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Kim M, Tetteh EB, Savan A, Xiao B, Ludwig A, Schuhmann W, Chung TD. Reorganization energy in a polybromide ionic liquid measured by scanning electrochemical cell microscopy. J Chem Phys 2023; 158:134707. [PMID: 37031154 DOI: 10.1063/5.0143018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023] Open
Abstract
Room temperature ionic liquids (RT-ILs) are promising electrolytes for electrocatalysis. Understanding the effects of the electrode–electrolyte interface structure on electrocatalysis in RT-ILs is important. Ultrafast mass transport of redox species in N-methyl- N-ethyl-pyrrolidinium polybromide (MEPBr2n+1) enabled evaluation of the reorganization energy ( λ), which reflects the solvation structure in the inner Helmholtz plane (IHP). λ was achieved by fitting the electron transfer rate-limited voltammogram at a Pt ultramicroelectrode (UME) to the Marcus–Hush–Chidsey model for heterogeneous electron transfer kinetics. However, it is time-consuming or even impossible to prepare electrode materials, including alloys of numerous compositions in the form of UME, for each experiment. Herein, we report a method to evaluate the λ of MEPBr2n+1 by scanning electrochemical cell microscopy (SECCM), which allows high throughput electrochemical measurements using a single electrode with high spatial resolution. Fast mass transport in the nanosized SECCM tip is critical for achieving heterogeneous electron transfer-limited voltammograms. Furthermore, investigating λ on a high-entropy alloy materials library composed of Pt, Pd, Ru, Ir, and Ag suggests a negative correlation between λ and the work function. Given that the potential of zero charge correlates with the work function of electrodes, this can be attributed to the surface-charge sensitive ionic structure in the IHP of MEPBr2n+1, modulating the solvation energy of the redox-active species in the IHP.
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Affiliation(s)
- Moonjoo Kim
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
- Analytical Chemistry – Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstraße 150, Bochum, Germany
| | - Emmanuel Batsa Tetteh
- Analytical Chemistry – Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstraße 150, Bochum, Germany
| | - Alan Savan
- Chair for Materials Discovery and Interfaces, Institute for Materials, Faculty of Mechanical Engineering, Ruhr University Bochum, Universitätsstraße 150, Bochum, Germany
| | - Bin Xiao
- Chair for Materials Discovery and Interfaces, Institute for Materials, Faculty of Mechanical Engineering, Ruhr University Bochum, Universitätsstraße 150, Bochum, Germany
| | - Alfred Ludwig
- Chair for Materials Discovery and Interfaces, Institute for Materials, Faculty of Mechanical Engineering, Ruhr University Bochum, Universitätsstraße 150, Bochum, Germany
- ZGH, Ruhr University Bochum, Universitätsstraße 150, Bochum, Germany
| | - Wolfgang Schuhmann
- Analytical Chemistry – Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstraße 150, Bochum, Germany
| | - Taek Dong Chung
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
- Advanced Institute of Convergence Technology, Suwon-si, Gyeonggi-do 16229, Republic of Korea
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2
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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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3
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Luo Y, Pang AP, Lu X. Liquid-Solid Interfaces under Dynamic Shear Flow: Recent Insights into the Interfacial Slip. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:4473-4482. [PMID: 35377658 DOI: 10.1021/acs.langmuir.2c00037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The development of micro/nanofluidic techniques has recently revived interest in dynamic shear flow at liquid-solid interfaces. When the nature of the liquid-solid boundaries was revisited, the slip of the fluids relative to the solid wall was predicted theoretically and confirmed experimentally. This indicates that the molecular-level structures of the liquid-solid interfaces will be influenced by the liquid flow over certain temporal and spatial criteria. However, the fluid flow at the boundary layer still cannot be precisely predicted and effectively controlled, somehow limiting its practical applications. Here, we summarize the recent advances for the microscopic structures at the liquid-solid interfaces upon shear flow. Special attention was given to a second-order nonlinear optical technique, sum frequency generation vibrational spectroscopy, which is a powerful tool for exploring the molecular-level structures and structural dynamics at the liquid-solid interfaces and offering new insights into the molecular mechanisms of the fluid slip at the interfaces. Moreover, we discuss the possible approaches for controlling the interfacial slip at the molecular level and highlight the current challenges and opportunities. Although the theoretical framework of the slip at the liquid-solid interfaces is still incomplete, we hope that this Perspective will complement and enhance our understanding of various interfacial properties and phenomena with respect to practical non-equilibrium dynamic processes happening at the interfaces.
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Affiliation(s)
- Yongsheng Luo
- The State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, Jiangsu, P. R. China
| | - Ai-Ping Pang
- The State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, Jiangsu, P. R. China
| | - Xiaolin Lu
- The State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, Jiangsu, P. R. China
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4
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Kim M, Park S, Chung TD. Heterogeneous electron transfer reorganization energy at the inner Helmholtz plane in a polybromide redox-active ionic liquid. Chem Sci 2022; 13:8821-8828. [PMID: 35975145 PMCID: PMC9350599 DOI: 10.1039/d2sc01410f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 06/30/2022] [Indexed: 11/21/2022] Open
Abstract
In ionic liquids (ILs), the electric double layer (EDL) is where heterogeneous electron transfer (ET) occurs. Nevertheless, the relationship between the EDL structure and its kinetics has been rarely studied, especially for ET taking place in the inner Helmholtz plane (IHP). This is largely because of the lack of an appropriate model system for experiments. In this work, we determined the reorganization energy (λ) of Br2 reduction in a redox-active IL 1-ethyl-1-methylpyrrolidinium polybromide (MEPBr2n+1) based on the Marcus–Hush–Chidsey model. Exceptionally fast mass transport of Br2 in MEPBr2n+1 allows voltammograms to be obtained in which the current plateau is regulated by electron-transfer kinetics. This enables investigation of the microscopic environment in the IHP of the IL affecting electrocatalytic reactions through reorganization energy. As a demonstration, TiO2-modified Pt was employed to show pH-dependent reorganization energy, which suggests the switch of major ions at the IHP as a function of surface charges of electrodes. Ultrafast transport of Br2 in a polybromide redox-active ionic liquid allows electron transfer-limited voltammograms of Br2 reduction. The reorganization energy at the inner-Helmholtz plane can be determined based on the Marcus–Hush–Chidsey model.![]()
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Affiliation(s)
- Moonjoo Kim
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
| | - Sangmee Park
- Program in Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University, Suwon-si, Gyeonggi-do 16229, Republic of Korea
| | - Taek Dong Chung
- Department of Chemistry, Seoul National University, Seoul 08826, Republic of Korea
- Program in Nano Science and Technology, Graduate School of Convergence Science and Technology, Seoul National University, Suwon-si, Gyeonggi-do 16229, Republic of Korea
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5
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Watanabe S, Pilkington GA, Oleshkevych A, Pedraz P, Radiom M, Welbourn R, Glavatskih S, Rutland MW. Interfacial structuring of non-halogenated imidazolium ionic liquids at charged surfaces: effect of alkyl chain length. Phys Chem Chem Phys 2020; 22:8450-8460. [DOI: 10.1039/d0cp00360c] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Control of the interfacial structures of ionic liquids (ILs) at charged interfaces is important to many of their applications, including in energy storage solutions, sensors and advanced lubrication technologies utilising electric fields.
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Affiliation(s)
- Seiya Watanabe
- Division of Surface and Corrosion Science
- School of Engineering Sciences in Chemistry
- Biotechnology and Health
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
| | - Georgia A. Pilkington
- Division of Surface and Corrosion Science
- School of Engineering Sciences in Chemistry
- Biotechnology and Health
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
| | - Anna Oleshkevych
- Division of Surface and Corrosion Science
- School of Engineering Sciences in Chemistry
- Biotechnology and Health
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
| | - Patricia Pedraz
- Division of Surface and Corrosion Science
- School of Engineering Sciences in Chemistry
- Biotechnology and Health
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
| | - Milad Radiom
- Division of Surface and Corrosion Science
- School of Engineering Sciences in Chemistry
- Biotechnology and Health
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
| | - Rebecca Welbourn
- ISIS Neutron & Muon Source
- Rutherford Appleton Laboratory
- STFC
- Didcot
- UK
| | - Sergei Glavatskih
- System and Component Design
- Department of Machine Design
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
- Sweden
| | - Mark W. Rutland
- Division of Surface and Corrosion Science
- School of Engineering Sciences in Chemistry
- Biotechnology and Health
- KTH Royal Institute of Technology
- SE-100 44 Stockholm
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Humbert C, Noblet T, Dalstein L, Busson B, Barbillon G. Sum-Frequency Generation Spectroscopy of Plasmonic Nanomaterials: A Review. MATERIALS 2019; 12:ma12050836. [PMID: 30871058 PMCID: PMC6427399 DOI: 10.3390/ma12050836] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 03/04/2019] [Accepted: 03/05/2019] [Indexed: 11/16/2022]
Abstract
We report on the recent scientific research contribution of non-linear optics based on Sum-Frequency Generation (SFG) spectroscopy as a surface probe of the plasmonic properties of materials. In this review, we present a general introduction to the fundamentals of SFG spectroscopy, a well-established optical surface probe used in various domains of physical chemistry, when applied to plasmonic materials. The interest of using SFG spectroscopy as a complementary tool to surface-enhanced Raman spectroscopy in order to probe the surface chemistry of metallic nanoparticles is illustrated by taking advantage of the optical amplification induced by the coupling to the localized surface plasmon resonance. A short review of the first developments of SFG applications in nanomaterials is presented to span the previous emergent literature on the subject. Afterwards, the emphasis is put on the recent developments and applications of the technique over the five last years in order to illustrate that SFG spectroscopy coupled to plasmonic nanomaterials is now mature enough to be considered a promising research field of non-linear plasmonics.
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Affiliation(s)
- Christophe Humbert
- Univ Paris-Sud, Université Paris-Saclay, Laboratoire de Chimie Physique, CNRS, Batiment 201 P2, 91405 Orsay, France.
| | - Thomas Noblet
- Univ Paris-Sud, Université Paris-Saclay, Laboratoire de Chimie Physique, CNRS, Batiment 201 P2, 91405 Orsay, France.
| | - Laetitia Dalstein
- Univ Paris-Sud, Université Paris-Saclay, Laboratoire de Chimie Physique, CNRS, Batiment 201 P2, 91405 Orsay, France.
| | - Bertrand Busson
- Univ Paris-Sud, Université Paris-Saclay, Laboratoire de Chimie Physique, CNRS, Batiment 201 P2, 91405 Orsay, France.
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7
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Radiom M. Ionic liquid–solid interface and applications in lubrication and energy storage. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.01.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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8
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Anomalous Interfacial Structuring of a Non-Halogenated Ionic Liquid: Effect of Substrate and Temperature. COLLOIDS AND INTERFACES 2018. [DOI: 10.3390/colloids2040060] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We investigate the interfacial properties of the non-halogenated ionic liquid (IL), trihexyl(tetradecyl)phosphonium bis(mandelato)borate, [P6,6,6,14][BMB], in proximity to solid surfaces, by means of surface force measurement. The system consists of sharp atomic force microscopy (AFM) tips interacting with solid surfaces of mica, silica, and gold. We find that the force response has a monotonic form, from which a characteristic steric decay length can be extracted. The decay length is comparable with the size of the ions, suggesting that a layer is formed on the surface, but that it is diffuse. The long alkyl chains of the cation, the large size of the anion, as well as crowding of the cations at the surface of negatively charged mica, are all factors which are likely to oppose the interfacial stratification which has, hitherto, been considered a characteristic of ionic liquids. The variation in the decay length also reveals differences in the layer composition at different surfaces, which can be related to their surface charge. This, in turn, allows the conclusion that silica has a low surface charge in this aprotic ionic liquid. Furthermore, the effect of temperature has been investigated. Elevating the temperature to 40 °C causes negligible changes in the interaction. At 80 °C and 120 °C, we observe a layering artefact which precludes further analysis, and we present the underlying instrumental origin of this rather universal artefact.
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9
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Chowdhury AU, Liu F, Watson BR, Ashkar R, Katsaras J, Collier CP, Lutterman DA, Ma YZ, Calhoun TR, Doughty B. Flexible approach to vibrational sum-frequency generation using shaped near-infrared light. OPTICS LETTERS 2018; 43:2038-2041. [PMID: 29714740 PMCID: PMC6343496 DOI: 10.1364/ol.43.002038] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 03/03/2018] [Indexed: 05/28/2023]
Abstract
We describe a new approach that expands the utility of vibrational sum-frequency generation (vSFG) spectroscopy using shaped near-infrared (NIR) laser pulses. We demonstrate that arbitrary pulse shapes can be specified to match experimental requirements without the need for changes to the optical alignment. In this way, narrowband NIR pulses as long as 5.75 ps are readily generated, with a spectral resolution of about 2.5 cm-1, an improvement of approximately a factor of 3 compared to a typical vSFG system. Moreover, the utility of having complete control over the NIR pulse characteristics is demonstrated through nonresonant background suppression from a metallic substrate by generating an etalon waveform in the pulse shaper. The flexibility afforded by switching between arbitrary NIR waveforms at the sample position with the same instrument geometry expands the type of samples that can be studied without extensive modifications to existing apparatuses or large investments in specialty optics.
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Affiliation(s)
- Azhad U. Chowdhury
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831
| | - Fangjie Liu
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831
| | - Brianna R. Watson
- Department of Chemistry, University of Tennessee, Knoxville, TN, 37996
| | - Rana Ashkar
- Department of Physics, Virginia Tech, Blacksburg, VA 24061
| | - John Katsaras
- Large Scale Structures Group, Neutron Sciences Directorate and Shull Wollan Center: A Joint Institute for Neutron Science, Oak Ridge National Laboratory, Oak Ridge, TN 37831
| | - C. Patrick Collier
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831
| | - Daniel A. Lutterman
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831
| | - Ying-Zhong Ma
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831
| | - Tessa R. Calhoun
- Department of Chemistry, University of Tennessee, Knoxville, TN, 37996
| | - Benjamin Doughty
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831
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10
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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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11
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Abstract
Recent advances in experimental and computational techniques have allowed for an accurate description of the adsorption of ionic liquids on metallic electrodes. It is now well-established that they adopt a multilayered structure and that the composition of the layers changes with the potential of the electrode. In some cases, potential-driven ordering transitions in the first adsorbed layer have been observed in experiments probing the interface on the molecular scale or by molecular simulations. This perspective gives an overview of the current understanding of such transitions and of their potential impact on the physical and (electro)chemical processes at the interface. In particular, peaks in the differential capacitance, slow dynamics at the interface, and changes in the reactivity have been reported in electrochemical studies. Interfaces between ionic liquids and metallic electrodes are also highly relevant for their friction properties, the voltage-dependence of which opens the way to exciting applications.
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Affiliation(s)
- Benjamin Rotenberg
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire PHENIX, F-75005, Paris, France
- Réseau sur le Stockage Electrochimique de l'Energie (RS2E), FR CNRS 3459, 80039 Amiens Cedex, France
| | - Mathieu Salanne
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire PHENIX, F-75005, Paris, France
- Réseau sur le Stockage Electrochimique de l'Energie (RS2E), FR CNRS 3459, 80039 Amiens Cedex, France
- Maison de la Simulation, USR 3441, CEA - CNRS - INRIA - Université Paris-Sud -Université de Versailles, F-91191 Gif-sur-Yvette, France
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12
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Abstract
Capacitive energy storage devices are receiving increasing experimental and theoretical attention due to their enormous potential for energy applications. Current research in this field is focused on the improvement of both the energy and the power density of supercapacitors by optimizing the nanostructure of porous electrodes and the chemical structure/composition of the electrolytes. However, the understanding of the underlying correlations and the mechanisms of electric double layer formation near charged surfaces and inside nanoporous electrodes is complicated by the complex interplay of several molecular scale phenomena. This Perspective presents several aspects regarding the experimental and theoretical research in the field, discusses the current atomistic and molecular scale understanding of the mechanisms of energy and charge storage, and provides a brief outlook to the future developments and applications of these devices.
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Affiliation(s)
- Jenel Vatamanu
- Department of Materials Science & Engineering, The University of Utah , 122 S. Central Campus Drive, Salt Lake City, Utah 84112, United States
| | - Dmitry Bedrov
- Department of Materials Science & Engineering, The University of Utah , 122 S. Central Campus Drive, Salt Lake City, Utah 84112, United States
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13
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Ravula S, Baker SN, Kamath G, Baker GA. Ionic liquid-assisted exfoliation and dispersion: stripping graphene and its two-dimensional layered inorganic counterparts of their inhibitions. NANOSCALE 2015; 7:4338-53. [PMID: 25689172 DOI: 10.1039/c4nr01524j] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Research on graphene-monolayers of carbon atoms arranged in a honeycomb lattice-is proceeding at a relentless pace as scientists of both experimental and theoretical bents seek to explore and exploit its superlative attributes, including giant intrinsic charge mobility, record-setting thermal conductivity, and high fracture strength and Young's modulus. Of course, fully exploiting the remarkable properties of graphene requires reliable, large-scale production methods which are non-oxidative and introduce minimal defects, criteria not fully satisfied by current approaches. A major advance in this direction is ionic liquid-assisted exfoliation and dispersion of graphite, leading to the isolation of few- and single-layered graphene sheets with yields two orders of magnitude higher than the earlier liquid-assisted exfoliation approaches using surface energy-matched solvents such as N-methyl-2-pyrrolidone (NMP). In this Minireview, we discuss the emerging use of ionic liquids for the practical exfoliation, dispersion, and modification of graphene nanosheets. These developments lay the foundation for strategies seeking to overcome the many challenges faced by current liquid-phase exfoliation approaches. Early computational and experimental results clearly indicate that these same approaches can readily be extended to inorganic graphene analogues (e.g., BN, MoX2 (X = S, Se, Te), WS2, TaSe2, NbSe2, NiTe2, and Bi2Te3) as well.
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Affiliation(s)
- Sudhir Ravula
- Department of Chemistry, University of Missouri-Columbia, Columbia, MO 65211-7600, USA.
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14
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Roznyatovskaya N, Rupp ABA, Tübke J, Krossing I. Sieving Effects in Electrical Double-Layer Capacitors Based on Neat [Al(hfip)4]−and [NTf2]−Ionic Liquids. ChemElectroChem 2015. [DOI: 10.1002/celc.201500024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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15
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Payal RS, Balasubramanian S. Effect of cation symmetry on the organization of ionic liquids near a charged mica surface. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:284101. [PMID: 24919885 DOI: 10.1088/0953-8984/26/28/284101] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Atomistic molecular dynamics simulations have been carried out to understand the effect of the symmetry of cations on the microscopic organization of ionic liquids near a charged mica surface. Ionic liquids with a 1,3-alkylimidazolium ([C(n)C(m)im](+)) cation and a bis(trifluoromethylsulfonyl)imide ([NTf2](-)) anion were investigated. Apart from symmetry, the length of the alkyl group attached to the cation is found to crucially determine the ion structure near the solid surface. In the first adsorbed layer, the ring planes of cations with shorter alkyl groups (less than four carbon atoms) are oriented either parallel or perpendicular to the surface. However, cations with longer alkyl tails are exclusively observed to have their ring planes parallel to the mica surface. The alkyl groups too show a similar dependence of their orientation on the tail length. Further, symmetric cations with alkyl groups of intermediate length are more highly structured at the interface than their asymmetric counterparts.
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Affiliation(s)
- Rajdeep Singh Payal
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
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16
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Xu S, Xing S, Pei SS, Baldelli S. Sum Frequency Generation Spectroscopy Study of an Ionic Liquid at a Graphene-BaF2 (111) Interface. J Phys Chem B 2014; 118:5203-10. [DOI: 10.1021/jp502500u] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Siyun Xu
- Department
of Chemistry, University of Houston, Houston, Texas 77204-5003, United States
| | - Sirui Xing
- Department
of Electrical and Computer Engineering, University of Houston, Houston, Texas 77204-5003, United States
- Center
for Advanced Materials, University of Houston, Houston, Texas 77204-5003, United States
| | - Shin-Shem Pei
- Department
of Electrical and Computer Engineering, University of Houston, Houston, Texas 77204-5003, United States
- Center
for Advanced Materials, University of Houston, Houston, Texas 77204-5003, United States
| | - Steven Baldelli
- Department
of Chemistry, University of Houston, Houston, Texas 77204-5003, United States
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17
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Affiliation(s)
- Maxim V Fedorov
- Department of Physics, Scottish University Physics Alliance (SUPA), University of Strathclyde , John Anderson Bldg, 107 Rottenrow, Glasgow, G4 0NG United Kingdom
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Kirchner K, Kirchner T, Ivaništšev V, Fedorov M. Electrical double layer in ionic liquids: Structural transitions from multilayer to monolayer structure at the interface. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.05.049] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Peñalber CY, Baker GA, Baldelli S. Sum Frequency Generation Spectroscopy of Imidazolium-Based Ionic Liquids with Cyano-Functionalized Anions at the Solid Salt–Liquid Interface. J Phys Chem B 2013; 117:5939-49. [DOI: 10.1021/jp4019074] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Chariz Y. Peñalber
- Department of Chemistry, University of Houston, Houston, Texas 77204-5003, United
States
| | - Gary A. Baker
- Department of Chemistry, University of Missouri—Columbia, Columbia, Missouri,
65211-7600, United States
| | - Steven Baldelli
- Department of Chemistry, University of Houston, Houston, Texas 77204-5003, United
States
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Baldelli S. Interfacial Structure of Room-Temperature Ionic Liquids at the Solid-Liquid Interface as Probed by Sum Frequency Generation Spectroscopy. J Phys Chem Lett 2013; 4:244-252. [PMID: 26283429 DOI: 10.1021/jz301835j] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Fundamental and basic information about molecules at the solid-liquid interface is limited primarily because most spectroscopic methods are not able to specifically detect the surface buried between two condensed phases. The second-order nonlinear techniques sum frequency generation (SFG) is able to probe the noncentrosymmetric environment between two bulk phases and has been used in many surface studies. In this Perspective, the use of SFG in studies of ionic liquids at the solid-liquid interface will be discussed. Several interfaces are discussed including dielectrics, semiconductors, and metal. SFG results suggest a specific surface model that the ionic liquid structure persists approximately one layer into the bulk liquid and that this is mostly due to the charge neutralization at the surface.
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Affiliation(s)
- Steven Baldelli
- Department of Chemistry, University of Houston, Houston, Texas 77204-5003, United States
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Das S, Bhattacharyya AJ. Time-Temperature Scaling of Conductivity Spectra of Organic Plastic Crystalline Conductors. J Phys Chem Lett 2012; 3:3550-3554. [PMID: 26290986 DOI: 10.1021/jz301742z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Organic plastic crystalline soft matter ion conductors are interesting alternatives to liquid electrolytes in electrochemical storage devices such as lithium-ion batteries. The solvent dynamics plays a major role in determining the ion transport in plastic crystalline ion conductors. We present here an analysis of the frequency-dependent ionic conductivity of succinonitrile-based plastic crystalline ion conductors at varying salt composition (0.005 to 1 M) and temperature (-20 to 60 °C) using time-temperature superposition principle (TTSP). The main motivation of the work has been to establish comprehensive insight into the ion transport mechanism from a single method viz. impedance spectroscopy rather than employing cluster of different characterization methods probing various length and time scales. The TTSP remarkably aids in explicit identification of the extent of the roles of solvent dynamics and ion-ion interactions on the effective conductivity of the orientationally disordered plastic crystalline ion conductors.
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Affiliation(s)
- Supti Das
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Aninda J Bhattacharyya
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
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