Tetrafluoroborate Ionic Liquid Research Articles

Effect of 1-Ethyl-3-methylimidazolium Tetrafluoroborate and Acetate Ionic Liquids on Stability and Amyloid Aggregation of Lysozyme.

Amyloid fibrils draw attention as potential novel biomaterials due to their high stability, strength, elasticity or resistance against degradation. Therefore, the controlled and fast fibrillization process is of great interest, which raises the demand for effective tools capable of regulating amyloid fibrillization. Ionic liquids (ILs) were identified as effective modulators of amyloid aggregation. The present work is focused on the study of the effect of 1-ethyl-3-methyl imidazolium-based ILs with kosmotropic anion acetate (EMIM-ac) and chaotropic cation tetrafluoroborate (EMIM-BF4) on the kinetics of lysozyme amyloid aggregation and morphology of formed fibrils using fluorescence and CD spectroscopy, differential scanning calorimetry, AFM with statistical image analysis and docking calculations. We have found that both ILs decrease the thermal stability of lysozyme and significantly accelerate amyloid fibrillization in a dose-dependent manner at concentrations of 0.5%, 1% and 5% (v/v) in conditions and time-frames when no fibrils are formed in ILs-free solvent. The effect of EMIM-BF4 is more prominent than EMIM-ac due to the different specific interactions of the anionic part with the protein surface. Although both ILs induced formation of amyloid fibrils with typical needle-like morphology, a higher variability of fibril morphology consisting of a different number of intertwining protofilaments was identified for EMIM-BF4.

Ionic liquid/TiO2 nanoparticles doped with non-expensive metals: new active catalyst for phenol photodegradation.

TiO2 nanoparticles were synthesized using 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMI·BF4) ionic liquid and doped with non-expensive metals Cu2+ and Fe3+ by the sol–gel method. The new generated photocatalysts had their morphological, textural and structural characteristics analysed by scanning electron microscopy and dispersive X-ray spectroscopy (SEM/EDS), transmission electron microscopy (TEM), Brunauer–Emmett–Teller analysis (BET), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and diffuse reflectance spectroscopy (DRS). The results showed two phases by XRD analysis, anatase (majority) and rutile (minority). The SEM micrographs exposed spherical TiO2 NPs/BMI·BF4 IL and compact layers for Cu2+ and Fe3+-doped TiO2 NPs in BMI·BF4 IL, the EDX confirmed only the presence of Ti, O, Fe and Cu. The BET and BJH analyses exhibited high porous TiO2 NPs/BMI·BF4 IL. The BET and BJH analyses confirmed that the pore diameter of mesoporous materials was between 12 and 16 nm with similar values for surface area (55–63 m2 g−1). The TEM images exhibited spherical shape nanoparticles with mean diameter of 20–22 nm. The DRS analysis and Tauc equation were applied to estimate the optical energy band gap of the photocatalysts. The energy band gap values of 3.1 eV, 3.32 eV, and 2.78 eV were obtained for TiO2 NPs/BMI·BF4 IL, 1% Fe3+-doped TiO2 NPs/BMI·BF4 IL and 1% Cu2+-doped TiO2 NPs/BMI·BF4 IL, respectively. Phenol photodegradation was realized using Cu2+ and Fe3+-doped TiO2 NPs/BMI·BF4 IL under UV/visible irradiation and quantified by HPLC-FLD. The phenol photodegradation was investigated by different concentrations of metal-doped TiO2 NPs/BMI·BF4 IL. The new active photocatalysts 1% Cu2+-doped TiO2 NPs and 1% Fe3+-doped TiO2 NPs/BMI·BF4 IL exhibited high catalytic activity (99.9% and 96.8%, respectively). The photocatalysts 1% Cu2+ and 1% Fe3+-doped TiO2 NPs/BMI·BF4 IL were also evaluated using industrial wastewater from the tobacco industry. The results showed 56.7% phenol photodegradation, due to the complexity of the tobacco matrix wastewater.

Insight into the Supercapacitive Behavior of Activated Hollow Porous Carbon Spheres in Different Electrolytes

Supercapacitive behaviors of the porous carbon electrode principally depend on the properties of electrolyte. In this paper, activated hollow porous carbon spheres (AHPCSs) with large specific areas were prepared by the hydrothermal method and subsequent one-step KOH activation treatment. The electrochemical performances and supercapacitive characteristics of the AHPCS supercapacitors were evaluated in 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) ionic liquid electrolyte, 1 mol L–1 LiPF6 organic electrolyte, and 6 mol L–1 KOH aqueous electrolyte. It has been found that the supercapacitors with AHPCS electrode have definitely good supercapacitive behaviors in the three electrolytes. Especially, the AHPCS supercapacitor in the EMIMBF4 ionic liquid electrolyte that has a wide operating voltage of 0–3.0 V exhibits an excellent rate performance with capacitance retention of 72.3% from 0.5 to 10 A g–1 and a good cycle performance with a high capacitance retention of 94.2% after 4000 consecutive cycles. Moreover, it obtains a high energy density of 80.5 Wh kg–1 at 750 W kg–1, which transcends most of the currently reported carbon-based supercapacitors. Therefore, the supercapacitors with EMIMBF4 ionic liquid as electrolyte and AHPCSs as active electrode materials show tremendous potential in terms of boosting comprehensively electrochemical performance.

A comprehensive multidisciplinary investigation on CO2 capture from diesel engine.

Climate change and global warming are the visible consequences of the increased amount of carbon dioxide (CO2) in the atmosphere. Among the various sources of anthropogenic CO2 emission, the diesel engine has a significant contribution. The development of a reliable system to efficiently minimize CO2 emissions from diesel engines to the safest level is lacking in the open literature. Therefore, a comprehensive multidisciplinary approach has been applied in this paper to investigate the efficacy of the post-combustion carbon capture (PCC) process for the diesel engine. The experiments have been performed on the exhaust of a direct injection diesel engine at five different brake powers with blends of aqueous ammonia (AQ_NH3), monoethanolamine (MEA), N,N-dimethylethanolamine (DMEA), and 1-ethyl-3-methylimidazolium tetrafluoroborate (C2mim BF4) ionic liquid (IL) as an absorbent for CO2 capture. The reaction mechanism of these absorbent with CO2 are also studied by the geometrical, energetical, MESP, frontier molecular orbitals, and NBO analysis using the first-principles density functional theory (DFT) calculations. The maximum CO2 absorption efficiency of almost 97% was achieved for the blend consisting of 67% of AQ_NH3 and 33% of MEA. Moreover, AQ_MEA and blend of AQ_NH3, DMEA, and C2mim BF4 ionic liquid showed 96% and 94% CO2 absorption efficiency, respectively.

Effect of acetonitrile on the interface structure of Au (1 0 0)/1-butyl-3-methyl tetrafluoroborate ionic liquid determined by a molecular dynamics simulation

The effect of acetonitrile on the interface structure of Au (100)/1-butyl-3-methyl tetrafluoroborate ionic liquid was determined by a molecular dynamics simulation. The effects of acetonitrile on the bulk properties of [Bmim]BF4, the molecular orientation of [Bmim]BF4 at the interface, the number density, the mass density, and the charge density were determined. It was found that as the concentration of acetonitrile increases, the viscosity of the ionic liquid decreases and the conductivity increases. With the addition of acetonitrile, due to the strong interaction between [Bmim]+ cations and the plate, acetonitrile was found to enter the inner layer, causing the orientation angle of the imidazole ring to incline.

Imidazole-Based Ionic Liquids with BF4 as the Counterion Perform Outstanding Abilities in Both Inhibiting Clay Swelling and Lowing Water Cluster Size.

Promoting fluid transportation in porous media has important applications in energy, pedology, bioscience, etc. For this purpose, one effective way is to prevent swelling through surface modification; however, it is far from enough in real cases, such as ultra-low permeability reservoirs and tight oils. In this study, we considered the comprehensive effects of inhibiting clay swelling, flocculation performance, reducing water clusters and interfacial tension and developed a series of imidazole-based tetrafluoroborate ionic liquids (ILs) with different lengths of alkyl chains. Through measurements of anti-swelling rates, XRD, SEM, 17O NMR, molecular dynamics simulation, zeta potential, flocculation evaluation, interfacial tension and a core flooding experiment based on ultra-low permeability reservoirs, the relationships between the molecular structure and physicochemical properties of ILs have been revealed. Interestingly, one of the selected ILs, imidazole-based tetrafluoroborate ILs (C8-OMImBF4), shows excellent performance, which is helpful to design an effective strategy in promoting fluid transportation in narrow spaces.

Equilibrium solubility measurement of carbon dioxide in hybrid solvents of aqueous N-methyldiethanolamine blended with 1-Methyl-3-octyl-imidazolium tetrafluoroborate ionic liquid at high pressures

Solubility of CO2 in the hybrid solvents composed of aqueous N-methyldiethanolamine (MDEA) blended with 1-methyl-3-octyl-imidazolium tetrafluoroborate ([Omim][BF4]) ionic liquid (IL) was measured at temperatures from (298.15–343.15 K) and pressures of (0.2–4 MPa). The experimental trials were performed in a static high pressure equilibrium cell to determine the CO2 absorption capacity of novel absorbent solutions based on the isochoric saturation technique. The experimental data showed that, by rising the concentration of IL in the absorbent solutions’, the mole fraction of dissolved CO2 gas enhances gradually. Absorption capacity of these aqueous solutions was assessed and compared with pure ILs and alkanolamine solvents, which indicates the solutions studied in this research as better hybrid solvents in terms of CO2 loading. Furthermore, a semi empirical model is used to correlate the solubility data of this work, which presents a good agreement with an absolute average deviation (AAD %) of below 1%.

Cytocompatible drug delivery devices based on poly[(2-dimethylamino) ethyl methacrylate]/chondroitin sulfate polyelectrolyte complexes prepared in ionic liquids

Important researches aim for the development of efficient and cheaper biomedical devices based on natural polysaccharides. In this facet, polyelectrolytes complexes (PECs) are interesting materials for biomedical purposes because they can be prepared without using conventional and volatile organic solvents and toxic crosslinkers, commonly used in the synthesis of chemical hydrogels. For the first time, we used ionic liquids (1-alkyl-3-methylimidazolium tetrafluoroborate ionic liquids, [Bmim][BF4], [Omim][BF4] and [Dmim][BF4]) to prepare poly[(2-dimethylamino) ethyl methacrylate]/chondroitin sulfate (PDMAEMA/CS) PECs in aqueous media. The ionic liquids promoted changes in the PECs morphology, influencing the size of the pore significantly. The presence of ionic liquids in aqueous polyelectrolyte solutions enhanced the interactions between poly[(2-dimethylamino) ethyl methacrylate] (PDMAEMA) and chondroitin sulfate (CS), providing organized structures when compared with the PEC yielded only in an aqueous solution. The materials obtained in the ionic liquids' presence were stable and no toxic against epithelial and fibroblast cells. We can modulate the PEC properties by tuning both ionic liquid type and content.

Cucurbit[8]uril-derived porous carbon as high-performance electrode material for ionic liquid-based supercapacitor

The porosity and electrochemical properties of electrodes play an important role in improving the specific energy of supercapacitors. In this work, a novel macrocycle molecule cucurbit[8]uril (CB8) with cavity diameter of ~ 0.88 nm is synthesized to fabricate the porous carbon electrodes. By monomer synthesis, macromolecule cyclization, octa-cycle purification, and carbonization at 800 °C, the prepared cucurbit[8]uril-carbon (CB8C-800) material has ideal pore size distribution centered at 0.88 nm and high specific surface area of 781.51 m2·g−1. Symmetric supercapacitor device is assembled by using the CB8C-800 electrode and 1-propyl-3-methylimidazole tetrafluoroborate (PMIMBF4) ionic liquid electrolyte with ion diameter of 0.87 nm and wide potential window of 3.8 V. The optimized device achieves a high specific energy of 66.04 Wh·kg−1, along with a satisfactory cycling stability (90.3% capacitance retention after 10,000 consecutive cycle). The results demonstrate an effective porous carbon material derived from cucurbituril for high specific energy supercapacitors.

Electrochemical performance of 1-butyl-4-methylpyridinium tetrafluoroborate ionic liquid electrolyte for graphene-based double layer capacitor

Ionic liquids (ILs) have been emerged as the most promising class of electrolytes to achieve high energy density in electrochemical double layer capacitors (EDLCs) due to their unique properties. In this study, 1-butyl-4-methylpyridinium tetrafluoroborate ([BMPy][BF4]) was explored as the electrolyte for graphene based EDLC in presence of co-solvent. Highly viscous [BMPy][BF4] was diluted with two different organic solvents, namely acetonitrile (AN) and propylene carbonate (PC). Different weight ratios of [BMPy][BF4]: organic solvents were investigated and corresponding variation of EDLC’s performance was observed. Dynamic viscosity of these IL+solvent mixtures was also measured. Three electrochemical techniques, namely cyclic voltammetry, galvanometric charge discharge, electrochemical impedance spectroscopy were employed to analyse the effectiveness of these electrolyte–electrode systems. Maximum operating voltage 2.2 V was achieved for the four out of six studied systems. For PC based electrolytes, no effect of concentration of PC on operating potential window was observed. However with AN, electrochemical stability decreased with increase in solvent weight percentage. The highest specific energy (49 Wh kg−1) and power (4.13 kW kg−1) were obtained for 3:1 weight ratio of IL to AN. Reverse effect on specific capacitance and internal resistance was noticed for AN and PC based electrolytes.

Micropore-Rich Yolk-Shell N-doped Carbon Spheres: An Ideal Electrode Material for High-Energy Capacitive Energy Storage.

Increasing the energy density of electrochemical double layer capacitors (EDLCs) can broaden their applications in energy storage but remains a formidable challenge. Herein, micropore-rich yolk-shell structured N-doped carbon spheres (YSNCSs) were constructed by a one-pot surfactant-free self-assembly method in aqueous solution. The resultant YSNCSs after activation possessed an ultrahigh surface area of 2536 m2 g-1 , among which 80 % was contributed from micropores. When applied in EDLCs, the activated YSNCSs demonstrated an unprecedentedly high capacitance (270 F g-1 at 1 A g-1 ) in 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4 ]) ionic liquid, affording an ultrahigh energy density (133 Wh kg-1 at 943 W kg-1 ). The present contribution provides insight into engineering porous carbons for capacitive energy storage.

Insight into the oxidative desulfurization of high-sulfur petroleum coke under mild conditions: a journey of vanadium-substituted Dawson-type phosphotungstic acid

High-sulfur petroleum coke (HSPC), that is a by-product from slag oil in the coking process of refining, shows versatility values in practical applications and, however, concentrates the majority of organic sulfur. Herein, we design and construct a highly effective CTAB@HPA composites to be explored for the catalytic oxidative desulfurization of HSPC under mild conditions using hydrogen peroxide as the oxidant and 1-butyl-3-methylimidazole tetrafluoroborate ionic liquid as the extractant. The results demonstrate that the sulfur content of HSPC could be strikingly reduced from 4.46 wt% to 2.48 wt% under 60 °C and atmospheric pressure, and that the organic sulfur in HSPC is mainly oxidized to sulfoxide, sulfone and sulfate, which latter can be directly separated from petroleum coke. Moreover, the effect of reaction conditions on the desulfurization performance of HSPC as well as the catalytic oxidation reaction kinetic of HSPC desulfurization was systematically investigated. Furthermore, a mechanism for the oxidative desulfurization of HSPC over CTAB@HPA catalysts was proposed. Therefore, this work provides new insight into how to construct active catalysts for the desulfurization of HSPC under mild conditions.

Ultra-sensitive electrochemical sensor for fenitrothion pesticide residues in fruit samples using IL@CoFe2O4NPs@MWCNTs nanocomposite

In this study, a novel electrochemical sensor was developed for the detection of fenitrothion based on multi-walled carbon nanotubes (MWCNTs), cobalt ferrite nanoparticles (CoFe2O4NPs) and 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim][BF4]) ionic liquid (IL) nanocomposite. The CoFe2O4NPs were synthesized via co-precipitation method and the synthesized nanoparticles S/Nanocomposite was characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermo gravimetric analysis (TGA) and transmission electron microscope (TEM). The obtained results of CV demonstrated that the 7-fold enhancement in the electrochemical signals was achieved with IL@CoFe2O4NPs@MWCNTs@GCE compared to that of a bare GCE. A linear correlation between the peak current and the concentration of FNT (in the range of 0.02–160 µM) was obtained. The estimated limit of detection (3 × SD/Slope) and the limit of quantification (10 × SD/Slope), was found to be 0.0135 µM and 0.0253 µM, respectively. The analytical performance of IL@CoFe2O4NPs@MWCNTs@GCE sensor was successfully evaluated by quantification of FNT in orange as well as in grape fruit extract with satisfactory results.

Enhancing the Photovoltaic Performance and Moisture Stability of Perovskite Solar Cells Via Polyfluoroalkylated Imidazolium Additives.

Although the power conversion efficiency of perovskite solar cells has reached 25.5%, their long-term stability is still a barrier to commercialization. In this work, 1-methyl-3-(3',3',4',4',4'-pentafluorobutyl)imidazolium tetrafluoroborate (MFIM-2) ionic liquid and another two analogues were used as additives to study their interaction mechanism with the FAPbI3 perovskite layer. The results reveal that MFIM-2 suppressed the formation of PbI2 crystals during crystallization, enlarged the grain size, and reduced the defect density, which led to an increased photovoltage of 1.12 V and efficiency of 19.4%. Furthermore, the moisture stability of the solar cell devices was also improved. Devices with MFIM-2 retained above 83% of the original value after 35 days in an atmosphere with about 25% relative humidity, and the perovskite film with MFIM-2 showed no phase transition in a 10 month aging process. These results demonstrate that the additive strategy of the polyfluoroalkylated imidazolium salt is a promising way for simultaneously extending the lifetime and improving the device performance of the perovskite solar cells.

Experimental and DFT calculation study of interaction between silver nanoparticle and 1-butyl-3-methyl imidazolium tetrafluoroborate ionic liquid

The mechanism of stabilization of silver nanoparticles (Ag NPs) by 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid (IL) is elucidated from experimental spectroscopic investigations and density functional theory (DFT) calculations. FTIR spectrum of the synthesized IL stabilized silver nanoparticles reveals small red shift in B–F stretching frequency while C–H stretching remains unshifted. There is no shift in NMR peaks of IL before and after the synthesis of IL stabilized Ag NPs. This suggests that Ag NPs are surrounded by anions of ILs. The optimized structure obtained from density functional theory (DFT) calculations also shows the anionic part of the IL surrounding the Ag nanocluster. This is supported by the IR frequency data calculated using DFT. The calculated binding energy and interaction energy obtained between cluster and IL is considerably attractive. Density of State (DOS) calculation shows that the HOMO-LUMO gap of the Ag cluster-IL composite is significantly lesser than that of the IL alone.

Coarse-grained simulations of ionic liquid materials: from monomeric ionic liquids to ionic liquid crystals and polymeric ionic liquids.

Ionic liquid (IL) materials are promising electrolytes with striking physicochemical properties for energy and environmental applications. Heterogeneous structures and transport quantities of monomeric and polymeric ILs are intrinsically intercorrelated and span multiple spatiotemporal scales, which is more feasible for coarse-grained (CG) simulations than atomistic modelling. Herein we constructed a novel CG model for ethyl-imidazolium tetrafluoroborate ILs with varied cation alkyl chains ranging from C2 to C20, and the interaction parameters were validated against representative static and dynamic properties that were obtained from atomistic reference simulations and experimental characterizations at relevant thermodynamic states. This CG model was extended to study thermotropic phase behaviors of monomeric ILs and to explore ion association structures and ion transport quantities in polymeric ILs with different architectures. A systematic analysis of structural and dynamical quantities identifies an evolution of liquid morphology from homogeneous to nanosegregated structures and then a smectic mesomorphism via a gradual lengthening of cation alkyl chains, and thereafter a distinct structural transition characterized by a monotonic decrease in orientational and translational order parameters in a sequential heating cascade. Backbone and pendant polymeric ILs exhibit evident anion association structures with cation monomers and polymer chains, and striking intra- and interchain coordinations between cation monomers owing to an intrinsic polymer architecture effect. Such a peculiar ion pairing association leads to a progressive increase in anion intrachain hopping probabilities, and a concomitant decrease in anion interchain hopping events with a gradual lengthening of polymeric ILs. The anion diffusivities in polymeric ILs are intrinsically correlated with ion pairing association lifetimes and ion structural relaxation times via a universal power law correlation D ∼ τ-1, irrespective of polymer architectures.

Absolute Trends and Accurate and Precise Gas-Phase Binding Energies of 1-Alkyl-3-Methylimidazolium Tetrafluoroborate Ionic Liquid Clusters from Combined Independent and Competitive TCID Measurements.

Ionic liquid (IL) development efforts have focused on achieving desired properties via tuning of the IL through variation of the cations and anions. However, works geared toward a microscopic understanding of the nature and strength of the intrinsic cation-anion interactions of ILs have been rather limited such that the intrinsic strength of the cation-anion interactions in ILs is largely unknown. In previous work, we employed threshold collision-induced dissociation approaches supported and enhanced by electronic structure calculations to characterize the nature of the cation-anion interactions in and determine the bond dissociation energies (BDEs) of a series of four 2:1 clusters of 1-alkyl-3-methylimidazolium cations and tetrafluoroborate anions, [2Cnmim:BF4]+. The cation was varied over the series: 1-ethyl-3-methylimidazolium, [C2mim]+, 1-butyl-3-methylimidazolium, [C4mim]+, 1-hexyl-3-methylimidazolium, [C6mim]+, and 1-octyl-3-methylimidazolium, [C8mim]+, to determine the structural and energetic effects of the size of the 1-alkyl substituent on the binding. The variation in the strength of binding determined for these [2Cnmim:BF4]+ clusters was found to be similar in magnitude to the average experimental uncertainty in these determinations. To definitively establish an absolute order of binding among these [2Cnmim:BF4]+ clusters, we extend this work here to include competitive binding studies of three mixed 2:1 clusters of 1-alkyl-3-methylimidazolium cations and tetrafluoroborate anions, [Cn-2mim:BF4:Cnmim]+ for n = 4, 6, and 8. Importantly, the results of the present work simultaneously provide the absolute BDEs of these mixed [Cn-2mim:BF4:Cnmim]+ clusters and the absolute relative order of the intrinsic binding interactions as a function of the cation with significantly improved precision. Further, by combining the thermochemical results of the previous and present studies, the BDEs of the [2Cnmim:BF4]+ clusters are more accurately and precisely determined.

1-Butyl-3-Methylimidazolium Tetrafluoroborate Ionic Liquid As an Electrolyte for Electrochemical Reduction of Nitrous Oxide.

Nitrous oxide (N2O), of which global warming potential is 310 times of CO2, is a powerful greenhouse gas [1]. The concentration of N2O has increased steadily from various agricultural and industrial activities such as cultivating crops in low-pH soil and manufacturing semiconductor devices [2,3]. Therefore, the importance of studying N2O reduction is emphasized. Thermal decomposition methods focusing on thermal catalyst have been reported, but there are limits such as process temperature and low efficiency [4,5]. Electrochemical reduction of N2O can be an attractive method since it is conducted at low temperatures and has low energy consumption. However, in aqueous solutions, the electrochemical reduction of N2O inevitably accompanies hydrogen evolution reaction (HER), which is the main side reaction. There were many trials to reduce HER through metal and metal oxide catalysts, but they also had limits in terms of efficiency and high cost of noble metal materials [6-9]. Ionic liquids are promising electrolytes in gas reduction field replacing water because they can avoid hydrogen evolution and enhance the solubility of gaseous reactants. Some imidazolium-based ionic liquids were adopted to electrochemical reduction of CO2 because of their favorable properties such as wide electrochemical potential window and high CO2 dissolution capacity [10,11]. Cations of ionic liquids are known to accept oxygen from CO2, and then return to initial state at counter electrode emitting oxygen [12]. According to the same principle, ionic liquids may also be suitable for the electrochemical reduction of N2O.In this study, an ionic liquid/organic solvent mixture was adopted as an electrolyte for the electrochemical reduction of N2O. The ionic liquid and organic solvent used for electrolyte were 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) and propylene carbonate (PC), respectively. The use of [BMIM][BF4] in place of aqueous solutions could improve the solubility of N2O and also avoid the hydrogen evolution reaction, which is the main side reaction in an aqueous solution.Herein we observed the difference of LSV curves in aqueous solution and [BMIM][BF4]. Hydrogen evolution reaction was excluded, but the low current density was obtained in [BMIM][BF4]. The low electrical conductivity and high viscosity of [BMIM][BF4], the main disadvantages in the context of electrochemical reactions, were compensated on introducing PC. We measured the viscosity and electrical conductivity in various [BMIM][BF4]/PC composition, and the composition of the [BMIM][BF4]/PC was optimized considering both the electrical conductivity and N2O stability in the solution. The current and faradaic efficiency could be evaluated during chronoamperometry in aqueous solution and [BMIM][BF4]/PC. For the optimized [BMIM][BF4]/PC, high current efficiency and faradaic efficiency (>90%) were achieved for N2O reduction to N2.Figure captionsFigure 1. LSV curves for Cu electrode in (a) 0.3 M K2SO4 aqueous solution and (b) [BMIM][BF4]. The scan rate was 50 mV s-1.Figure 2. (a) Viscosity (black line) and conductivity (blue line) changes for [BMIM][BF4]/PC according to [BMIM][BF4] content (b) Current efficiency–time curves recorded at –1.3 V vs. SCE in 0.3 M K2SO4 aqueous solution (blue line) and at –2.27 V vs. Fc/Fc+ in 75 vol% [BMIM][BF4] (red line).

Hierarchical porous N-doped graphene aerogel with good wettability for high-performance ionic liquid-based supercapacitors

The improvement of the wettability between electrode materials and ionic liquid electrolytes is critical to increase the performance of electrode materials for supercapacitors. Herein, we demonstrate the synthesis of a urea phosphate-derived graphene aerogel (UPGA) with good wettability by one-step hydrothermal treatment using graphene oxide (GO) as the precursor and urea phosphate (UP) as both the nitrogen dopant and hydroxyl group protector. The as-obtained UPGA has appropriate doped-N atoms, unique hierarchical porous structure, and good wettability by 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) ionic liquid. The UPGA displays a high specific capacitance of 196.7 F g−1 at 1 A g−1. Moreover, a symmetrical UPGA-based supercapacitor delivers an excellent energy density of 97.2 Wh kg−1 at a power density of 0.9 kW kg−1 and a good cycling stability with the capacitance retention of 78.3% after 5500 cycles at 1 A g−1. Therefore, the UPGA exhibits great potential in supercapacitor as electrode material.

Capillary zone electrophoresis of proteins applying ionic liquids for dynamic coating and as background electrolyte component.

The use of ionic liquids in capillary electrophoresis, either as coating material or as components of the background electrolyte needs systematic standardization to set up optimal conditions. Excellent separation of the proteins was achieved using 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF4]) or 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) ionic liquids using the properly made ionic-liquid-water binary mixtures for the experiments. The binary mixture has a distinctly stable and well perceptible low pH, which depends on the concentration of the ionic liquid, and on the preparation time of the mixture. Optimal conditions for the electrophoretic separation were obtained upon a multivariate analysis of the experimental parameters (applied voltage, migration time, concentration, and type of the ionic liquid). The standardized condition provides a low electroendosmotic flow toward the anode, which, however, did not hinder the proteins to migrate toward the cathode. The migration of cytochrome c, lysozyme, myoglobin, trypsin, and apo-transferrin at a pH around 2, far below the isoelectric points of the proteins, showed RSD values of the migration times less than 7.5% and less than 6.5% when using [emim][BF4] or [bmim][BF4], respectively, either in run-to-run or day-to-day experiments. The determination of the extent of the EOF is not possible with the commonly used EOF markers, due to interaction with the ionic-liquid constituents. The interaction of the ionic liquids with the proteins influences the migration order in zone electrophoresis. This method has been applied successfully for the analyses of real biological samples such as proteins from egg whites and human tears.