universität Erlangen-Nürnberg, Nikolaus-Fiebiger-Straße 10, 91058, Erlangen, Germany
| | - Patricia Hunt
- Chemistry Department, Imperial College London, SW72AZ, London, United Kingdom
| | - Florian Maier
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058, Erlangen, Germany
| | - Hans-Peter Steinrück
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 3, 91058, Erlangen, Germany
| |
Collapse
|
8
|
Black JM, Come J, Bi S, Zhu M, Zhao W, Wong AT, Noh JH, Pudasaini PR, Zhang P, Okatan MB, Dai S, Kalinin SV, Rack PD, Ward TZ, Feng G, Balke N. Role of Electrical Double Layer Structure in Ionic Liquid Gated Devices. ACS APPLIED MATERIALS & INTERFACES 2017; 9:40949-40958. [PMID: 29063758 DOI: 10.1021/acsami.7b11044] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Ionic liquid gating of transition metal oxides has enabled new states (magnetic, electronic, metal-insulator), providing fundamental insights into the physics of strongly correlated oxides. However, despite much research activity, little is known about the correlation of the structure of the liquids in contact with the transition metal oxide surface, its evolution with the applied electric potential, and its correlation with the measured electronic properties of the oxide. Here, we investigate the structure of an ionic liquid at a semiconducting oxide interface during the operation of a thin film transistor where the electrical double layer gates the device using experiment and theory. We show that the transition between the ON and OFF states of the amorphous indium gallium zinc oxide transistor is accompanied by a densification and preferential spatial orientation of counterions at the oxide channel surface. This process occurs in three distinct steps, corresponding to ion orientations, and consequently, regimes of different electrical conductivity. The reason for this can be found in the surface charge densities on the oxide surface when different ion arrangements are present. Overall, the field-effect gating process is elucidated in terms of the interfacial ionic liquid structure, and this provides unprecedented insight into the working of a liquid gated transistor linking the nanoscopic structure to the functional properties. This knowledge will enable both new ionic liquid design as well as advanced device concepts.
Collapse
Affiliation(s)
| | | | - Sheng Bi
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology (HUST) , Wuhan 430074, China
| | - Mengyang Zhu
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology (HUST) , Wuhan 430074, China
| | - Wei Zhao
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology (HUST) , Wuhan 430074, China
| | | | | | | | | | | | | | | | | | | | - Guang Feng
- State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology (HUST) , Wuhan 430074, China
| | | |
Collapse
|
9
|
Biedron AB, Garfunkel EL, Castner EW, Rangan S. Ionic liquid ultrathin films at the surface of Cu(100) and Au(111). J Chem Phys 2017; 146:054704. [DOI: 10.1063/1.4975101] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Aleksandra B. Biedron
- Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854, USA
| | - Eric L. Garfunkel
- Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854, USA
| | - Edward W. Castner
- Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854, USA
| | - Sylvie Rangan
- Department of Physics and Astronomy and Laboratory for Surface Modification, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, USA
| |
Collapse
|
10
|
Nakajima K, Zolboo E, Ohashi T, Lísal M, Kimura K. Perfect Composition Depth Profiling of Ionic Liquid Surfaces Using High-resolution RBS/ERDA. ANAL SCI 2016; 32:1089-1094. [PMID: 27725609 DOI: 10.2116/analsci.32.1089] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In order to reveal the surface structures of large molecular ionic liquids (ILs), the near-surface elemental depth distributions of 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([CnC1Im][Tf2N], n = 2, 6, 10) were studied using high-resolution Rutherford backscattering spectroscopy (HRBS) in combination with high-resolution elastic recoil detection analysis (HR-ERDA). The elemental depth profiles of all constituent elements, including hydrogen, were derived from HR-ERDA/HRBS measurements, so that the profiles would reproduce both HR-ERDA and HRBS spectra simultaneously. The derived elemental depth profiles agree with state-of-the-art molecular dynamics simulations, indicating the feasibility of this method. A controversy concerning the preferential orientation of [C2C1Im] at the surface has been resolved by this new combination analysis; namely, the [C2C1Im] cation has a preferential orientation with the ethyl chain pointing towards the vacuum in the topmost molecular layer.
Collapse
|
11
|
Amith WD, Hettige JJ, Castner EW, Margulis CJ. Structures of Ionic Liquids Having Both Anionic and Cationic Octyl Tails: Lamellar Vacuum Interface vs Sponge-Like Bulk Order. J Phys Chem Lett 2016; 7:3785-3790. [PMID: 27607189 DOI: 10.1021/acs.jpclett.6b01763] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Numerous experimental and computational studies have shown that the structure of ionic liquids is significantly influenced by confinement and by interactions with interfaces. The nature of the interface can affect the immediate ordering of cations and anions, changing important rheological characteristics relevant to lubrication. Most studies suggest that such changes are local or short-ranged and that bulk properties are reestablished on a length scale of a few nanometers. The current study focuses on the 1-methyl-3-octylimidazolium octylsulfate ionic liquid for which both the cation and anion have moderate length linear alkyl tails. For this system, we find that the bulk phase is dominated by the very common sponge-like morphology characteristic of many ionic liquids. However, at the vacuum interface, a lamellar structure is observed that is not restricted to the vicinity of the surface but instead extends across the full 9 nm slab of our simulation. We suspect that in reality it could extend significantly beyond this.
Collapse
Affiliation(s)
| | - Jeevapani J Hettige
- Department of Chemistry, University of Iowa , Iowa City, Iowa 52242, 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
| |
Collapse
|
12
|
Holzweber M, Unger WES, Hodoroaba VD. Ionic Liquids as a Reference Material Candidate for the Quick Performance Check of Energy Dispersive X-ray Spectrometers for the Low Energy Range below 1 keV. Anal Chem 2016; 88:6967-70. [PMID: 27336962 PMCID: PMC4955014 DOI: 10.1021/acs.analchem.6b01444] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Ionic
liquids (ILs) are proposed as simple and efficient test materials
to evaluate the performance of energy dispersive X-ray spectrometers
(EDS) in the low energy range below 1 keV. By only one measurement,
C Kα, N Kα, O Kα, and F Kα X-ray lines can
be excited. Additionally, the S Kα line at 2.3 keV and, particularly,
the S L series at 149 eV complete the picture with X-ray lines offered
by the selected ILs. The well-known (certifiable) elemental composition
of the ILs selected in the present study can be used to check the
accuracy of results produced with the available EDS quantification
routines in the low energy range, simultaneously, for several low
atomic number elements. A comparison with other reference materials
in use for testing the performance of EDS in the low energy range
is included.
Collapse
Affiliation(s)
- Markus Holzweber
- Federal Institute for Materials Research and Testing (BAM) , Division 6.1 Surface Analysis and Interfacial Chemistry, Unter den Eichen 44-46, 12203 Berlin, Germany.,Vienna University of Technology , Institute of Chemical Technologies und Analytics, Getreidemarkt 9/164AC, 1060 Vienna, Austria
| | - Wolfgang E S Unger
- Federal Institute for Materials Research and Testing (BAM) , Division 6.1 Surface Analysis and Interfacial Chemistry, Unter den Eichen 44-46, 12203 Berlin, Germany
| | - Vasile-Dan Hodoroaba
- Federal Institute for Materials Research and Testing (BAM) , Division 6.1 Surface Analysis and Interfacial Chemistry, Unter den Eichen 44-46, 12203 Berlin, Germany
| |
Collapse
|
13
|
Tesa-Serrate MA, Smoll EJ, Minton TK, McKendrick KG. Atomic and Molecular Collisions at Liquid Surfaces. Annu Rev Phys Chem 2016; 67:515-40. [PMID: 27090845 DOI: 10.1146/annurev-physchem-040215-112355] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The gas-liquid interface remains one of the least explored, but nevertheless most practically important, environments in which molecular collisions take place. These molecular-level processes underlie many bulk phenomena of fundamental and applied interest, spanning evaporation, respiration, multiphase catalysis, and atmospheric chemistry. We review here the research that has, during the past decade or so, been unraveling the molecular-level mechanisms of inelastic and reactive collisions at the gas-liquid interface. Armed with the knowledge that such collisions with the outer layers of the interfacial region can be unambiguously distinguished, we show that the scattering of gas-phase projectiles is a promising new tool for the interrogation of liquid surfaces with extreme surface sensitivity. Especially for reactive scattering, this method also offers absolute chemical selectivity for the groups that react to produce a specific observed product.
Collapse
Affiliation(s)
- Maria A Tesa-Serrate
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom;
| | - Eric J Smoll
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717;
| | - Timothy K Minton
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717;
| | - Kenneth G McKendrick
- Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom;
| |
Collapse
|
14
|
Seo S, Park J, Kang YC. Chemical Analysis of Ionic Liquids Using Photoelectron Spectroscopy. B KOREAN CHEM SOC 2016. [DOI: 10.1002/bkcs.10683] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- SungYong Seo
- Department of Chemistry; Pukyong National University; Busan 608-737 Republic of Korea
| | - Juyun Park
- Department of Chemistry; Pukyong National University; Busan 608-737 Republic of Korea
| | - Yong-Cheol Kang
- Department of Chemistry; Pukyong National University; Busan 608-737 Republic of Korea
| |
Collapse
|
15
|
Blundell RK, Delorme AE, Smith EF, Licence P. An ARXPS and ERXPS study of quaternary ammonium and phosphonium ionic liquids: utilising a high energy Ag Lα′ X-ray source. Phys Chem Chem Phys 2016; 18:6122-31. [DOI: 10.1039/c5cp07089a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A series of ammonium- and phosphonium-based ionic liquids have been probed using X-ray photoelectron spectroscopy (XPS) with a high energy Ag Lα′ X-ray source.
Collapse
Affiliation(s)
- Rebecca K. Blundell
- The GlaxoSmithKline Carbon Neutral Laboratory
- School of Chemistry
- The University of Nottingham
- Nottingham NG7 2RD
- UK
| | - Astrid E. Delorme
- The GlaxoSmithKline Carbon Neutral Laboratory
- School of Chemistry
- The University of Nottingham
- Nottingham NG7 2RD
- UK
| | - Emily F. Smith
- The GlaxoSmithKline Carbon Neutral Laboratory
- School of Chemistry
- The University of Nottingham
- Nottingham NG7 2RD
- UK
| | - Peter Licence
- The GlaxoSmithKline Carbon Neutral Laboratory
- School of Chemistry
- The University of Nottingham
- Nottingham NG7 2RD
- UK
| |
Collapse
|
16
|
Hjalmarsson N, Wallinder D, Glavatskih S, Atkin R, Aastrup T, Rutland MW. Weighing the surface charge of an ionic liquid. NANOSCALE 2015; 7:16039-16045. [PMID: 26370450 DOI: 10.1039/c5nr03965g] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Electrochemical quartz crystal microbalance has been used to measure changes in the composition of the capacitive electrical double layer for 1-ethyl-3-methylimidazolium tris(pentafluoroethyl)-trifluorophosphate, an ionic liquid, in contact with a gold electrode surface as a function of potential. The mass difference between the cation and anion means that the technique can effectively "weigh" the surface charge accurately with high temporal resolution. This reveals quantitatively how changing the potential alters the ratio of cations and anions associated with the electrode surface, and thus the charge per unit area, as well as the kinetics associated with these interfacial processes. The measurements reveal that it is diffusion of co-ions into the interfacial region rather than expulsion of counterions that controls the relaxation. The measured potential dependent double layer capacitance experimentally validates recent theoretical predictions for counterion overscreening (low potentials) and crowding (high potentials) at electrode surfaces. This new capacity to quantitatively measure ion composition is critical for ionic liquid applications ranging from batteries, capacitors and electrodeposition through to boundary layer structure in tribology, and more broadly provides new insight into interfacial processes in concentrated electrolyte solutions.
Collapse
Affiliation(s)
- Nicklas Hjalmarsson
- Surface and Corrosion Science, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | | | | | | | | | | |
Collapse
|
17
|
Konieczny JK, Szefczyk B. Structure of Alkylimidazolium-Based Ionic Liquids at the Interface with Vacuum and Water—A Molecular Dynamics Study. J Phys Chem B 2015; 119:3795-807. [DOI: 10.1021/jp510843m] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jan K. Konieczny
- Advanced Materials Engineering and Modelling Group, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Borys Szefczyk
- Advanced Materials Engineering and Modelling Group, Faculty of Chemistry, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| |
Collapse
|
18
|
Otero I, López ER, Reichelt M, Villanueva M, Salgado J, Fernández J. Ionic liquids based on phosphonium cations as neat lubricants or lubricant additives for a steel/steel contact. ACS APPLIED MATERIALS & INTERFACES 2014; 6:13115-13128. [PMID: 25046076 DOI: 10.1021/am502980m] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
After doing several miscibility essays with eight ionic liquids (ILs) and four base oils, the ILs tri(butyl)ethylphosphonium diethylphosphate [P4,4,4,2][C2C2PO4] and trihexyl(tetradecyl)phosphonium tris(pentafluoroethyl)trifluorophosphate [P6,6,6,14][(C2F5)3PF3] were selected to be studied as lubricant additives. The neat IL [P4,4,4,2][C2C2PO4], the base oils, and several blends were characterized in terms of density, viscosity, and thermal stability. The tribological performance of the miscible base oil/IL blends (1 wt %) and the neat [P4,4,4,2][C2C2PO4] were evaluated for the lubrication of an AISI 420 steel-100Cr6 steel contact pair. The friction coefficients and wear volumes obtained are also compared with those corresponding to the pure base oils and their mixtures with conventional additive zinc dialkyldithiophosphate (ZDDP). As neat lubricants, [P4,4,4,2][C2C2PO4] showed the best antifriction ability, whereas in terms of wear, better results were obtained with [P6,6,6,14][(C2F5)3PF3]. However, higher improvements in both friction and wear were found for blends containing [P4,4,4,2][C2C2PO4]. XPS analyses of the worn surfaces lubricated with these mixtures indicated the presence of phosphorus in the tribofilm formed on the wear track. However, this compound was slightly detected on tribosamples lubricated with blends containing [P6,6,6,14][(C2F5)3PF3].
Collapse
Affiliation(s)
- Inés Otero
- Laboratory of Thermophysical Properties of Fluids and Biomaterials, Department of Applied Physics, Faculty of Physics, University of Santiago de Compostela , 15782 Santiago de Compostela, Spain
| | | | | | | | | | | |
Collapse
|
19
|
Andersson G, Ridings C. Ion Scattering Studies of Molecular Structure at Liquid Surfaces with Applications in Industrial and Biological Systems. Chem Rev 2014; 114:8361-87. [DOI: 10.1021/cr400417f] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Gunther Andersson
- Centre
for NanoScale Science
and Technology, Flinders University, Adelaide, South Australia 5001, Australia
| | - Christiaan Ridings
- Centre
for NanoScale Science
and Technology, Flinders University, Adelaide, South Australia 5001, Australia
| |
Collapse
|
20
|
Ridings C, Warr GG, Andersson GG. Composition of the outermost layer and concentration depth profiles of ammonium nitrate ionic liquid surfaces. Phys Chem Chem Phys 2014; 14:16088-95. [PMID: 23103987 DOI: 10.1039/c2cp43035e] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Differences in the surface structure of protic ionic liquids (ILs) with three different cations and a common anion; ethyl-, propyl- and 2-hydroxyethyl- (or ethanol-) ammonium nitrate (EAN, PAN and EtAN, respectively) have been observed by neutral impact collision ion scattering spectroscopy (NICISS) and metastable induced electron spectroscopy/ultraviolet photoelectron spectroscopy (MIES/UPS). NICISS is used to determine the concentration depth profiles of the elements in each IL and it reveals an enrichment of cation alkyl chains of PAN and EtAN in the outermost layer compared to EAN, and a corresponding depletion of nitrate from the outermost layer of the EtAN surface. MIES probes the molecular orbitals of only the species in the outermost layer of a sample and confirms that, while both the anion and the cation are present to some degree at the surface of all three ILs, the cation is enriched to a greater extent at the surface of PAN and EtAN compared to EAN.
Collapse
Affiliation(s)
- Christiaan Ridings
- Centre for NanoScale Science and Technology, Flinders University, SA, Australia
| | | | | |
Collapse
|
21
|
Affiliation(s)
- Maxim V Fedorov
- Department of Physics, Scottish University Physics Alliance (SUPA), University of Strathclyde , John Anderson Bldg, 107 Rottenrow, Glasgow, G4 0NG United Kingdom
| | | |
Collapse
|
22
|
Paredes X, Fernández J, Pádua AAH, Malfreyt P, Malberg F, Kirchner B, Pensado AS. Bulk and Liquid–Vapor Interface of Pyrrolidinium-Based Ionic Liquids: A Molecular Simulation Study. J Phys Chem B 2014; 118:731-42. [DOI: 10.1021/jp406651f] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xavier Paredes
- Laboratorio de
Propiedades Termofı́sicas, Departamento de
Fı́sica Aplicada, Universidade de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
| | - Josefa Fernández
- Laboratorio de
Propiedades Termofı́sicas, Departamento de
Fı́sica Aplicada, Universidade de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
| | - Agílio A. H. Pádua
- Institut de Chimie
de Clermont-Ferrand, Equipe Thermodynamique et Interactions Moléculaires, Clermont Université, Université Blaise Pascal, BP 80026, 63171 Aubiere, France
- CNRS, UMR6296 ICCF, BP 80026, F-63171 Aubière, France
| | - Patrice Malfreyt
- Institut de Chimie
de Clermont-Ferrand, Equipe Thermodynamique et Interactions Moléculaires, Clermont Université, Université Blaise Pascal, BP 80026, 63171 Aubiere, France
- CNRS, UMR6296 ICCF, BP 80026, F-63171 Aubière, France
| | - Friedrich Malberg
- Mulliken Center
for Theoretical Chemistry, Institut für Physikalische und Theoretische
Chemie, Universität Bonn, Beringstrasse 4+6, D-53115 Bonn, Germany
| | - Barbara Kirchner
- Mulliken Center
for Theoretical Chemistry, Institut für Physikalische und Theoretische
Chemie, Universität Bonn, Beringstrasse 4+6, D-53115 Bonn, Germany
| | - Alfonso S. Pensado
- Laboratorio de
Propiedades Termofı́sicas, Departamento de
Fı́sica Aplicada, Universidade de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
- Mulliken Center
for Theoretical Chemistry, Institut für Physikalische und Theoretische
Chemie, Universität Bonn, Beringstrasse 4+6, D-53115 Bonn, Germany
| |
Collapse
|
23
|
Villar-Garcia IJ, Fearn S, De Gregorio GF, Ismail NL, Gschwend FJV, McIntosh AJS, Lovelock KRJ. The ionic liquid–vacuum outer atomic surface: a low-energy ion scattering study. Chem Sci 2014. [DOI: 10.1039/c4sc00640b] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We have identified elements present in the ionic liquid–vacuum outer atomic surface of 23 ionic liquids using high sensitivity low-energy ion scattering (LEIS), a very surface sensitive technique.
Collapse
Affiliation(s)
| | - Sarah Fearn
- Department of Materials
- Imperial College London
- , UK
| | | | | | | | | | | |
Collapse
|
24
|
Hessey SG, Jones RG. On the evaporation, bonding, and adsorbate capture of an ionic liquid on Au(111). Chem Sci 2013. [DOI: 10.1039/c3sc00072a] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
|
25
|
|
26
|
Ridings C, Lockett V, Andersson G. Comparing the charge distribution along the surface normal in the [C6mim]+ ionic liquid with different anions. Colloids Surf A Physicochem Eng Asp 2012. [DOI: 10.1016/j.colsurfa.2012.01.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
27
|
Lovelock KRJ. Influence of the ionic liquid/gas surface on ionic liquid chemistry. Phys Chem Chem Phys 2012; 14:5071-89. [PMID: 22349469 DOI: 10.1039/c2cp23851a] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Applications such as gas storage, gas separation, NP synthesis and supported ionic liquid phase catalysis depend upon the interaction of different species with the ionic liquid/gas surface. Consequently, these applications cannot proceed to the full extent of their potential without a profound understanding of the surface structure and properties. As a whole, this perspective contains more questions than answers, which demonstrates the current state of the field. Throughout this perspective, crucial questions are posed and a roadmap is proposed to answer these questions. A critical analysis is made of the field of ionic liquid/gas surface structure and properties, and a number of design rules are mined. The effects of ionic additives on the ionic liquid/gas surface structure are presented. A possible driving force for surface formation is discussed that has, to the best of my knowledge, not been postulated in the literature to date. This driving force suggests that for systems composed solely of ions, the rules for surface formation of dilute electrolytes do not apply. The interaction of neutral additives with the ionic liquid/gas surface is discussed. Particular attention is focussed upon H(2)O and CO(2), vital additives for many applications of ionic liquids. Correlations between ionic liquid/gas surface structure and properties, ionic liquid surfaces plus additives, and ionic liquid applications are given.
Collapse
Affiliation(s)
- Kevin R J Lovelock
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK.
| |
Collapse
|
28
|
Perkin S, Crowhurst L, Niedermeyer H, Welton T, Smith AM, Gosvami NN. Self-assembly in the electrical double layer of ionic liquids. Chem Commun (Camb) 2011; 47:6572-4. [PMID: 21573282 DOI: 10.1039/c1cc11322d] [Citation(s) in RCA: 177] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We have studied the structure of two ionic liquids confined between negatively charged mica sheets. Both liquids exhibit interfacial layering, however the repeat distance is dramatically different for the two liquids. Our results suggest a transition from alternating cation-anion monolayers to tail-to-tail cation bilayers when the length of the cation hydrocarbon chain is increased.
Collapse
Affiliation(s)
- Susan Perkin
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK.
| | | | | | | | | | | |
Collapse
|
29
|
Pensado AS, Gomes MFC, Lopes JNC, Malfreyt P, Pádua AAH. Effect of alkyl chain length and hydroxyl group functionalization on the surface properties of imidazolium ionic liquids. Phys Chem Chem Phys 2011; 13:13518-26. [DOI: 10.1039/c1cp20563c] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
|
30
|
Ridings C, Lockett V, Andersson G. Effect of the aliphatic chain length on electrical double layer formation at the liquid/vacuum interface in the [Cnmim][BF4] ionic liquid series. Phys Chem Chem Phys 2011; 13:17177-84. [DOI: 10.1039/c1cp20910h] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
31
|
Ridings C, Lockett V, Andersson G. Significant changes of the charge distribution at the surface of an ionic liquid due to the presence of small amounts of water. Phys Chem Chem Phys 2011; 13:21301-7. [DOI: 10.1039/c1cp22551k] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|