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Showing papers on "Ionic liquid published in 2013"


Journal ArticleDOI
TL;DR: Based on the results the novel NADES may be expected as potential green solvents at room temperature in diverse fields of chemistry.

1,614 citations


Journal ArticleDOI
TL;DR: In this article, the application of ionic liquids to the deconstruction and fractionation of lignocellulosic biomass, in a process step that is commonly called pretreatment, is discussed.

1,260 citations


Journal ArticleDOI
22 Mar 2013-Science
TL;DR: It is found that electrolyte gating of epitaxial thin films of VO2 suppresses the metal-to-insulator transition and stabilizes the metallic phase to temperatures below 5 kelvin, even after the ionic liquid is completely removed.
Abstract: Electrolyte gating with ionic liquids is a powerful tool for inducing novel conducting phases in correlated insulators. An archetypal correlated material is vanadium dioxide (VO2), which is insulating only at temperatures below a characteristic phase transition temperature. We show that electrolyte gating of epitaxial thin films of VO2 suppresses the metal-to-insulator transition and stabilizes the metallic phase to temperatures below 5 kelvin, even after the ionic liquid is completely removed. We found that electrolyte gating of VO2 leads not to electrostatically induced carriers but instead to the electric field–induced creation of oxygen vacancies, with consequent migration of oxygen from the oxide film into the ionic liquid. This mechanism should be taken into account in the interpretation of ionic liquid gating experiments.

957 citations


Journal ArticleDOI
TL;DR: In this article, a review summarizes recent advances in the hydrolysis of cellulose by different types of solid acids, such as sulfonated carbonaceous based acids, polymer based acids and magnetic solid acids.

565 citations


Journal ArticleDOI
TL;DR: The potential of NADES for applications involving the extraction of bioactive compounds from natural sources is revealed and it is revealed that the extractability of both polar and less polar metabolites was greater with NADES than conventional solvents.
Abstract: Developing green solvents with low toxicity and cost is an important issue for the biochemical industry. Synthetic ionic liquids and deep eutectic solvents have received considerable attention due to their negligible volatility at room temperature, high solubilization ability, and tunable selectivity. However, the potential toxicity of the synthetic ionic liquids and the solid state at room temperature of most deep eutectic solvents hamper their application as extraction solvents. In this study, a wide range of recently discovered natural ionic liquids and deep eutectic solvents (NADES) composed of natural compounds were investigated for the extraction of phenolic compounds of diverse polarity. Safflower was selected as a case study because its aromatic pigments cover a wide range of polarities. Many advantageous features of NADES (such as their sustainability, biodegradability combined with acceptable pharmaceutical toxicity profiles, and their high solubilization power of both polar and nonpolar compounds) suggest their potential as green solvents for extraction. Experiments with different NADES and multivariate data analysis demonstrated that the extractability of both polar and less polar metabolites was greater with NADES than conventional solvents. The water content in NADES proved to have the biggest effect on the yield of phenolic compounds. Most major phenolic compounds were recovered from NADES with a yield between 75% and 97%. This study reveals the potential of NADES for applications involving the extraction of bioactive compounds from natural sources.

484 citations


Journal ArticleDOI
TL;DR: Ionic liquids are room-temperature molten salts that possess unique properties, such as negligible vapour pressure, good thermal stability and non-flammability, together with high ionic conductivity and a wide window of electrochemical stability as discussed by the authors.
Abstract: Ionic liquids (ILs) are room-temperature molten salts that possess unique properties, such as negligible vapour pressure, good thermal stability and non-flammability, together with high ionic conductivity and a wide window of electrochemical stability. Combining ILs with polymer electrolytes offers the prospect of new applications e.g. in batteries and fuel cells, where they surpass the performance of conventional media such as organic solvents (in batteries) or water (in polymer electrolyte membrane fuel cells), giving advantages in terms of improved safety and a higher operating temperature range. However, the most important challenge is how to immobilize ILs in polymer matrices while retaining their sought-after properties. Our goal in this review is to survey the recent developments and issues within IL research in polymer electrolytes.

428 citations


Journal ArticleDOI
TL;DR: A facile method to fabricate high-surface area functional carbons via convenient "salt templating" is presented and nitrogen- as well as nitrogen-/boron-co-doped carbons were synthesized using ionic liquids and eutectics as porogen.
Abstract: A facile method to fabricate high-surface area functional carbons via convenient "salt templating" is presented. Exemplarily, nitrogen- as well as nitrogen-/boron-co-doped carbons were synthesized using ionic liquids as precursors and eutectics as porogen. The porogen is easily removable with water and the porosities can be adjusted from micro- to mesoporous depending on the salt nature and amount.

420 citations


Journal ArticleDOI
TL;DR: In this paper, simple solvate ionic liquids, glyme-Li salt molten complexes, are presented as excellent electrolyte candidates because they greatly suppress the dissolution of lithium polysulfides, which leads to the stable operation of Li-S battery over more than 400 cycles with discharge capacities higher than 700 mAh g-sulfur−1 and with coulombic efficiencies higher than 98% throughout the cycles.
Abstract: Innovation in the design of electrolyte materials is crucial for realizing next-generation electrochemical energy storage devices such as Li–S batteries. The theoretical capacity of the S cathode is 10 times higher than that of conventional cathode materials used in current Li–ion batteries. However, Li–S batteries suffer from the dissolution of lithium polysulfides, which are formed by the redox reaction at the S cathode. Herein, we present simple solvate ionic liquids, glyme–Li salt molten complexes, as excellent electrolyte candidates because they greatly suppress the dissolution of lithium polysulfides. The molten complexes do not readily dissolve other ionic solutes, which leads to the stable operation of the Li–S battery over more than 400 cycles with discharge capacities higher than 700 mAh g-sulfur−1 and with coulombic efficiencies higher than 98% throughout the cycles. Such high performance has not been realized to the best of our knowledge. Furthermore, the addition of a nonflammable fluorinated solvent, which does not break the solvate structure of the glyme–Li salt molten complexes, greatly enhances the power density of the Li–S battery. The strategic design of electrolyte properties provides opportunities for the development of new electrochemical devices with many different electrode materials.

392 citations


Journal ArticleDOI
TL;DR: In this paper, a series of deep eutectic solvents (DESs) were designed and synthesized for the desulfurization of fuels, and the results showed that the above DESs can be used for the deep extraction of fuels successfully.

373 citations


Journal ArticleDOI
TL;DR: This review summarizes the preparation of ionic liquids and deep eutectic solvents with natural product components and recent progress in their applications to the extraction and analysis of natural products as well as the recovery of extracted compounds from their extracts.
Abstract: Mixtures of solid chemicals may become liquid under certain conditions. These liquids are characterized by the formation of strong ionic (ionic liquids) or hydrogen bonds (deep eutectic solvents). Due to their extremely low vapor pressure, they are now widely used in polymer chemistry and synthetic organic chemistry, yet little attention has been paid to their use as extraction solvents of natural products. This review summarizes the preparation of ionic liquids and deep eutectic solvents with natural product components and recent progress in their applications to the extraction and analysis of natural products as well as the recovery of extracted compounds from their extracts. Additionally, various factors affecting extraction features of ionic liquids and deep eutectic solvents, as well as potential useful technologies including microwave and ultrasound to increase the extraction efficiency, are discussed.

362 citations


Journal ArticleDOI
TL;DR: The results indicate that ionic liquids screen charged surfaces through the formation of both bound (Stern) and diffuse electric double layers, where the diffuse double layer is comprised of effectively dissociated ionic liquid ions.
Abstract: We combine direct surface force measurements with thermodynamic arguments to demonstrate that pure ionic liquids are expected to behave as dilute weak electrolyte solutions, with typical effective dissociated ion concentrations of less than 0.1% at room temperature. We performed equilibrium force–distance measurements across the common ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][NTf2]) using a surface forces apparatus with in situ electrochemical control and quantitatively modeled these measurements using the van der Waals and electrostatic double-layer forces of the Derjaguin–Landau–Verwey–Overbeek theory with an additive repulsive steric (entropic) ion–surface binding force. Our results indicate that ionic liquids screen charged surfaces through the formation of both bound (Stern) and diffuse electric double layers, where the diffuse double layer is comprised of effectively dissociated ionic liquid ions. Additionally, we used the energetics of thermally dissociating ions in a dielectric medium to quantitatively predict the equilibrium for the effective dissociation reaction of [C4mim][NTf2] ions, in excellent agreement with the measured Debye length. Our results clearly demonstrate that, outside of the bound double layer, most of the ions in [C4mim][NTf2] are not effectively dissociated and thus do not contribute to electrostatic screening. We also provide a general, molecular-scale framework for designing ionic liquids with significantly increased dissociated charge densities via judiciously balancing ion pair interactions with bulk dielectric properties. Our results clear up several inconsistencies that have hampered scientific progress in this important area and guide the rational design of unique, high–free-ion density ionic liquids and ionic liquid blends.

Journal ArticleDOI
TL;DR: In this paper, 70 DESs were synthesized successfully based on glycerol (Gly) as the HBD with different phosphonium and ammonium salts, namely methyl triphenyl phosphono-bromide (MTPB), benzyl triphenyi-triphenyl-phosphonium bromide(BTPC), allyl triphethenyl phono-phonium (ATPB), choline chloride (ChCl), N,N-diethylethanolammonium chloride (DAC), and tetra-

Journal ArticleDOI
TL;DR: Deep eutectic solvents were used to extract flavonoids (myricetin and amentoflavone), which are well known and widely used antioxidants, to extend their applications and highlight their potential for the extraction and determination of a range of bioactive compounds or drugs.

Journal ArticleDOI
Xi Yang1, Fan Zhang1, Long Zhang1, Tengfei Zhang1, Yi Huang1, Yongsheng Chen1 
TL;DR: In this paper, a high performance graphene oxide-doped ion gel (P(VDF-HFP)-EMIMBF4-GO gel) is prepared by exploiting copolymer (poly(vinylidene fluoride-hexafluoro propylene), P(HFP)) as the polymer matrix, ionic liquid (1-ethyl-3-methylimidazolium tetrafluoroborate, EMIMBF 4) as the supporting electrolyte, and GO as the ionic conducting promoter.
Abstract: A high-performance graphene oxide (GO)-doped ion gel (P(VDF-HFP)-EMIMBF4-GO gel) is prepared by exploiting copolymer (poly(vinylidene fluoride-hexafluoro propylene), P(VDF-HFP)) as the polymer matrix, ionic liquid (1-ethyl-3-methylimidazolium tetrafluoroborate, EMIMBF4) as the supporting electrolyte, and GO as the ionic conducting promoter. This GO-doped ion gel demonstrates significantly improved ionic conductivity compared with that of pure ion gel without the addition of GO, due to the homogeneously distributed GO as a 3D network throughout the GO-doped ion gel by acting like a ion “highway” to facilitate the ion transport. With the incorporation of only a small amount of GO (1 wt%) in ion gel, there has been a dramatic improvement in ionic conductivity of about 260% compared with that of pure ion gel. In addition, the all-solid-state supercapacitor is fabricated and measured at room temperature using the GO-doped ion gel as gel polymer electrolyte, which demonstrates more superior electrochemical performance than the all-solid-state supercapacitor with pure ion gel and the conventional supercapacitor with neat EMIMBF4, in the aspect of smaller internal resistance, higher capacitance performance, and better cycle stability. These excellent performances are due to the high ionic conductivity, excellent compatibility with carbon electrodes, and long-term stability of the GO-doped ion gel.

Journal ArticleDOI
TL;DR: This review describes recent developments in the field-effect transistors (FETs) with gate dielectrics of ionic liquids, which have attracted much attention due to their wide electrochemical windows, low vapor pressures, and high chemical and physical stability.
Abstract: Charge carrier control is a key issue in the development of electronic functions of semiconductive materials. Beyond the simple enhancement of conductivity, high charge carrier accumulation can realize various phenomena, such as chemical reaction, phase transition, magnetic ordering, and superconductivity. Electric double layers (EDLs), formed at solid-electrolyte interfaces, induce extremely large electric fields. This results in a high charge carrier accumulation in the solid, much more effectively than solid dielectric materials. In the present review, we describe recent developments in the field-effect transistors (FETs) with gate dielectrics of ionic liquids, which have attracted much attention due to their wide electrochemical windows, low vapor pressures, and high chemical and physical stability. We explain the capacitance effects of ionic liquids, and describe the various combinations of ionic liquids and organic and inorganic semiconductors that are used to achieve such effects as high transistor performance, insulator-metal transitions, superconductivity, and ferromagnetism, in addition to the applications of the ionic-liquid EDL-FETs in logic devices. We discuss the factors controlling the mobility and threshold voltage in these types of FETs, and show the ionic liquid dependence of the transistor performance.

Journal ArticleDOI
TL;DR: The ability of ionic liquids (ILs) to support amphiphile self-assembly into a range of mesophase structures has been established as a widespread phenomenon as mentioned in this paper, and the vast majority of ILs have supported some lyotropic liquid crystal phase formation.
Abstract: The ability of ionic liquids (ILs) to support amphiphile self-assembly into a range of mesophase structures has been established as a widespread phenomenon. From the ILs evaluated as self-assembly media, the vast majority have supported some lyotropic liquid crystal phase formation. Many neat ionic liquids have been shown to segregate into polar and non-polar domains to form a nanostructured liquid. A very strong correlation between the nanostructure of the ionic liquid and its characteristics as an amphiphile self-assembly solvent has been found. In this review we discuss ionic liquids as amphiphile self-assembly media, and identify trends that can be used to distinguish which ionic liquids are likely to have good promotion properties as self-assembly media. In particular these trends focus on the nanostructure of neat ionic liquids, their solvent cohesive energy density, and the related solvophobic effect. We forecast that many more ILs will be identified as amphiphile self-assembly solvents in the future.

Journal ArticleDOI
TL;DR: In this paper, a carbon-ionic liquid system with high capacitance of up to 180 F/g and wide electrochemical window (up to 3.5 V) over a wide temperature range from −50 °C to 80 °C.

Journal ArticleDOI
TL;DR: An environmentally friendly process for the separation of the transition metals copper, cobalt, iron, manganese and zinc from rare earths by solvent extraction with the ionic liquid trihexyl(tetradecyl)phosphonium chloride has been developed as discussed by the authors.

BookDOI
16 Apr 2013
TL;DR: Green Solvents - Legislation and Certification "Solvent-free" Chemistry Water Supercritical Fluids Renewable solvents and Other 'Green' VOCs Room-Temperature Ionic Liquids and Eutectic Mixtures Liquid Polymers Tunable and Switchable Solvent Systems Industrial Applications of Green SolvENTS Education and Outreach as discussed by the authors.
Abstract: Introduction Green Solvents - Legislation and Certification 'Solvent-Free' Chemistry Water Supercritical Fluids Renewable Solvents and Other 'Green' VOCs Room-Temperature Ionic Liquids and Eutectic Mixtures Fluorous Solvents and Related Systems Liquid Polymers Tunable and Switchable Solvent Systems Industrial Applications of Green Solvents Education and Outreach.

Journal ArticleDOI
TL;DR: In this paper, the recent progress in the conversion of glucose and cellulose in water or ionic liquids (ILs) by oxidation, hydrogenation, and dehydration reactions is discussed.

Journal ArticleDOI
TL;DR: In this paper, a variety of binary mixtures of aprotic ionic liquids (ILs) and lithium salts were thoroughly studied as electrolytes for rechargeable lithium-sulfur (Li-S) batteries.
Abstract: A variety of binary mixtures of aprotic ionic liquids (ILs) and lithium salts were thoroughly studied as electrolytes for rechargeable lithium–sulfur (Li–S) batteries. The saturation solubility of sulfur and lithium polysulfides (Li2Sm), the active materials in the Li–S battery, in the electrolytes was quantitatively determined, and the performance of the Li–S battery using the electrolytes was also investigated. Although the solubility of nonionic sulfur was low in all of the electrolytes evaluated, the solubility of Li2Sm in the IL-based electrolyte was strongly dependent on the anionic structure, and the difference in the solubility could be rationalized in terms of the donor ability of the IL solvent. Dissolution of Li2Sm in the ILs with strong donor ability was comparable to that achieved with typical organic electrolytes; the strongly donating IL electrolyte did not prevent redox shuttle reaction in the Li–S cells. The battery performance was also influenced by unfavorable side reactions of the anio...

Journal ArticleDOI
TL;DR: In this article, the most recent analytical developments aimed at employing Ionic liquids (ILs) in dispersive liquid-liquid microextraction (DLLME) are summarized.
Abstract: In this review, we summarize the most recent analytical developments aimed at employing Ionic liquids (ILs) in dispersive liquid-liquid microextraction (DLLME). Four main operation modes can be distinguished: (1) conventional IL-DLLME; (2) temperature-controlled IL-DLLME; (3a) ultrasound-assisted, (3b) microwave-assisted or (3c) vortex-assisted IL-DLLME; and, (4) in-situ IL-DLLME. In these modes, the dispersive solvent can be an organic solvent, a surfactant, or a hydrophilic IL. In some cases, a dispersive solvent is not even necessary. We discuss practical applications of IL-DLLME to determine metals and organic compounds in a variety of samples.

Journal ArticleDOI
TL;DR: Several areas of bio-applications, including antitumour, antimicrobial, antioxidant and bioengineering applications, will be presented and discussed in this review of imidazolium salts.
Abstract: Imidazolium salts, distinct from their parent imidazoles, are made up of a discrete cation and anion pair, and have found widespread utility as ionic liquids. A lesser known function of such imidazolium salts includes the application of these salts in biological systems, and several areas of bio-applications, including antitumour, antimicrobial, antioxidant and bioengineering applications, will be presented and discussed in this review. The wide-ranging applications and versatility of these imidazolium salts stem from the ease of their structural variation, in which properties such as amphiphilicity, lipophilicity and solubility can be tuned.

Journal ArticleDOI
TL;DR: Deep eutectic solvents (DESs) as mentioned in this paper are a class of high-dimensional liquid medium with similar properties to ionic liquids but with additional advantages regarding cost, environmental impact, and synthesis.
Abstract: In recent years, a novel medium with similar properties to ionic liquids but with additional advantages regarding cost, environmental impact, and synthesis has been developed: deep eutectic solvents (DESs). These solvents result from the association between an organic salt (ammonium or phosphonium) with a hydrogen-bond donor such as alcohols, acids, or amides. To date, the availability of green, inexpensive and easy to handle solvents is almost non-existent. Therefore, DESs currently arouse growing interest in many research fields. This review deals with the major applications of this new family of solvents with a particular focus on lipase-catalyzed reactions such as hydrolysis, aminolysis, or alcoholysis.

Journal ArticleDOI
TL;DR: In this article, the power generation characteristics of thermoelectrochemical cells using a series of ionic liquids and MPN with the CoII/III(bpy)3(NTf2)2/3 couple are described.
Abstract: Manipulation of the cobalt(II/III) tris(bipyridyl) redox couple through anion exchange has improved its solubility in ionic liquids and 3-methoxypropionitrile (MPN). This has allowed the preparation of electrolytes with high Seebeck coefficients, Se = 1.5–2.2 mV K−1, and thereby excellent prospects for thermal harvesting. The unique physical properties of ionic liquids offer ideal characteristics for their use as electrolytes in thermoelectrochemical cells, particularly for applications involving thermal energy available at temperatures in the 100–200 °C range. The power generation characteristics of thermoelectrochemical cells using a series of ionic liquids and MPN with the CoII/III(bpy)3(NTf2)2/3 couple are described. Power densities reached >0.5 W m−2 in unoptimized devices, operating with a 130 °C hot side. The high Seebeck coefficient appears to have its origins in the high-to-low spin transition upon electron transfer in this cobalt complex.

Journal ArticleDOI
TL;DR: This tutorial review presents an overview of the development of organic molecules as mediators and catalysts for CO(2) reduction, and shows that reactions mediated or catalyzed by these organic molecules can be competitive compared to their metal-catalyzed counterparts, both in terms of product selectivity and energy efficiency.
Abstract: Reduction of CO2 by electrochemical and photoelectrochemical methods to produce carbon-rich fuels is a heavily pursued research theme. Most of the current efforts are focused on the development of transition-metal-based catalysts. In this tutorial review, we present an overview of the development of organic molecules as mediators and catalysts for CO2 reduction. Four classes of organic molecules are discussed: tetraalkylammonium salts, aromatic esters and nitriles, ionic liquids, and pyridinium derivatives. It is shown that reactions mediated or catalyzed by these organic molecules can be competitive compared to their metal-catalyzed counterparts, both in terms of product selectivity and energy efficiency.

Journal ArticleDOI
Fan Yang1, Fukiko Kubota1, Yuzo Baba1, Noriho Kamiya1, Masahiro Goto1 
TL;DR: An effective recovery of the rare earth metals, Y, Eu, La and Ce, from the metal impurities, Fe, Al and Zn, was achieved from the acidic leach solution of phosphor powders using an ionic liquid containing DODGAA as novel extractant system.

Journal ArticleDOI
TL;DR: The size, direction, strength, and distribution of hydrogen bonds in several protic ionic liquids (PILs) has been elucidated using neutron diffraction and computer simulation.
Abstract: The size, direction, strength, and distribution of hydrogen bonds in several protic ionic liquids (PILs) has been elucidated using neutron diffraction and computer simulation. There is significant variation in PIL hydrogen bond interactions ranging from short and linear to long and bi-/trifurcated. The nature of the PIL's hydrogen bonds reflects its macroscopic properties.

Journal ArticleDOI
TL;DR: The low thermal stability of 1-ethyl-3-methylimidazolium acetate has important implications for biomass experiments employing this ionic liquid, and the activation barriers for the S(N)2 nucleophilic substitution mechanisms are in good agreement with the experimentally determined values.
Abstract: The thermal stability of a series of dialkylimidazolium carboxylate ionic liquids has been investigated using a broad range of experimental and computational techniques. Ionic liquids incorporating fluoroalkyl carboxylate anions were found to have profoundly differing thermal stabilities and decomposition mechanisms compared with their non-fluorinated analogues. 1-Ethyl-3-methylimidazolium acetate was observed to largely decompose via an SN2 nucleophilic substitution reaction when under inert gas conditions, predominantly at the imidazolium methyl substituent. The Arrhenius equations for thermal decomposition of 1-ethyl-3-methylimidazolium acetate, and the C2-methylated analogue 1-ethyl-2,3-dimethylimidazolium acetate, were determined from isothermal Thermogravimetric Analysis experiments. The low thermal stability of 1-ethyl-3-methylimidazolium acetate has important implications for biomass experiments employing this ionic liquid. For these two ionic liquids, ion pair and transition state structures were optimised using Density Functional Theory. The activation barriers for the SN2 nucleophilic substitution mechanisms are in good agreement with the experimentally determined values.

Journal ArticleDOI
TL;DR: In this article, a hierarchical porous carbon with variable pore sizes at multi-length-scale, a nitrogen and boron co-doped and local graphitized framework, and high mechanical strength were synthesized through the self-assembly of poly(benzoxazine-co-resol) with ionic liquid C16mimBF4 and a carbonization process.
Abstract: Hierarchically porous carbons with variable pore sizes at multi-length-scale, a nitrogen and boron co-doped and local graphitized framework, and high mechanical strength were synthesized through the self-assembly of poly(benzoxazine-co-resol) with ionic liquid C16mimBF4 and a carbonization process. In this synthesis, the ionic liquid acts both as a structure directing agent and a heteroatom precursor. The obtained porous carbons have a specific surface area lower than 376 m2 g−1 and thus a high skeleton density. With such heteroatom doped skeleton structures and fully interconnected macropores, mesopores and micropores, the hierarchically porous carbon shows outstanding electrochemical performance, e.g. a superior high gravimetric capacitance (Cg) of 247 F g−1, an interfacial capacitance (CS) of 66 μF cm−2 (calculated based on the discharge curve with a constant current density of 0.5 A g−1), whilst a high volumetric capacitance (Cv) of 101 F cm−3 compared to those reported in the literature. Cycling stability tests indicate that the carbon exhibits a capacitance retention of ∼96.2% after 4000 charge–discharge cycles, strongly reflecting an excellent long-term cyclability of the electrode. Due to its unique skeleton structure and high conductivity, such hierarchically porous carbon shows promise as an electrode material for supercapacitors.