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Zhang C, Qu P, Zhou M, Qian L, Bai T, Jin J, Xin B. Ionic Liquids as Promisingly Multi-Functional Participants for Electrocatalyst of Water Splitting: A Review. Molecules 2023; 28:molecules28073051. [PMID: 37049827 PMCID: PMC10095915 DOI: 10.3390/molecules28073051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 03/24/2023] [Accepted: 03/27/2023] [Indexed: 04/01/2023] Open
Abstract
Ionic liquids (ILs), as one of the most concerned functional materials in recent decades, have opened up active perspectives for electrocatalysis. In catalyst preparation, ILs act as characteristic active components besides media and templates. Compared with catalysts obtained using ordinary reagents, IL-derived catalysts have a special structure and catalytic performance due to the influence of IL’s special physicochemical properties and structures. This review mainly describes the use of ILs as modifiers and reaction reagents to prepare electrocatalysts for water splitting. The designability of ILs provides opportunities for the ingenious composition of cations or anions. ILs containing heteroatoms (N, O, S, P, etc.) and transition metal anion (FeCl4−, NiCl3−, etc.) can be used to directly prepare metal phosphides, sulfides, carbides and nitrides, and so forth. The special physicochemical properties and supramolecular structures of ILs can provide growth conditions for catalysts that are different from the normal media environment, inducing special structure and high performance. ILs as heteroatom sources are safe, green and easy to operate compared with traditional heteroatom sources. The strategy for using ILs as reagents is expected to realize 100% atomic transformation of reactants, in line with the concept of green chemistry. This review reflects the discovered work with the best findings from the literature. It will offer readers a deeper understanding on the development of IL-derived electrocatalysts and inspire them to ingeniously design high-performance electrocatalysts for water splitting.
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Affiliation(s)
- Chenyun Zhang
- School of Intelligent Manufacturing, Wuxi Vocational College of Science and Technology, Wuxi 214028, China
| | - Puyu Qu
- School of Intelligent Manufacturing, Wuxi Vocational College of Science and Technology, Wuxi 214028, China
| | - Mei Zhou
- School of Intelligent Manufacturing, Wuxi Vocational College of Science and Technology, Wuxi 214028, China
| | - Lidong Qian
- School of Intelligent Manufacturing, Wuxi Vocational College of Science and Technology, Wuxi 214028, China
| | - Te Bai
- School of Intelligent Manufacturing, Wuxi Vocational College of Science and Technology, Wuxi 214028, China
| | - Jianjiao Jin
- School of Intelligent Manufacturing, Wuxi Vocational College of Science and Technology, Wuxi 214028, China
| | - Bingwei Xin
- College of Chemistry and Chemical Engineering, Dezhou University, Dezhou 253023, China
- Correspondence: ; Tel.: +86-136-8534-5517
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2
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Semavin KD, Chilingarov NS, Dorofeeva OV, Skokan EV, Kalinyuk DA, Yu. Markov V. Evaporation and thermal decomposition of 1-ethyl-3-methylimidazolium chloride. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
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3
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Ionic Liquid/Deep Eutectic Solvent-Mediated Ni-Based Catalysts and Their Application in Water Splitting Electrocatalysis. Catalysts 2022. [DOI: 10.3390/catal12080928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Nickel-based electrocatalysts have been widely used to catalyze electrocatalytic water splitting. In order to obtain high-performance nickel-based electrocatalysts, using ionic liquids and deep eutectic solvents mediated their preparation has received increasing attention. Firstly, ionic liquids and deep eutectic solvents can act as media and templates for the preparation of Ni-based nanomaterials with novel structures and excellent catalytic activity. Secondly, ionic liquids and deep eutectic solvents can be employed as reactants to participate the synthesis of catalysts. Their participation not only increase the catalytic performance, but also simplify the reaction system, improve reproducibility, reduce emissions, and achieve atomic economy. On the basis of the work of our group, this review gives a detailed description of the impressive progress made concerning ionic liquids and deep eutectic solvents in the preparation of nickel-based electrocatalysts according to their roles. We also point out the challenges and opportunities in the field.
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Koutsoukos S, Philippi F, Rauber D, Pugh D, Kay CWM, Welton T. Effect of the cation structure on the properties of homobaric imidazolium ionic liquids. Phys Chem Chem Phys 2022; 24:6453-6468. [PMID: 35244651 DOI: 10.1039/d1cp05169e] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In this work we investigate the structure-property relationships in a series of alkylimidazolium ionic liquids with almost identical molecular weight. Using a combination of theoretical calculations and experimental measurements, we have shown that re-arranging the alkyl side chain or adding functional groups results in quite distinct features in the resultant ILs. The synthesised ILs, although structurally very similar, cover a wide spectrum of properties ranging from highly fluid, glass forming liquids to high melting point crystalline salts. Theoretical ab initio calculations provide insight on minimum energy orientations for the cations, which then are compared to experimental X-ray crystallography measurements to extract information on hydrogen bonding and to verify our understanding of the studied structures. Molecular dynamics simulations of the simplest (core) ionic liquids are used in order to help us interpret our experimental results and understand better why methylation of C2 position of the imidazolium ring results in ILs with such different properties compared to their non-methylated analogues.
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Affiliation(s)
- Spyridon Koutsoukos
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, UK.
| | - Frederik Philippi
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, UK.
| | - Daniel Rauber
- Department of Chemistry, Saarland University, Campus B2.2, 66123, Saarbrücken, Germany
| | - David Pugh
- Department of Chemistry, Britannia House, Kings College London, 7 Trinity Street, London SE1 1DB, UK
| | - Christopher W M Kay
- Department of Chemistry, Saarland University, Campus B2.2, 66123, Saarbrücken, Germany.,London Centre for Nanotechnology, University College London, 17-19 Gordon Street, London WC1H 0AH, UK
| | - Tom Welton
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London W12 0BZ, UK.
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Chen Y, Yu D, Liu Z, Xue Z, Mu T. Thermal, chemical, electrochemical, radiolytic and biological stability of ionic liquids and deep eutectic solvents. NEW J CHEM 2022. [DOI: 10.1039/d2nj03148e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ionic liquids (ILs) and deep eutectic solvents (DESs) are regarded as two kinds of novel solvents with high tunability and they exist in liquid-state for a wide range of temperature....
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Seymour JM, Gousseva E, Large AI, Clarke CJ, Licence P, Fogarty RM, Duncan DA, Ferrer P, Venturini F, Bennett RA, Palgrave RG, Lovelock KRJ. Experimental measurement and prediction of ionic liquid ionisation energies. Phys Chem Chem Phys 2021; 23:20957-20973. [PMID: 34545382 DOI: 10.1039/d1cp02441h] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ionic liquid (IL) valence electronic structure provides key descriptors for understanding and predicting IL properties. The ionisation energies of 60 ILs are measured and the most readily ionised valence state of each IL (the highest occupied molecular orbital, HOMO) is identified using a combination of X-ray photoelectron spectroscopy (XPS) and synchrotron resonant XPS. A structurally diverse range of cations and anions were studied. The cation gave rise to the HOMO for nine of the 60 ILs presented here, meaning it is energetically more favourable to remove an electron from the cation than the anion. The influence of the cation on the anion electronic structure (and vice versa) were established; the electrostatic effects are well understood and demonstrated to be consistently predictable. We used this knowledge to make predictions of both ionisation energy and HOMO identity for a further 516 ILs, providing a very valuable dataset for benchmarking electronic structure calculations and enabling the development of models linking experimental valence electronic structure descriptors to other IL properties, e.g. electrochemical stability. Furthermore, we provide design rules for the prediction of the electronic structure of ILs.
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Affiliation(s)
- Jake M Seymour
- Department of Chemistry, University of Reading, Reading, RG6 6AD, UK.
| | | | - Alexander I Large
- Department of Chemistry, University of Reading, Reading, RG6 6AD, UK. .,Diamond Light Source, Didcot, Oxfordshire, OX11 0DE, UK
| | - Coby J Clarke
- School of Chemistry, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Peter Licence
- School of Chemistry, University of Nottingham, Nottingham, NG7 2RD, UK
| | | | | | - Pilar Ferrer
- Diamond Light Source, Didcot, Oxfordshire, OX11 0DE, UK
| | | | - Roger A Bennett
- Department of Chemistry, University of Reading, Reading, RG6 6AD, UK.
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Polikhronidi NG, Batyrova RG, Dzida M, Abdulagatov IM. Effect of compositional variability due to thermal instability on critical phenomena in n-hexane + IL mixture. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.116368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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8
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Zaitsau DH, Siewert R, Pimerzin AA, Bülow M, Held C, Loor M, Schulz S, Verevkin SP. From volatility to solubility: Thermodynamics of imidazolium-based ionic liquids containing chloride and bromide anions. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2020.114998] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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9
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Araújo JR, de Andrade RB, Batista HJ, Ventura E, do Monte SA. Can a gas phase contact ion pair containing a hydrocarbon carbocation be formed in the ground state? RSC Adv 2021; 11:4221-4230. [PMID: 35424376 PMCID: PMC8694316 DOI: 10.1039/d0ra10523f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 01/11/2021] [Indexed: 11/21/2022] Open
Abstract
So far, no conclusive evidence of a ground-state contact ion-pair containing a hydrocarbon carbocation has been given in the gas phase.
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Affiliation(s)
- José R. Araújo
- Departamento de Química
- CCEN
- Universidade Federal da Paraíba
- João Pessoa
- Brazil
| | | | - Hélcio J. Batista
- Departamento de Química
- Universidade Federal Rural de Pernambuco
- Recife
- Brazil
| | - Elizete Ventura
- Departamento de Química
- CCEN
- Universidade Federal da Paraíba
- João Pessoa
- Brazil
| | - Silmar A. do Monte
- Departamento de Química
- CCEN
- Universidade Federal da Paraíba
- João Pessoa
- Brazil
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10
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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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11
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Mahmood A, Chen S, Chen L, Chen C, Liu D, Weng D, Wang J. Spontaneous propulsion of a water nanodroplet induced by a wettability gradient: a molecular dynamics simulation study. Phys Chem Chem Phys 2020; 22:4805-4814. [PMID: 32068225 DOI: 10.1039/c9cp06718c] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The directional propulsion of liquid droplets at the nanoscale is quite an interesting topic of research in the fields of micro/nano-fluidics, water filtration, precision medicine, and cooling of electronics. In this study, the unidirectional spontaneous transport of a water nanodroplet on a solid surface with a multi-gradient surface (MGS) inspired by natural species is modeled and analyzed using molecular dynamics (MD) simulations. There are three different MGSs considered in this study containing different wedge angles of the hydrophilic region of the solid surface. The MGSs contain two regions: a hydrophilic wedge-shaped region with a constant surface energy parameter equal to 50 meV and a hydrophobic region with a tuned surface energy parameter. The energy parameter of the hydrophobic region is set equal to 1, 5, 10, 20, 30, and 40 meV in order to alter the intensity of the wettability gradient of the two surfaces and its effect on the propulsion of the water nanodroplet is analyzed. Furthermore, three different sizes of water droplets containing 6000, 8000, and 10 000 water molecules are also used in this study and their effect on the transport behavior of the water nanodroplet is also measured. Moreover, two different designs on a solid surface with a continuous wettability gradient are modelled and the impact of solid surface geometry on the transport of the water droplet is calculated by means of mean square displacement (MSD) and average velocity data. In addition, the wedge-shaped surface is found to be more superior to the parallel-shaped surface for the spontaneous propulsion of the water droplet.
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Affiliation(s)
- Awais Mahmood
- State Key Laboratory of Tribology, Tsinghua University, Beijing, 100084, China.
| | - Shuai Chen
- Institute of High Performance Computing, A*STAR, 138632, Singapore
| | - Lei Chen
- State Key Laboratory of Tribology, Tsinghua University, Beijing, 100084, China.
| | - Chaolang Chen
- State Key Laboratory of Tribology, Tsinghua University, Beijing, 100084, China.
| | - Dong Liu
- State Key Laboratory of Tribology, Tsinghua University, Beijing, 100084, China.
| | - Ding Weng
- State Key Laboratory of Tribology, Tsinghua University, Beijing, 100084, China.
| | - Jiadao Wang
- State Key Laboratory of Tribology, Tsinghua University, Beijing, 100084, China.
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12
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Lexow M, Massicot S, Maier F, Steinrück HP. Stability and Exchange Processes in Ionic Liquid/Porphyrin Composite Films on Metal Surfaces. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2019; 123:29708-29721. [PMID: 31867088 PMCID: PMC6913898 DOI: 10.1021/acs.jpcc.9b08531] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Revised: 11/12/2019] [Indexed: 06/10/2023]
Abstract
In light of increasing interest in the development of organic-organic multicomponent heterostructures on metals, this molecular-scale study investigates prototypical composite systems of ultrathin porphyrin and ionic liquid (IL) films on metallic supports under well-defined ultrahigh vacuum conditions. By means of angle-resolved X-ray photoelectron spectroscopy, we investigated the adsorption, stability, and thermal exchange of the resulting films after sequential physical vapor deposition of the free-base porphyrin 5,10,15,20-tetraphenylporphyrin, 2H-TPP, and the IL 1-methyl-3-octylimidazolium hexafluorophosphate, [C8C1Im][PF6], on Ag(111) and Au(111). 2H-TPP shows two-dimensional growth of up to two closed molecular layers on Ag(111) and Au(111) and three-dimensional island growth for thicker films. IL films on top of a monolayer of 2H-TPP exhibit Stranski-Krastanov-like growth and are stable up to 385 K. The 2H-TPP layer leads to destabilization of the IL films, compared to the IL in direct contact with the bare metals, by inhibiting the specific adsorption of the ions on the metal surfaces. When the porphyrin is deposited on top of [C8C1Im][PF6] at low temperature, the 2H-TPP molecules adsorb on top of the IL film at first but replace the IL at the IL/metal interfaces upon heating above 240 K. This exchange process is most likely driven by the higher adsorption energy of 2H-TPP on Ag(111) and Au(111) surfaces, as compared to the IL. The behavior observed on Ag(111) and Au(111) is identical. The results are highly relevant for the stability of porphyrin/IL-based thin film catalyst systems and molecular devices, and more generally, stacked organic multilayer architectures.
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13
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Kinetic stability of imidazolium cations and ionic liquids: A frontier molecular orbital approach. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2018.12.034] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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14
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Lexow M, Heller BSJ, Partl G, Bhuin RG, Maier F, Steinrück HP. Cation Exchange at the Interfaces of Ultrathin Films of Fluorous Ionic Liquids on Ag(111). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:398-405. [PMID: 30540199 PMCID: PMC6377181 DOI: 10.1021/acs.langmuir.8b03517] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
In the context of applications with thin ionic liquid (IL) films on solid supports, we studied the ion distribution within mixed thin IL films by angle-resolved X-ray photoelectron spectroscopy. After the deposition of 1-methyl-3-octylimidazolium hexafluorophosphate, [C8C1Im][PF6], on top of a wetting layer (WL) of 3-methyl-1-(3,3,4,4,4-pentafluorobutyl)imidazolium hexafluorophosphate, [PFBMIm][PF6], on Ag(111) at room temperature (RT), we find a preferential enrichment of the [PFBMIm]+ cation at the IL/vacuum interface. In a similar deposition experiment at 82 K, this cation exchange at the IL/solid interface does not occur. Upon heating the film from 82 K to RT, we observe the replacement of [C8C1Im]+ by [PFBMIm]+ at the IL/vacuum interface between ∼160 and ∼220 K. No further changes in the surface composition were observed between 220 K and RT. Upon further heating the mixed IL film, we find the complete desorption of [PFBMIm][PF6] from the mixed film below 410 K, leaving a WL of pure [C8C1Im][PF6] on Ag(111), which desorbs until 455 K.
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Affiliation(s)
- Matthias Lexow
- Lehrstuhl
für Physikalische Chemie 2, Friedrich-Alexander-Universität
Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
- M.L.: E-mail,
| | - Bettina S. J. Heller
- Lehrstuhl
für Physikalische Chemie 2, Friedrich-Alexander-Universität
Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
| | - Gabriel Partl
- Institut
für Allgemeine, Anorganische und Theoretische Chemie, Leopold-Franzens-Universität Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
| | - Radha G. Bhuin
- 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
| | - Hans-Peter Steinrück
- Lehrstuhl
für Physikalische Chemie 2, Friedrich-Alexander-Universität
Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
- H.-P.S.: E-mail,
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15
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Clarke CJ, Puttick S, Sanderson TJ, Taylor AW, Bourne RA, Lovelock KRJ, Licence P. Thermal stability of dialkylimidazolium tetrafluoroborate and hexafluorophosphate ionic liquids: ex situ bulk heating to complement in situ mass spectrometry. Phys Chem Chem Phys 2018; 20:16786-16800. [PMID: 29888367 DOI: 10.1039/c8cp01090k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Thermal decomposition (TD) products of the ionic liquids (ILs) [CnC1Im][BF4] and [CnC1Im][PF6] ([CnC1Im]+ = 1-alkyl-3-methylimidazolium, [BF4]- = tetrafluoroborate, and [PF6]- = hexafluorophosphate) were prepared, ex situ, by bulk heating experiments in a bespoke setup. The respective products, CnC1(C3N2H2)BF3 and CnC1(C3N2H2)PF5 (1-alkyl-3-methylimidazolium-2-trifluoroborate and 1-alkyl-3-methylimidazolium-2-pentafluorophosphate), were then vaporized and analyzed by direct insertion mass spectrometry (DIMS) in order to identify their characteristic MS signals. During IL DIMS experiments we were subsequently able, in situ, to identify and monitor signals due to both IL vaporization and IL thermal decomposition. These decomposition products have not been observed in situ during previous analytical vaporization studies of similar ILs. The ex situ preparation of TD products is therefore perfectly complimentary to in situ thermal stability measurements. Experimental parameters such as sample surface area to volume ratios are consequently very important for ILs that show competitive vaporization and thermal decomposition. We have explained these experimental factors in terms of Langmuir evaporation and Knudsen effusion-like conditions, allowing us to draw together observations from previous studies to make sense of the literature on IL thermal stability. Hence, the design of experimental setups are crucial and previously overlooked experimental factors.
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Affiliation(s)
- Coby J Clarke
- School of Chemistry, The University of Nottingham, University Park, Nottingham, NG7 2RD, UK
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16
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Dicationic ionic liquid thermal decomposition pathways. Anal Bioanal Chem 2018; 410:4645-4655. [DOI: 10.1007/s00216-018-0878-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 01/04/2018] [Accepted: 01/12/2018] [Indexed: 02/01/2023]
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17
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Lovelock KRJ. Quantifying intermolecular interactions of ionic liquids using cohesive energy densities. ROYAL SOCIETY OPEN SCIENCE 2017; 4:171223. [PMID: 29308254 PMCID: PMC5750021 DOI: 10.1098/rsos.171223] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 10/30/2017] [Indexed: 05/25/2023]
Abstract
For ionic liquids (ILs), both the large number of possible cation + anion combinations and their ionic nature provide a unique challenge for understanding intermolecular interactions. Cohesive energy density, ced, is used to quantify the strength of intermolecular interactions for molecular liquids, and is determined using the enthalpy of vaporization. A critical analysis of the experimental challenges and data to obtain ced for ILs is provided. For ILs there are two methods to judge the strength of intermolecular interactions, due to the presence of multiple constituents in the vapour phase of ILs. Firstly, cedIP, where the ionic vapour constituent is neutral ion pairs, the major constituent of the IL vapour. Secondly, cedC+A, where the ionic vapour constituents are isolated ions. A cedIP dataset is presented for 64 ILs. For the first time an experimental cedC+A, a measure of the strength of the total intermolecular interaction for an IL, is presented. cedC+A is significantly larger for ILs than ced for most molecular liquids, reflecting the need to break all of the relatively strong electrostatic interactions present in ILs. However, the van der Waals interactions contribute significantly to IL volatility due to the very strong electrostatic interaction in the neutral ion pair ionic vapour. An excellent linear correlation is found between cedIP and the inverse of the molecular volume. A good linear correlation is found between IL cedIP and IL Gordon parameter (which are dependent primarily on surface tension). ced values obtained through indirect methods gave similar magnitude values to cedIP. These findings show that cedIP is very important for understanding IL intermolecular interactions, in spite of cedIP not being a measure of the total intermolecular interactions of an IL. In the outlook section, remaining challenges for understanding IL intermolecular interactions are outlined.
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18
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Volpe V, Brunetti B, Gigli G, Lapi A, Vecchio Ciprioti S, Ciccioli A. Toward the Elucidation of the Competing Role of Evaporation and Thermal Decomposition in Ionic Liquids: A Multitechnique Study of the Vaporization Behavior of 1-Butyl-3-methylimidazolium Hexafluorophosphate under Effusion Conditions. J Phys Chem B 2017; 121:10382-10393. [DOI: 10.1021/acs.jpcb.7b08523] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | | | | | - S. Vecchio Ciprioti
- Dipartimento
S.B.A.I., Sapienza Università di Roma, via del Castro
Laurenziano 7, I-00161 Rome, Italy
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19
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Chaban VV, Prezhdo OV. Ionic Vapor Composition in Pyridinium-Based Ionic Liquids. J Phys Chem B 2016; 120:4661-7. [DOI: 10.1021/acs.jpcb.6b03130] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Vitaly V. Chaban
- Instituto
de Ciência e Tecnologia, Universidade Federal de São Paulo, 12231-280, São José dos Campos, SP, Brazil
| | - Oleg V. Prezhdo
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089, United States
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20
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Thomas E, Thomas D, Vijayalakshmi KP, George BK. Mechanistic outlook on thermal degradation of 1,3-dialkyl imidazolium ionic liquids and organoclays. RSC Adv 2016. [DOI: 10.1039/c5ra24907d] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Thermal decomposition of ionic liquid modified sodium montmorillonite clay proceed through an imidazole-2-ylidene (carbene) mediated mechanism with an activation energy of 195.6 kJ mol−1.
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Affiliation(s)
- Eapen Thomas
- Analytical and Spectroscopy Division
- Analytical, Spectroscopy and Ceramics Group
- Propellants, Polymers, Chemicals and Materials Entity
- Vikram Sarabhai Space Centre
- Thiruvananthapuram-695022
| | - Deepthi Thomas
- Analytical and Spectroscopy Division
- Analytical, Spectroscopy and Ceramics Group
- Propellants, Polymers, Chemicals and Materials Entity
- Vikram Sarabhai Space Centre
- Thiruvananthapuram-695022
| | - Kunduchi Periya Vijayalakshmi
- Analytical and Spectroscopy Division
- Analytical, Spectroscopy and Ceramics Group
- Propellants, Polymers, Chemicals and Materials Entity
- Vikram Sarabhai Space Centre
- Thiruvananthapuram-695022
| | - Benny Kattikkanal George
- Analytical and Spectroscopy Division
- Analytical, Spectroscopy and Ceramics Group
- Propellants, Polymers, Chemicals and Materials Entity
- Vikram Sarabhai Space Centre
- Thiruvananthapuram-695022
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21
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Villar-Garcia IJ, Fearn S, Ismail NL, McIntosh AJS, Lovelock KRJ. Fine tuning the ionic liquid–vacuum outer atomic surface using ion mixtures. Chem Commun (Camb) 2015; 51:5367-70. [PMID: 25236677 DOI: 10.1039/c4cc06307d] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ionic liquid–vacuum outer atomic surfaces can be created that are remarkably different from the bulk composition.
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Affiliation(s)
| | - Sarah Fearn
- Department of Materials
- Imperial College
- London
- UK
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22
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Santos AR, Blundell RK, Licence P. XPS of guanidinium ionic liquids: a comparison of charge distribution in nitrogenous cations. Phys Chem Chem Phys 2015; 17:11839-47. [DOI: 10.1039/c5cp01069a] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
We report first X-ray photoelectron spectroscopy (XPS) for a range of functionalised guanidinium based systems that find application in the dissolution of biomolecules. Measured binding energies are compared to those of more common ionic liquid families containing other nitrogen based cations.
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Affiliation(s)
- Ana R. Santos
- School of Chemistry
- The University of Nottingham
- Nottingham NG7 2RD
- UK
| | | | - Peter Licence
- School of Chemistry
- The University of Nottingham
- Nottingham NG7 2RD
- UK
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23
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Kuusik I, Tarkanovskaja M, Kruusma J, Reedo V, Välbe R, Lõhmus A, Kisand V, Lust E, Kukk E, Nõmmiste E. Near threshold photodissociation study of EMIMBF4 vapor. RSC Adv 2015. [DOI: 10.1039/c4ra12775g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Photodissociation of the [EMIM][BF4] ionic liquid vapors following excitation with light in the vacuum ultraviolet region was studied at different liquid temperatures.
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Affiliation(s)
- I. Kuusik
- Institute of Physics
- University of Tartu
- 50411 Tartu
- Estonia
| | | | - J. Kruusma
- Institute of Chemistry
- University of Tartu
- 50411 Tartu
- Estonia
| | - V. Reedo
- Institute of Physics
- University of Tartu
- 50411 Tartu
- Estonia
| | - R. Välbe
- Institute of Physics
- University of Tartu
- 50411 Tartu
- Estonia
| | - A. Lõhmus
- Institute of Physics
- University of Tartu
- 50411 Tartu
- Estonia
| | - V. Kisand
- Institute of Physics
- University of Tartu
- 50411 Tartu
- Estonia
| | - E. Lust
- Institute of Chemistry
- University of Tartu
- 50411 Tartu
- Estonia
| | - E. Kukk
- Dept. of Physics and Astronomy
- University of Turku
- FIN-20014 Turku
- Finland
| | - E. Nõmmiste
- Institute of Physics
- University of Tartu
- 50411 Tartu
- Estonia
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24
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Chambreau SD, Schenk AC, Sheppard AJ, Yandek GR, Vaghjiani GL, Maciejewski J, Koh CJ, Golan A, Leone SR. Thermal Decomposition Mechanisms of Alkylimidazolium Ionic Liquids with Cyano-Functionalized Anions. J Phys Chem A 2014; 118:11119-32. [DOI: 10.1021/jp5095855] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Steven D. Chambreau
- ERC,
Inc., and ‡Propellants Branch, Aerospace Systems Directorate, Air Force Research Laboratory, AFRL/RQRP, Edwards Air Force Base, California 93524, United States
| | | | | | | | | | - John Maciejewski
- Department
of Chemistry, University of Idaho, Moscow, Idaho 83844, United States
| | - Christine J. Koh
- Departments
of Chemistry and Physics, University of California, Berkeley, California 94720, United States
| | - Amir Golan
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Stephen R. Leone
- Departments
of Chemistry and Physics, University of California, Berkeley, California 94720, United States
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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25
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Brunetti B, Ciccioli A, Gigli G, Lapi A, Misceo N, Tanzi L, Vecchio Ciprioti S. Vaporization of the prototypical ionic liquid BMImNTf₂ under equilibrium conditions: a multitechnique study. Phys Chem Chem Phys 2014; 16:15653-61. [PMID: 24958199 DOI: 10.1039/c4cp01673d] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The vaporization behaviour and thermodynamics of the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethyl)sulfonylimide (BMImNTf2) were studied by combining the Knudsen Effusion Mass Loss (KEML) and Knudsen Effusion Mass Spectrometry (KEMS) techniques. KEML studies were carried out in a large temperature range (398-567) K by using effusion orifices with 0.3, 1, and 3 mm diameters. The vapor pressures so measured revealed no kinetically hindered vaporization effects and provided second-law vaporization enthalpies at the mean experimental temperatures in close agreement with literature. By exploiting the large temperature range covered, the heat capacity change associated with vaporization was estimated, resulting in a value of -66.8 J K(-1) mol(-1), much lower than that predicted from calorimetric measurements on the liquid phase and theoretical calculations on the gas phase. The conversion of the high temperature vaporization enthalpy to 298 K was discussed and the value Δ(l)(g)H(m)(298 K) = (128.6 ± 1.3) kJ mol(-1) assessed on the basis of data from literature and present work. Vapor pressure data were also processed by the third-law procedure using different estimations for the auxiliary thermal functions, and a Δ(l)(g)H(m)(298 K) consistent with the assessed value was obtained, although the overall agreement is sensitive to the accuracy of heat capacity data. KEMS measurements were carried out in the lower temperature range (393-467) K and showed that the largely prevailing ion species is BMIm(+), supporting the common view of BMImNTf2 vaporizing as individual, neutral ion pairs also under equilibrium conditions. By monitoring the mass spectrometric signal of this ion as a function of temperature, a second-law Δ(l)(g)H(m)(298 K) of 129.4 ± 7.3 kJ mol(-1) was obtained, well consistent with KEML and literature results. Finally, by combining KEML and KEMS measurements, the electron impact ionization cross section of BMIm(+) was estimated.
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Affiliation(s)
- Bruno Brunetti
- Istituto per lo Studio dei Materiali Nanostrutturati, CNR, c/o Dipartimento di Chimica, Sapienza Università di Roma, P.le A. Moro 5, I-00185, Rome, Italy
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26
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Rietzler F, Piermaier M, Deyko A, Steinrück HP, Maier F. Electrospray ionization deposition of ultrathin ionic liquid films: [C8C1Im]Cl and [C8C1Im][Tf2N] on Au(111). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:1063-1071. [PMID: 24405292 DOI: 10.1021/la404429q] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We introduce a new method for preparing ultrathin ionic liquid (IL) films on surfaces by means of electrospray ionization deposition (ESID) under ultraclean and well-defined ultra-high-vacuum (UHV) conditions. In contrast to physical vapor deposition (PVD) of ILs under UHV, ESID even allows deposition of ILs, which are prone to thermal decomposition. As proof of concept, we first investigated ultrathin [C8C1Im][Tf2N] (=1-methyl-3-octyl imidazolium bis(trifluoromethyl)imide) films on Au(111) by angle-resolved X-ray photoelectron spectroscopy (ARXPS). Films obtained by ESID are found to be virtually identical to films grown by standard PVD. Thereafter, ESID of [C8C1Im]Cl on Au(111) was studied as a first example of an IL that cannot be prepared as ultrathin film otherwise. [C8C1Im]Cl forms a wetting layer with a checkerboard arrangement with the cationic imidazolium ring and the chloride anion adsorbed next to each other on the substrate and the alkyl chain pointing toward vacuum. This arrangement within the wetting layer is similar to that observed for [C8C1Im][Tf2N], albeit with a higher degree of order of the alkyl chains. Further deposition of [C8C1Im]Cl leads to a pronounced island growth on top of the wetting layer, which is independently confirmed by ARXPS and atomic force microscopy. This behavior contrasts the growth behavior found for [C8C1Im][Tf2N], where layer-by-layer growth on top of the wetting layer is observed. The dramatic difference between both ILs is attributed to differences in the cation-anion interactions and in the degree of order in the wetting layer of the two ILs.
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Affiliation(s)
- Florian Rietzler
- Lehrstuhl für Physikalische Chemie II, Friedrich-Alexander-Universität Erlangen-Nürnberg , Egerlandstrasse 3, 91058 Erlangen, Germany
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