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Showing papers on "Ionic liquid published in 2011"


Journal ArticleDOI
04 Nov 2011-Science
TL;DR: An electrocatalytic system that reduces CO2 to carbon monoxide (CO) at overpotentials below 0.2 volt is reported, and the system continued producing CO for at least 7 hours at Faradaic efficiencies greater than 96%.
Abstract: Electroreduction of carbon dioxide (CO(2))--a key component of artificial photosynthesis--has largely been stymied by the impractically high overpotentials necessary to drive the process. We report an electrocatalytic system that reduces CO(2) to carbon monoxide (CO) at overpotentials below 0.2 volt. The system relies on an ionic liquid electrolyte to lower the energy of the (CO(2))(-) intermediate, most likely by complexation, and thereby lower the initial reduction barrier. The silver cathode then catalyzes formation of the final products. Formation of gaseous CO is first observed at an applied voltage of 1.5 volts, just slightly above the minimum (i.e., equilibrium) voltage of 1.33 volts. The system continued producing CO for at least 7 hours at Faradaic efficiencies greater than 96%.

1,226 citations


Journal ArticleDOI
TL;DR: The polymeric ionic liquids (PILs) as mentioned in this paper are a family of functional polymers with particular properties and new applications, such as energy, environment, optoelectronics, analytical chemistry, biotechnology or catalysis.

1,034 citations


Journal ArticleDOI
23 Mar 2011-Polymer
TL;DR: In this paper, a review of the current preparative strategies of poly(ionic liquid)s (PILs) can be found, providing a systematic and actual view on the polymer chemistry behind.

761 citations


Journal ArticleDOI
Liang Zhao1, Yong-Sheng Hu1, Hong Li1, Zhaoxiang Wang1, Liquan Chen1 
TL;DR: In this paper, a uniform nitrogen-doped carbon coating layer is formed on Li4Ti5O12 particles by mixing porous Li4T2O12 powder with an ionic liquid and then treating the mixture at moderate temperature.
Abstract: A uniform nitrogen-doped carbon coating layer is formed on Li4Ti5O12 particles by mixing porous Li4Ti5O12 powder with an ionic liquid and then treating the mixture at moderate temperature. Uniformly coated Li4Ti5O12 is shown to have significantly improved rate capability and cycling performance for Li-ion batteries. This relatively simple approach is versatile and can be extended to modify other electrode materials for electrochemical devices.

751 citations


Journal ArticleDOI
TL;DR: It is demonstrated that the resulting nitrogen-doped carbons show very high catalytic activity, even in the metal-free case in the oxygen reduction reaction (ORR) for fuel cells, and is regarded as a first step toward an all-sustainable fuel cell, avoiding noble metals.
Abstract: Mesoporous nitrogen-doped carbon materials with high surface areas up to 1500 m2 g−1 were conveniently made by the carbonization of nucleobases dissolved in an all-organic ionic liquid (1-ethyl-3-methylimidazolium dicyanamide). Using hard templating with silica nanoparticles, this process yields high-surface-area nitrogen-doped carbon materials with nitrogen contents as high as 12 wt %, narrow mesopore size distribution of ca. 12 nm diameter, and local graphitic carbon structure. It is demonstrated that the resulting nitrogen-doped carbons show very high catalytic activity, even in the metal-free case in the oxygen reduction reaction (ORR) for fuel cells. Specifically, the as-prepared materials exhibit a low onset voltage for ORR in alkaline medium and a high methanol tolerance, compared with those of commercial 20 wt % Pt/C catalyst. We regard this as a first step toward an all-sustainable fuel cell, avoiding noble metals.

745 citations


Journal ArticleDOI
TL;DR: There are a number of technological breakthroughs necessary to reach a mature and cost-effective commercial technology for biomass utilization, and biomass serves as renewable feedstock and could be considered as an alternative source of the chemicals and energy currently derived from petroleum.
Abstract: The reduction of fossil fuels dependence in a framework of shifts in oil prices and geopolitical instability1 is one of the major interests of the current world. It can be achieved by using lignocellulosic biomass. However, there is also growing concern about its overall sustainability, especially regarding land use change, intensified use of agricultural inputs, and possible limitations on food security. Furthermore, the global energy demand is projected to grow over 50% by 2030. This will have an additional impact on the climate and, hence, on our planet. The recent United Nations Framework Convention on Climate Change in Copenhagen, Denmark, has ratified the Kyoto Protocol and is intended to reduce global emissions by at least 20% by 2020 and by 50%-60% by 2050 relative to the emission level in 2006.2 To achieve these ambitious goals in the near future, the next generation of chemicals and fuels from the biorefinery of lignocellulosic biomass has to be used sustainably, since the competition for raw materials between the food and energy industries prevents further (significant) increase of the current first-generation biofuels already on the market. Biomass, especially that which exists in the form of nonedible lignocellulosic materials such as grasses, woods (hard and soft), and crop residues (corn stover, wheat straw, sugar cane, bagasse, etc.), serves as renewable feedstock and could be considered as an alternative source of the chemicals and energy currently derived from petroleum. There are a number of technological breakthroughs necessary to reach a mature and cost-effective commercial technology for biomass utilization. Cost reductions in biological and chemical conversion are to be found in the improvement of individual process steps, far-reaching integration, the development of new efficient methods of carbohydrate conversions by alternative solvents or by robust microbial cell fermentation and by integration of all residues (e.g., spent lignins) and wastewaters into a one-pot process. Lignocellulosic biomass is composed of cellulose, hemicellulose, and lignin. The compositions of these materials vary, and their structures are very complex. Biomass requires many hydrolytic technologies and biological as well as chemical pretreatments to be reduced in size and have its physical structure opened.3 Various methods such as acid hydrolysis, hydrothermal or alkaline treatments, organosolv, solid (super)acids, ionic liquids, or subcritical or supercritical fluids can be employed.4 Carbohydrates constitute up to 75% of the annual production of biomass, estimated at 170 × 109 tons.5 Carbohydrates are an abundant, diverse, and reusable source of carbon. They find many industrial applications in such diverse areas as the chemistry, fermentation, petroleum production, food, paper, and pharmaceutical industries.6 Unfortunately, the * Fax: +351217163636. Telephone: +351210924600ext 4224. E-mail: rafal.lukasik@lneg.pt. † Universidade Nova de Lisboa. ‡ Laboratório Nacional de Energia e Geologia. Małgorzata Ewa Zakrzewska received her two M.Sc. B.Sc. degrees in Environmental Protection Technology and in Biotechnology from the Gdańsk University of Technology, Poland. Currently, at REQUIMTE, Universidade Nova de Lisboa, she has been gaining experience in highpressure work under the supervision of Doctor Rafał Bogel-Łukasik and Professor Manuel Nunes da Ponte. Her research is focused on the application of supercritical CO2 in reaction and extraction. Chem. Rev. 2011, 111, 397–417 397

698 citations


Journal ArticleDOI
25 Jan 2011-ACS Nano
TL;DR: A high-performance supercapacitor incorporating a poly(ionic liquid)-modified reduced graphene oxide (PIL:RG-O) electrode and an ionic liquid (IL) electrolyte with enhanced compatibility with the IL electrolyte, thereby increasing the effective electrode surface area accessible to electrolyte ions.
Abstract: We report a high-performance supercapacitor incorporating a poly(ionic liquid)-modified reduced graphene oxide (PIL:RG-O) electrode and an ionic liquid (IL) electrolyte (specifically, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide or EMIM-NTf2). PIL:RG-O provides enhanced compatibility with the IL electrolyte, thereby increasing the effective electrode surface area accessible to electrolyte ions. The supercapacitor assembled with PIL:RG-O electrode and EMIM-NTf2 electrolyte showed a stable electrochemical response up to 3.5 V operating voltage and was capable of yielding a maximum energy density of 6.5 W·h/kg with a power density of 2.4 kW/kg. These results demonstrate the potential of the PIL:RG-O material as an electrode in high-performance supercapacitors.

657 citations


Journal ArticleDOI
Yao Chen1, Xiong Zhang1, Dacheng Zhang1, Peng Yu1, Yanwei Ma1 
01 Feb 2011-Carbon
TL;DR: In this article, a partially reduced graphene oxide (RGO) has been fabricated using hydrobromic acid, which is a weak reductant, some oxygen functional groups which are relatively stable for electrochemical systems remain in RGO.

631 citations


Journal ArticleDOI
TL;DR: A novel aluminium-ion rechargeable battery comprised of an electrolyte containing AlCl(3) in the ionic liquid, 1-ethyl-3-methylimidazolium chloride, and a V(2)O(5) nano-wire cathode against an aluminium metal anode with very stable electrochemical behaviour is reported.

601 citations


Journal ArticleDOI
TL;DR: In this paper, the advantages and potential of ionic liquids in exploring cleaner catalytic technologies, as compared to traditional catalytic processes, are reviewed with emphasis on four hot fields, viz. biomass conversion, catalytic production of fine chemicals, supported ionic liquid phase catalysis, as well as Friedel-Crafts reactions.

599 citations


Journal ArticleDOI
TL;DR: Basic ionic liquids based on a phosphonium hydroxide derivative can be tuned for CO{sub 2} capture by varying the weak proton donors, which have different pK{sub a} values.
Abstract: Basic ionic liquids (ILs) based on a phosphonium hydroxide derivative can be tuned for CO{sub 2} capture by varying the weak proton donors, which have different pK{sub a} values. The stability, absorption capacity, and absorption enthalpy of the ILs could be easily tuned: the best IL for CO{sub 2} capture has good stability (>300 C), energy saving (ca. 56 kJ mol{sup -1}), and equimolar absorption capability.

Journal ArticleDOI
TL;DR: The physical properties of choline chloride mixtures with glycerol are quantified and it is shown that eutectic mixtures can circumvent some of the difficulties of using Glycerol as a solvent viz. high viscosity and high melting point.

Journal ArticleDOI
TL;DR: The polarities of a wide range of ionic liquids have been determined using the Kamlet-Taft empirical polarity scales α, β and π*, with the dye set Reichardt's Dye, N,N-diethyl-4-nitroaniline and 4-nitrosine to emphasise the importance of recognising the role that the nature of the solute plays in determining these scales.
Abstract: The polarities of a wide range of ionic liquids have been determined using the Kamlet–Taft empirical polarity scales α, β and π*, with the dye set Reichardt's Dye, N,N-diethyl-4-nitroaniline and 4-nitroaniline. These have been compared to measurements of these parameters with different dye sets and to different polarity scales. The results emphasise the importance of recognising the role that the nature of the solute plays in determining these scales. It is particularly noted that polarity scales based upon charged solutes can give very different values for the polarity of ionic liquids compared to those based upon neutral probes. Finally, the effects of commonplace impurities in ionic liquids are reported.

Journal ArticleDOI
TL;DR: In this paper, ground lignocellulosic biomass (Miscanthus giganteus, pine (Pinus sylvestris) and willow (Salix viminalis) was pretreated with ionic liquid-water mixtures of 1-butyl-3methylimidazolium methyl sulfate and 1- butyl- 3methyloridehydrogensulfate hydrogen sulfate.

Journal ArticleDOI
TL;DR: The result for the biomass samples suggests that another factor, likely lignin-carbohydrate complexes, also impacts the rate of cellulose hydrolysis in addition to cellulose crystallinity, and the result for Avicel can be explained by more complete conversion to cellulOSE II upon precipitation after pretreatment at 160 °C.

Journal ArticleDOI
TL;DR: The first pulsed field gradient nuclear magnetic resonance (PFG-NMR) study of DESs found the diffusion mechanism was found to be the same as for ionic liquids with discrete anions, which highlights that the molecular structure of the hydrogen bond donor can greatly affect the mobility of the whole system.
Abstract: Deep Eutectic Solvents (DESs) are a novel class of solvents with potential industrial applications in separation processes, chemical reactions, metal recovery and metal finishing processes such as electrodeposition and electropolishing. Macroscopic physical properties such as viscosity, conductivity, eutectic composition and surface tension are already available for several DESs, but the microscopic transport properties for this class of compounds are not well understood and the literature lacks experimental data that could give a better insight into the understanding of such properties. This paper presents the first pulsed field gradient nuclear magnetic resonance (PFG-NMR) study of DESs. Several choline chloride based DESs were chosen as experimental samples, each of them with a different associated hydrogen bond donor. The molecular equilibrium self-diffusion coefficient of both the choline cation and hydrogen bond donor was probed using a standard stimulated echo PFG-NMR pulse sequence. It is shown that the increasing temperature leads to a weaker interaction between the choline cation and the correspondent hydrogen bond donor. The self-diffusion coefficients of the samples obey an Arrhenius law temperature-dependence, with values of self-diffusivity in the range of [10−10–10−13 m2 s−1]. In addition, the results also highlight that the molecular structure of the hydrogen bond donor can greatly affect the mobility of the whole system. While for ethaline, glyceline and reline the choline cation diffuses slower than the associated hydrogen bond donor, reflecting the trend of molecular size and molecular weight, the opposite behaviour is observed for maline, in which the hydrogen bond donor, i.e. malonic acid, diffuses slower than the choline cation, with self-diffusion coefficients values of the order of 10−13 m2 s−1 at room temperature, which are remarkably low values for a liquid. This is believed to be due to the formation of extensive dimer chains between malonic acid molecules, which restricts the mobility of the whole system at low temperature (<30 °C), with malonic acid and choline chloride having almost identical diffusivity values. Diffusion and viscosity data were combined together to gain insights into the diffusion mechanism, which was found to be the same as for ionic liquids with discrete anions.

Journal ArticleDOI
TL;DR: Their efficiency as antimicrobial agents increased with the hydrophobicity of the amphiphilic cation being the C(14) homologous the most active compounds.

Journal ArticleDOI
TL;DR: In this paper, the use of a commercial ionic liquid as a convenient solvent medium for graphite exfoliation in mild and easy conditions without any chemical modification is presented, and it is noteworthy that, by gravimetric analysis, a graphene concentration as high as 5.33 mg ml−1 was determined.
Abstract: In the present work, the use of a commercial ionic liquid as a convenient solvent medium for graphite exfoliation in mild and easy conditions without any chemical modification is presented. To confirm the presence of few layer graphene, its dispersion, which exhibits Tyndall effect, was characterized by Raman and UV spectroscopies, and atomic force and field emission electron microscopies. It is noteworthy that, by gravimetric analysis, a graphene concentration as high as 5.33 mg ml−1 was determined, which is the highest value reported so far in any solvent.

Journal ArticleDOI
TL;DR: These tunable azole-based ionic liquids with multiple sites with high capacity and excellent reversibility offer significant improvements over commonly used absorbents, indicating the promise for industrial applications in acid gas separation.
Abstract: A novel strategy for SO2 capture through multiple-site absorption in the anion of several azole-based ionic liquids is reported. An extremely high capacity of SO2 (>3.5 mol/mol) and excellent reversibility (28 recycles) were achieved by tuning the interaction between the basic anion and acidic SO2. Spectroscopic investigations and quantum-mechanical calculations showed that such high SO2 capacity originates from the multiple sites of interaction between the anion and SO2. These tunable azole-based ionic liquids with multiple sites offer significant improvements over commonly used absorbents, indicating the promise for industrial applications in acid gas separation.

Journal ArticleDOI
TL;DR: Direct experimental evidence is reported in the form of single-crystal X-ray structures of solid-state products resulting from the reaction of CO2 with acetate ILs, which confirm both the reaction mechanism and the role of complex anion formation.
Abstract: Real chemistry: Spectroscopic and crystallographic analyses confirm the chemical reaction of CO 2 with carbene present in 1,3- dialkylimidazolium acetate ionic liquids and the supporting role of the acetate ion. When CO 2 was bubbled through [C 2mim][OAc], formation of the corresponding imidazolium carboxylate, [C 2mim +-COO -], could be observed. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Journal ArticleDOI
TL;DR: In this article, the authors show that the right combination of the exohedral nanostructured carbon (nanotubes and onions) electrode and a eutectic mixture of ionic liquids can dramatically extend the temperature range of electrical energy storage, thus defying the conventional wisdom that ionic liquid can only be used as electrolytes above room temperature.
Abstract: Relying on redox reactions, most batteries are limited in their ability to operate at very low or very high temperatures. While performance of electrochemical capacitors is less dependent on the temperature, present-day devices still cannot cover the entire range needed for automotive and electronics applications under a variety of environmental conditions. We show that the right combination of the exohedral nanostructured carbon (nanotubes and onions) electrode and a eutectic mixture of ionic liquids can dramatically extend the temperature range of electrical energy storage, thus defying the conventional wisdom that ionic liquids can only be used as electrolytes above room temperature. We demonstrate electrical double layer capacitors able to operate from -50 to 100 °C over a wide voltage window (up to 3.7 V) and at very high charge/discharge rates of up to 20 V/s.

Journal ArticleDOI
TL;DR: In this paper, an overview is given of recent advances in supported membranes based on ionic liquids, including issues such as methods of preparation, transport mechanisms, configurations, stability, fields of application and process intensification using supported ionic liquid membranes.

Journal ArticleDOI
TL;DR: In this paper, the data of liquid density, thermal properties including glass transition temperature, melting point, and decomposition temperature, surface tension, and shear viscosity for imidazolium-based dicationic ionic liquids with the anions of bis(trifluoromethylsulfonyl)amide, bis(pentafluoroethylsulfononyl), tetrafluoroborate, and nitrate.
Abstract: We report the data of liquid density, thermal properties including glass transition temperature, melting point, and decomposition temperature, surface tension, and shear viscosity for imidazolium-based dicationic ionic liquids with the anions of bis(trifluoromethylsulfonyl)amide, bis(pentafluoroethylsulfonyl)amide, tetrafluoroborate, and nitrate. To find the unique and general features of the dicationic ionic liquids, data of their corresponding monocationic ionic liquids are also summarized. The results of the dicationic ionic liquids showed that the density was high; the glass transition temperature and melting point were high, and they were thermally stable. Also the surface tension was large, and the shear viscosity was high in comparison with the reference monocationic ionic liquids. The data of the physical properties including liquid density, surface tension, and shear viscosity of the ionic liquids were also compared with that of alkanediols and alkyl alcohols to find the alkyene-linker and alkyl-...

Journal ArticleDOI
TL;DR: The results that have been obtained indicate that distributed kinetics and dynamical heterogeneity may sometimes, but not always, be influencing factors in ionic liquids.
Abstract: Ionic liquids are subjects of intense current interest within the physical chemistry community. A great deal of progress has been made in just the past five years toward identifying the factors that cause these salts to have low melting points and other useful properties. Supramolecular structure and organization have emerged as important and complicated topics that may be key to understanding how chemical reactions and other processes are affected by ionic liquids. New questions are posed, and an active debate is ongoing regarding the nature of nanoscale ordering in ionic liquids. The topic of reactivity in ionic liquids is still relatively unexplored; however, the results that have been obtained indicate that distributed kinetics and dynamical heterogeneity may sometimes, but not always, be influencing factors.

Journal ArticleDOI
TL;DR: Recent developments in the area of third‐generation ionic liquids that are being used as APIs, with a particular focus on efforts to overcome current hurdles encountered by APIs, are summarized.
Abstract: Ionic liquids (ILs) are ionic compounds that possess a melting temperature below 100 °C. Their physical and chemical properties are attractive for various applications. Several organic materials that are now classified as ionic liquids were described as far back as the mid-19th century. The search for new and different ILs has led to the progressive development and application of three generations of ILs: 1) The focus of the first generation was mainly on their unique intrinsic physical and chemical properties, such as density, viscosity, conductivity, solubility, and high thermal and chemical stability. 2) The second generation of ILs offered the potential to tune some of these physical and chemical properties, allowing the formation of "task-specific ionic liquids" which can have application as lubricants, energetic materials (in the case of selective separation and extraction processes), and as more environmentally friendly (greener) reaction solvents, among others. 3) The third and most recent generation of ILs involve active pharmaceutical ingredients (API), which are being used to produce ILs with biological activity. Herein we summarize recent developments in the area of third-generation ionic liquids that are being used as APIs, with a particular focus on efforts to overcome current hurdles encountered by APIs. We also offer some innovative solutions in new medical treatment and delivery options.

Journal ArticleDOI
TL;DR: In this article, almost 300 papers about ionic liquid-modified electrodes were published and they are reviewed here and they can be classified into three classes: carbon paste electrodes, carbon nanotubes and gel electrodes.

Journal ArticleDOI
18 Apr 2011-Small
TL;DR: The combination of high specific capacitance and outstanding rate capabilities of the OM-CDC materials is unmatched by state-of-the art activated carbons and strictly microporous CDC materials.
Abstract: Ordered mesoporous carbide-derived carbon (OM-CDC) materials produced by nanocasting of ordered mesoporous silica templates are characterized by a bimodal pore size distribution with a high ratio of micropores. The micropores result in outstanding adsorption capacities and the well-defined mesopores facilitate enhanced kinetics in adsorption processes. Here, for the first time, a systematic study is presented, in which the effects of synthesis temperature on the electrochemical performance of these materials in supercapacitors based on a 1 M aqueous solution of sulfuric acid and 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid are reported. Cyclic voltammetry shows the specific capacitance of the OM-CDC materials exceeds 200 F g(-1) in the aqueous electrolyte and 185 F g(-1) in the ionic liquid, when measured in a symmetric configuration in voltage ranges of up to 0.6 and 2 V, respectively. The ordered mesoporous channels in the produced OM-CDC materials serve as ion-highways and allow for very fast ionic transport into the bulk of the OM-CDC particles. At room temperature the enhanced ion transport leads to 75% and 90% of the capacitance retention at current densities in excess of ∼10 A g(-1) in ionic liquid and aqueous electrolytes, respectively. The supercapacitors based on 250-300 μm OM-CDC electrodes demonstrate an operating frequency of up to 7 Hz in aqueous electrolyte. The combination of high specific capacitance and outstanding rate capabilities of the OM-CDC materials is unmatched by state-of-the art activated carbons and strictly microporous CDC materials.

Journal ArticleDOI
TL;DR: Herein a novel class of solvent systems for cellulose is introduced, which contain just a small molar fraction of ionic liquid, and dissolve instantaneously large amounts of cellulose.

PatentDOI
TL;DR: In this article, the authors present compositions and methods of pretreating cellulosic biomass with an ionic liquid and adding a salt containing a kosmotropic anion to facilitate separation of precipitated solids, the aqueous phase, and the ionic fluid phase.
Abstract: The present invention relates to compositions and methods of pretreating cellulosic biomass with an ionic liquid. More specifically it relates to pretreating cellulosic biomass in an ionic liquid and adding a salt containing a kosmotropic anion to facilitate separation of precipitated solids, the aqueous phase, and the ionic liquid phase. The ionic liquid phase may be recycled in a subsequent pretreatment step, and the precipitated solids are enzymatically hydrolyzed to produce smaller oligomers of cellulose, cellbiose, and/or glucose. The kosmotropic anion facilitates phase separation where the aqueous phase contains very low concentrations of the ionic liquid.

Journal ArticleDOI
TL;DR: In this article, a set of thermophysical properties, namely, density, viscosity, and refractive index, as a function of temperature, and isobaric thermal expansivity and heat capacities at a constant temperature, were determined for eight ionic liquids with the 1-ethyl-3-methylimidazolium cation combined with the following anions: acetate, methylphosphonate, methanesulfonate and dimethylphosphate.
Abstract: Among new potential solvents for lignocellulosic materials, ionic liquids (ILs) are attracting considerable attention. Hence, the knowledge of the thermophysical properties of such fluids is essential for the design of related industrial processes. Therefore, in this work, a set of thermophysical properties, namely, density, viscosity, and refractive index, as a function of temperature, and isobaric thermal expansivity and heat capacities at a constant temperature, were determined for eight ionic liquids with the 1-ethyl-3-methylimidazolium cation combined with the following anions: acetate, methylphosphonate, methanesulfonate, trifluoromethanesulfonate, dicyanamide, thiocyanate, tosylate, and dimethylphosphate. Imidazolium-based ILs were chosen since these are the most studied ionic fluids in biomass dissolution approaches, while a large array of anions was investigated because it was already demonstrated that it is the IL anion that mainly governs the dissolution.