Choline Chloride-based Ionic Liquid Research Articles

Unravelling High-Load Superlubricity of Ionic Liquid Analogues by In Situ Raman: Incomplete Hydration Induced by Competitive Exchange of External Water with Crystalline Water

A high load-carrying capacity is the key to the practicality of liquid superlubricity, but it is difficult to achieve high load and low friction simultaneously by relying solely on a liquid film. Herein, a choline chloride-based ionic liquid analogue (ILA) macroscale superlubricant is first reported by tuning down strong hydrogen bonding in the ILA via introducing 2-10 wt % water, with a high load of 160 MPa and a low coefficient of friction of 0.006-0.008. In situ Raman reveals that competitive exchange between external water and crystalline water induces weak H-bond-dominated incomplete hydration, conferring a low-shear interface and considerable load-carrying capacity inside the lubricant. It is a hydrodynamic lubrication film rather than a tribochemical/physical adsorption film, allowing it to be applied to friction pairs of various materials. This study unveils the principle of water mediation of high-viscosity ILAs and also provides new insights into the design of practical ILA-based superlubrication materials with high load-carrying capacity.

Enhanced electrochemical determination of quercetin in a choline chloride-based ionic liquid.

Electrochemical techniques have been applied to determine quercetin and to evaluate its antioxidant effect. Deep eutectic solvents as a new generation of green solvents are promising electrolyte catalytically active additives for electrochemical oxidation of quercetin. Herein, in this work, Au was directly electrodeposited on the surface of graphene-modified glassy carbon electrodes, and AuNPs/GR/GC electrodes were fabricated. Choline chloride-based ionic liquids as deep eutectic solvents were readily prepared and applied to detect quercetin in buffer solutions, allowing a detection enhancement. X-ray diffraction and scanning electron microscopy were carried out to characterize the morphology of AuNPs/GR/GCE. Fourier transform infrared spectroscopy was carried out to interpret the H-bond interactions between the DES and quercetin. This electrochemical sensor exhibited good analytical performance. The low detection limit was reduced to 0.5 μM in a 15% DES solution, which was 300% higher than the signal without DES. It proved to be fast and environmentally friendly for the determination of quercetin and the DES had no effect on antioxidant effects of quercetin. In addition, it has been successfully applied in real sample analysis.

Simultaneously Embedding Indomethacin and Electrodeposition of Polypyrrole on Various CoCr Alloys from Ionic Liquids.

The aim of the present investigation is the electrochemical deposition of polypyrrole films from choline chloride-based ionic liquids at various potential, period times and simultaneously an indomethacin embedding and release. The electrodeposition films were performed on CoCr commercial type Wirobond C (WBC) and, Heraenium CE (Hera) using as electroprocedures for deposition cyclic voltammetry and chronoamperometry. The morphology of obtained films was investigated using scanning electron microscopy (SEM). An FT-IR investigation of CoCr alloys before and after electrodeposition was able to identify the presence of polymer and drug. The research included an evaluation of the hydrophilic character of all studied samples and their electrochemical characterization in Tanni Zuchi artificial saliva. In the electrochemical study, the following methods have been used: open circuit potential, electrochemical impedance spectroscopy and potentiodynamic polarization. Indomethacin release from the polymeric film was determined using UV-VIS spectra. Based on Fick’s law of diffusion and indomethacin release profile, a kinetic law for release was established and discussed.

Measurement and Thermodynamic Modeling of Lamotrigine Solubility in the Presence of Some Choline-Based Ionic Liquids

Choline chloride-based ionic liquids (ILs) have recently received a great deal of attention in many fields of science. In this regard, the mole fraction solubility data of lamotrigine (LTG) in the ...

SnO-SnO2 film on carbon steel cycling in a choline chloride-based ionic liquid electrolyte for energy storage devices

Abstract Sn-based film was synthesized cathodically on a high‑carbon steel surface in a non-aqueous deep eutectic solvent-based ionic liquid electrolyte. The electrochemical properties of the resultant coatings in Ethaline ionic liquid were also investigated. The composition and morphology of the Sn-based films, as dependent on the cycling potential in Ethaline, were revealed. The characterization showed that SnO and SnO2 predominated at the reduced and oxidized potentials, respectively. The microstructure of the SnO and SnO2 films was also changed according to cycling potential. The electrochemical performances of the films were measured in Ethaline with regard to supercapacitor applications. The rate limiting reaction between Ethaline and the tin oxide electrode followed a purely diffusional-controlled mechanism. The Sn-based film on steel had a specific capacitance of 23 F g−1 at 5 mV s−1. Specific capacitance retention has a long lifecycle and stability, even after 200 scans. The experimental results demonstrated that the Sn-based oxide coating could be used as an energy storage electrode in a deep eutectic solvent electrolyte.

Comparative Study of Ni-Sn Alloys Electrodeposited from Choline Chloride-Based Ionic Liquids in Direct and Pulsed Current

This work presents, for the first time, the electrodeposition of Ni-Sn alloys in pulse current, from deep eutectic solvents (choline chloride: ethylene glycol eutectic mixture). Additionally, in this study, we report a comparison of the electrodeposition methods known as pulse and direct current. The elemental composition of the films, evaluated from EDX, remained almost constant independently on the electrodeposition parameters. The XRD data revealed the presence of the NiSn metastable phase, which has been confirmed by DSC analysis. This phase shows a nanocrystalline structure with crystallite sizes between 12 and 20 nm. The use of pulse current electrodeposition method has led to an improvement of alloys’ mechanical properties. Moreover, by controlling the electrodeposition parameters, we succeeded in tuning the mechanical properties of the coatings prepared through the PC method. We showed that the hardness parameters exhibited by the Ni-Sn alloys are strongly dependent on their crystallite sizes.

Deposition of Zinc–Cerium Coatings from Deep Eutectic Ionic Liquids

This work studies the electrodeposition of zinc and cerium species on carbon steel substrates from choline chloride-based ionic liquid bath in order to develop a protective coating with anti-corrosion, sacrificial, and self-repairing properties. Hull cell tests were used to study the influence of the current density on composition of the coatings and their morphology. Surface morphology, chemical composition and oxidation state of the obtained coatings were examined by scanning electron microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS), respectively. Furthermore, electrochemical characterization and corrosion tests were performed in order to evaluate the corrosion properties of the electrodeposited Zn–Ce coatings. The cathodic deposition of Zn–Ce was achieved for the first time using the deep eutectic solvent choline chloride-urea as an electrolyte. Cerium was incorporated in the coating as oxide or mixed oxide within the Zn metal matrix. The composition and morphology of the electrodeposited coating were dependent on the applied current density. Electrochemical corrosion tests showed similar corrosion rates for all the coatings. Nevertheless on scratched tests with a ratio area of 15:1, for Zn–Ce coatings cerium oxide somehow migrates from the coating to the high pH cathodic areas developed on the surface of the bare steel substrate. Further study is still necessary to improve the corrosion protection of the Zn–Ce coating for carbon steel.

Electropolishing of nickel and cobalt in deep eutectic solvents

ABSTRACTElectropolishing is a common method for decreasing surface roughness and removing surface irregularities. In this paper the electropolishing of nickel and cobalt are successfully demonstrated in a deep eutectic solvent, comprising a 2:1 molar mixture of ethylene glycol and choline chloride. Voltammetric and electrochemical impedance studies were used to characterise the polishing mechanism and show that film formation occurs prior to polishing. Scanning electron microscopy and atomic force microscopy were used to characterise the morphology before and after polishing and 3D optical microscopy was used in-situ to observe film formation during polishing. This study shows that the impact of film formation and subsequently mass transport are responsible for electropolishing of both metals in the choline chloride-based ionic liquid.

Ni–Mo alloy nanostructures as cathodic materials for hydrogen evolution reaction during seawater electrolysis

In the case of hydrogen production involving seawater electrolysis, one of the main targets is to develop more active cathodic materials, to optimize the efficiency of hydrogen evolution reaction (HER) and, by doing so, enhance the overall energy efficiency of electrolysis. Thus, to develop suitable HER electrocatalysts either an increase of the electrode active surface area or a design of a material having high intrinsic catalytic activity should be taken into consideration, both of them decreasing the HER overpotential. In the present work, various Ni–Mo alloy nanostructures (10–40 wt% Mo) have been prepared involving electrochemical deposition from aqueous and deep eutectic solvent (DES)-based electrolytes as potential cathodic materials suitable for hydrogen evolution reaction during water electrolysis. The electrocatalytic activity of the obtained layers has been investigated using real seawater electrolyte. The determined Tafel slopes suggested that the electrodeposited Ni–Mo alloy coatings follow an HER mechanism controlled by the Volmer reaction step. The EIS results indicated that the use of choline chloride-based ionic liquids as electrolytes facilitated Ni–Mo alloy coatings showing a significant increase in surface roughness. Studies of the intrinsic activity showed that the main contribution towards the apparent activity comes from the increase of the real surface area, although a slight increase of the intrinsic electrocatalytic activity in the case of Ni–Mo alloy coatings electrodeposited on Ni foam was also noticed. These results showed that Ni–Mo alloy coatings electrodeposited from the novel electrolytes based on choline chloride–urea–citric acid ternary mixtures associated with a porous substrate may represent a promising technological approach to build cathodic materials suitable for seawater electrolysis.

Electrodeposition of Co and Co composites with carbon nanotubes using choline chloride-based ionic liquids

The paper presents experimental results regarding the electrodeposition and characterization of cobalt and cobalt composites with carbon nanotubes from a choline-chloride-based deep eutectic solvent.Dispersion stability of multi-walled carbon nanotubes (MWCNTs) was excellent in the eutectic solvent used. According to Raman and XRD analysis, the carbon nanotubes were successfully inserted into the metallic matrix. Furthermore, XRD results suggested that the incorporation of CNTs on the deposit promoted a preferred orientation of the Co crystallites on (220) plane. The Co and Co-composites coatings obtained onto a copper substrate are adherent and uniform. Pure Co deposit was formed by sharp edge grains, Co-composites appeared to be less compact and formed by relatively spherical particles connected by MWCNTS. Furthermore, it was found that the presence of MWCNTs contributed to decreasing the deposit's roughness. From corrosion tests, Co-composite films exhibit a comparable or slightly better corrosion performance as compared to pure Co films.

Ternary Zn–Mn–Sn alloy electrodeposition from an ionic liquid based on choline chloride

Zinc–manganese–tin (Zn–Mn–Sn) ternary alloys have been successfully prepared, for the first time, by electrochemical deposition from a choline chloride-based ionic liquid. The influence of electrolyte composition and electrodeposition potential on the ternary Zn–Mn–Sn alloy surface morphology, composition and corrosion resistance were investigated and contrasted with the characteristics of binary Zn–Mn and Zn–Sn electrodeposits. It was found that the composition of the plating bath and deposition potential have a significant influence on the alloy content, morphology and corrosion properties of the Zn–Mn–Sn alloys. The content of Sn in the ternary alloy increased with a decrease in electrodeposition potential and an increase in concentration of Sn2+ in the electrolyte. The corrosion studies showed that the Zn–Mn–Sn alloys have a synergistic property combining the barrier behaviour afforded by Sn and the strong passive behaviour of Mn, while the sacrificial characteristics are still preserved.

Electrodeposition of Mn and Mn-Sn Alloy Using Choline Chloride-Based Ionic Liquids

The deposition of Mn and Mn-Sn alloy from two deep eutectic solvents (DES) was investigated. Pure Mn deposits were powdery and amorphous regardless the DES used. In contrast, the manganese-tin deposits obtained from the two DES used were adherent. The morphology of the deposits obtained from the different DES was analyzed by SEM, which showed that pure Mn films were fibrous. The morphology of Mn-Sn deposits changed upon changing on the amount of tin in solution or the DES used. The phase composition of the Mn-Sn films were investigated by X-Ray diffraction, which showed that the deposits were formed by different MnxSny intermetallic phases. The metallic content in the deposit changed upon changing the bath composition or the DES used. Using the urea (U) based DES Mn-Sn deposits with a Sn content between 1.8 and 6.7 wt% were obtained. In contrast, using the ethylene glycol (EG) based DES the Sn content in the deposits varied between 33.2 and 59.0 wt%.

Density of aqueous choline chloride-based ionic liquids analogues

Ionic liquids analogues known as Deep Eutectic Solvents (DESs) are increasingly realized in many chemical and industrial applications. The physical and chemical characteristics of these fluids are affected considerably by their moisture content. This study focuses on the evaluation and prediction of the density of choline chloride-based DES aqueous mixtures. The study involved six well known DESs with water mole fraction ranging between 0 and 1 within the temperature range (298.15–353.15K). Since, the density of pure DESs is more than that of water, the resulting aqueous mixtures density trends were similar. The Jouyban-Acree mixture density correlation was adopted for each DES mixture separately with very good prediction accuracy. In addition, an alternative modified model was suggested. This model is capable of predicting all DES mixtures density data based on their corresponding critical properties. Negative excess molar volume suggests formation of stronger H-bond and a more extensive H-bond network within the mixture. This is enhanced by the packing effect created by difference between the molecular structures of the DES and water. The aqueous DES solutions density model presented in this work may assist in evaluating the effect of moisture content on this important physical property. This will further help in adopting proper chemical equipment design considerations and relevant process modeling and simulation calculations.

Electroless and Electrodeposition of Silver from a Choline Chloride-Based Ionic Liquid

The electroless and electrolytic deposition of silver from a solution containing silver nitrate in either an ethylene glycol (EG)-choline chloride based or a urea-choline chloride based ionic liquids has been carried out onto steel and copper cathodes by simple immersion, constant current and constant potential methods at room temperature. It has been found that electroless silver deposits of up to several micronshave been obtained by dip coating from both urea and EG based ionic liquids without the use of catalysts. The influences of various experimental conditions on electrodeposition and morphology of the deposited layers have been investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). It has been observed that crack free bright metallic coloured silver coatings can be obtained from both EG and urea based ionic liquids at the applied deposition potentials up to -0.40 V and applied deposition current densities up to -5.0 A m-2 at room temperature. The cathodic current efficiency for the deposition of Ag is about 99%.

Effect of EDTA and NH4Cl additives on electrodeposition of Zn–Ni films from choline chloride-based ionic liquid

Two additives of ethylene diamine tetraacetic acid (EDTA) and ammonium chloride (NH4Cl) were separately used in the electrodeposition of Zn–Ni alloy films from a deep eutectic solvent. The effects of these two additives on electrodeposition behavior, composition, morphology, and corrosion performance of the Zn–Ni alloys were investigated. The electrodeposition behaviors of Zn–Ni alloy revealed by the cyclic voltammetry show that the addition of EDTA to the Zn–Ni electrolyte enhances the Zn incorporation into the alloy film while the addition of NH4Cl produces an opposite effect by suppressing Zn incorporation into the film. With an increase of EDTA concentration in the electrolyte, the Zn content of the Zn–Ni films increases, while the grain size of the deposits and the current efficiency of the plating process decrease. The increase of NH4Cl concentration in the electrolyte would significantly refine the grain size of the electrodeposited Zn–Ni films, reduce the Zn content and increase the cathodic current efficiency. The corrosion testing indicates that the barrier corrosion resistances of Zn–Ni films electrodeposited from NH4Cl containing electrolytes are superior to those electrodeposited from EDTA-containing electrolytes, which in turn are superior to those electrodeposited from additive-free electrolytes.

Facile electrodeposition of nano-iron films from Fe2O3 in a choline chloride-based ionic liquid

The electrodeposition of nano-iron films from Fe2O3 precursor in an ionic liquid composed of 33·3 mol-% choline chloride (ChCl) and 66·7 mol-% ethylene glycol (EG) has been investigated. The electrodeposition process was carried out at 1·5–1·9 V and 60–120°C for 3 hours. The influences of experimental parameters on the electrodeposition process and the morphology of the deposited nano-iron films were studied. The results show that compact and uniform nano-iron (particle size is approximately 100–200 nm) films can be electrodeposited in the Fe2O3-saturated ChCl-EG ionic liquid at 1·8–1·9 V and 60–120°C. The electrodeposition temperature and applied potential have significant influences on the characteristics of the deposited nano-iron films and the electrodeposition process. It is suggested that the controllable electrodeposition process can be used to prepare nano-iron films with various particle sizes from Fe2O3 in CHCl-EG eutectic melt.

Electroless Displacement Deposition of Nanocrystalline Al on Mg Surface from AlCl3-Emic Room Temperature Ionic Liquid

Introduction Ionic liquids have received considerable attentions recently for their wide use in electrochemistry, synthesis, separation, energy-related applications and so on [1]. As alternative solvents and electrolytes for a number of electrochemical processes, ionic liquids show great advantages comparing with aqueous solution. A range of metal coatings, including water-sensitive metals like Al, Li, Mg, etc, were electrodeposited from ionic liquids [2]. However, the electroless deposition of metals from ionic liquids was rarely reported, except for the deposition of Ag on Cu from a choline chloride-based ionic liquid [3]. Here we report the electroless displacement deposition of Al on Mg from AlCl3-1-ethyl-3-methyl-imidazolium chloride (AlCl3-EMIC) room temperature ionic liquid, especially that nanocrystalline Al can be obtained. Experimental 99.95% Mg substrates used in this study were typically 10×25×1 mm, which were mechanically polished with silicon carbide paper and ultrasonically cleaned with acetone prior to use. An acidic ionic liquid with AlCl3 to EMIC molar ratio of 2:1 was used as the electrolyte. All the experiments referred to AlCl3-EMIC ionic liquid were performed in an argon-filled glove-box at room temperature, in which the oxygen content and moisture were maintained below 1 ppm. To remove the oxide layer on surface, the Mg substrates were firstly electrolytic etched in the 2:1 AlCl3-EMIC ionic liquid at 20 mA/cm2 for 10 min, according to ref. [4-5]. The electroless displacement deposition was carried out by just placing the electrolytic etched Mg plates in the ionic liquid for 20 min or by pulling the etched Mg out of ionic liquid and then placing in the glove-box with the residual ionic liquid on surface for 10 min. The samples after electroless displacement deposition were characterized with X-ray diffraction (XRD) and scanning electron microscope (SEM). Results and discussion XRD pattern of the Mg substrate after deposition is shown in Fig. 1a. The diffraction peaks corresponding to pure Al were clearly detected, which suggests that Al was successfully electroless deposited on Mg surface. The low intensity of Al peaks was due to the low thickness of deposited Al coating. Fig. 1b and Fig. 1c show the SEM micrograph of the deposited Al on Mg. For the sample placed in the ionic liquid (Fig. 1b), the Al crystals can be hardly observed by SEM under the magnification of 50000, while cracks of Al coating can be clearly observed. The deposited Al crystallites should be in the nanometer regime. The cracks of coating might be caused by the high stress in the nanocrystalline Al coating. In the case of placing in the glove-box (Fig. 1c), Al crystals can be clearly observed, which is ca. 200~300 nm. No crack of the coating was observed. Conclusion Al coating was successfully deposited on Mg surface through electroless displacement deposition from AlCl3-EMIC room temperature ionic liquid after an electrolytic etching pretreatment. The results showed that the deposited Al coating was nanocrystalline. Acknowledgment Financial support from National Natural Science Foundation of China (No. 51271166) is gratefully acknowledged.

Comparison of Aqueous and Non-Aqueous Deposition of Cobalt Via Electroplating Method

The purpose of this study is to compare the deposition of cobalt onto a copper substrate from aqueous and non-aqueous cobalt chloride solutions. The aqueous solution had a pH of 2 and had an equal concentration of cobalt as the non-aqueous. The non-aqueous solution consisted of a 2:1 molar ratio ethylene glycol to choline chloride solution. Deposition was performed for 10, 15 and 30 minute intervals with both solutions at 3 volts potential difference between the copper plate and reference. The suitable electroplating temperatures were found to be 70° C for the non-aqueous solution and 22° C for the the aqueous. The aqueous was initially run at 70° C to keep the temperature variable constant, but was found incapable of producing consistent films and was run at a lower temperature of 22° C. The coating deposited by the non-aqueous solution was black of color and had controllable thickness based on time. The aqueous coating was shiny silver, and was measured to be thinner than that of the non-aqueous films, but still had controllable thickness. The black cobalt thin films could have applications in optical systems to reduce parasitic light. Also the non-aqueous has applications in thermal active solar cells as they are conductive and absorb a wide range of the electromagnetic spectrum emitted by the sun, converting it to applicable thermal energy. The metallic looking cobalt thin films could be applied as mirrors in x-ray optics systems after polishing, as they may have different angles of diffraction. Referencies: 1Florea, A.; Anicai, L.; Costovici, S.; Golgovici, F.; Visan, T. 2010, Surf. Interface Anal, 42, 1271-1275 2Abdel-Fattah, T.M.; Crooks, R. SurfaceCharacterization of High Purity Niobium Electropolished with an Ionic Liquid. 2010, ECS Trans, 33, 571 3Abdel-Fattah, T.M.; Loftis, J.D. Surface Characterization of High Purity Metals of Silver and Nickel Electropolished with an Ionic Liquid. 2010, ECS Trans, 25, 57 4Ionic Liquid Electropolishing of Metal Alloys for Biomedical Applications. Abdel-Fattah, T.M.; Loftis, J.D.; Mahapatro, A. 2010, ECS Trans, 25, 57 5Abdel-Fattah, T.M.; Loftis, J.D. Comparison of the Electrochemical Polishing of Copper and Aluminum in Acid and Acid-free Media. 2009, ECS Trans. 25, 327 6Damiano, B.; Wixtrom, A.; Abdel-Fattah, T. Electrochemical Deposition of Cobalt onto the Surface of Copper Using a Choline Chloride-Based Ionic Liquid. 2012, ECS Trans. 50(11) 277-281

Fast synthesis and optical property of SnO nanoparticles from choline chloride-based ionic liquid

A fast, environmentally friendly, and reproducible method is proposed to synthesize SnO nanoparticles in an ionic liquid which consists of choline chloride, urea, and SnCl2·2H2O. The nano-sized SnO particles with a size of about 20–30 nm can be synthesized in 1 min without any further treatment and complicated infrastructures. When prolonging the reaction time, the SnO nanoparticles can be self-assembled into micro-sized balls with the hydrangea geometry. High-resolution transmission electron microscopy shows that the SnO nanoparticle consists of tetragonal structured crystals with the grain size of about 4–6 nm. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy further certify the composition, chemical state, and chemical band of the prepared SnO samples. Moreover, the direct band gap of the SnO samples is highly dependent on the particle architectures. A larger band gap value of about 3.80 eV is obtained in the nano-sized SnO which may be due to the quantum size effect.

Facile fabrication of a robust super-hydrophobic surface on magnesium alloy

A super-hydrophobic surface was successfully fabricated on magnesium alloy by electrodeposition of Zn–Co coating from choline chloride-based ionic liquid and subsequent surface modification. The water contact angle (CA) was measured to be as high as 152̊. Based on surface analysis by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FTIR), the super-hydrophobicity can be attributed to both the rough and porous micro- and nano-scale binary structural Zn–Co coating and surface enrichment of low surface energy stearic acid (SA). The corrosion behavior was investigated with potentiodynamic polarization measurements and it was found that the super-hydrophobic coating considerably improved the corrosion resistant performance of magnesium alloy in 0.1mol/L NaCl solution. In addition, the stability of the super-hydrophobic property was investigated by immersion in aqueous solution, finger touching and abrasion with sandpaper. The results showed that the super-hydrophobic coating exhibited high stability in aqueous solution, the rough surface textures were retained and the coating still exhibited a large contact angle after mechanical destroy.