Electrochemistry In Ionic Liquids Research Articles

The use of the reference electrode equipped with an ionic liquid salt bridge in electrochemistry of ionic liquids: A convenient way to align the formal potentials of redox reactions in ionic liquids based on the standard hydrogen electrode scale

A hydrophobic ionic liquid composed of a cationic and anionic species having similar magnitudes of hydrophobicity and mobilities can work as a salt bridge separating two electrolyte solutions, that is, the sample solution and the inner solution of the reference electrode. A few examples of superiority of this ionic liquid salt bridge (ILSB) over the traditional salt bridges made of a concentrated aqueous KCl solution have been demonstrated. The present study is a further extension of the use of ILSB to voltammtery of the redox reactions of ferrocene/ferrocenium and cobaltocene/cobaltocenium couples in an ionic liquid, tributyl(2-methoxyethyl) phosphonium bis(pentafluoroethanesulfonyl) amide ([TBMOEP][C2C2N]), which is also used as the ILSB. The obtained mid-point potentials (Ems) are converted straightforwardly to those referred to the standard hydrogen electrode (SHE). A comparison of Em (SHE) values of the two redox couples in [TBMOEP][C2C2N] with the corresponding values in molecular solvents suggests that the environment given by [TBMOEP][C2C2N] to the two redox reactions is macroscopically similar to that of methanol.

A family of chiral ionic liquids from the natural pool: Relationships between structure and functional properties and electrochemical enantiodiscrimination tests

In spite of the increasing fundamental and practical interest of electrochemistry in ionic liquids (ILs), exploration of chiral ionic liquids (CILs) in view of enantioselective electrochemistry and electroanalysis is surprisingly overdue. In this study a family of chiral ionic liquids (CILs) based on natural chiral building blocks, of easy synthesis, is detailedly characterized in terms of thermal and electrochemical properties, achieving valuable information about structure−property relationships on account of the systematicity of available family terms. Moreover, they are submitted to a series of chiral electroanalysis tests. Cyclic voltammetry in bulk CILs or with CIL as additives in a bulk achiral ionic liquid IL, shows small but statistically significant potential differences for the enantiomers of two quite different chiral probes, an interesting result since enantiodiscrimination in terms of potential differences in chiral voltammetry (more desirable respect to current differences) has been only seldom obtained so far. The present first example of enantioselective voltammetry in CIL media with stereocenters as localized chirality sources also offers an important and so far missing confirmation of the intrinsically superior level of the inherent chirality strategy, recently resulting in larger potential differences with the same protocols implemented in "inherently chiral" ionic liquid media. Furthermore, an alternative transduction mode, based on electrochemical impedance spectroscopy EIS, is proposed to effectively highlight the enantiodiscrimination ability of CIL media in analytical experiments.

Decoupling Strategies in Electrochemical Water Splitting and Beyond

Mark Symes was born in London in 1982 and graduated from the University of Cambridge in 2005. After a PhD at the University of Edinburgh with David A. Leigh (FRS), he undertook postdoctoral studies at the Massachusetts Institute of Technology (2009–2010). In late 2010, he returned to the UK and became a postdoctoral researcher at the University of Glasgow. This didn't put them off though, and he joined the faculty at Glasgow in 2013. Since 2016 he has held a Royal Society University Research Fellowship at Glasgow. His research interests span energy conversion, small-molecule activations, electrochemistry, and electrocatalysis. Alex Wallace was born in Swindon in 1993 and graduated with a BSc in Chemistry (first class) from the University of Southampton in 2015. It was in Southampton that he developed a deep interest in electrochemistry, which led him to undertake further study by way of the world's first MSc in Electrochemistry at Southampton, from which he graduated in 2016 with Distinction. Hungry for more electrochemistry, he then immediately joined the Symes group at the University of Glasgow. His research interests include water electrolysis, sonoelectrochemistry, and electrochemistry in ionic liquids.

Evaluation of a Ag/Ag2S reference electrode with long-term stability for electrochemistry in ionic liquids

We report on a reference electrode designed for use in ionic liquids, based on a silver wire coated with silver sulfide. The reference electrode potential is determined by the concentrations of Ag+ and S2−, which are established by the solubility of the Ag2S coating on the Ag wire. While potential shifts of >100 mV during an experiment have been reported when using silver or platinum wire quasi-reference electrodes, the reference electrode reported here provides a stable potential over several months of experimental use. Additionally, our reference electrode can be prepared and used in a normal air atmosphere, and does not need to be assembled and used in a glovebox, or protected from light. The reference electrode has been characterized by voltammetry measurements of ferrocene and cobaltocenium hexafluorophosphate, and was found to slowly drift to more positive potentials at a rate of <1 mV/day for five of the six ionic liquids investigated.

Anomalous electroless deposition of less noble metals on Cu in ionic liquids and its application towards battery electrodes.

Electroless deposition can be triggered by the difference in the redox potentials between two metals in an electrolyte. In aqueous electrochemistry, galvanic displacement takes place according to the electrochemical series wherein a more noble metal can displace a less noble metal. Herein we show anomalous behaviour in ionic liquids wherein less noble metals such as Fe and Sb were deposited on Cu at temperatures from 25 to 60°C. Fe formed spherical structures whereas Cu2Sb/Sb formed nanoplates. A multistep process during the electroless deposition of Sb on Cu took place which was discerned from in situ XPS, and mass spectrometry. In situ AFM was also used to understand the nucleation and growth process of the galvanic displacement reaction. Subsequently, the Cu2Sb/Sb nanoplates were also tested as the anode for both Li-ion and Na-ion batteries. Thus, it is shown that the electrochemistry in ionic liquids significantly differs from aqueous electrolytes and opens up new routes for material synthesis.

Electrochemistry in ionic liquids: Case study of a manganese corrole

Voltammetry of [5,10,15-tris(pentafluorophenylcorrole)]Mn(III) was investigated in four different ionic liquids (ILs): 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIm-TFSI); 1-ethyl-3-methylimidazolium ethylsulfate (EMIm-EtOSO_3); 1-ethyl-3-methylimidazolium triflate (EMIm-OTf); and 1-ethyl-3-methylimidazolium tetracyanoborate (EMIm-TCB). We found that Mn^(IV/III) E_(1/2) values depend on IL counter anion: OTf–< EtOSO_3− < TFSI− < TCB−. In EMIm-TCB and BMIm- TFSI, reversible, diffusion-controlled MnIV/III reactions occurred, as evidenced in each case by the ratio of anodic to cathodic diffusion coefficients over a range of scan rates. Axial coordination was evidenced by a cathodic to anodic diffusion coefficient ratio greater than one, an increasing cathodic to anodic peak current ratio with increasing scan rate, and a split Soret band in the UV-vis spectrum of the complex.

Spatially Resolved Electrochemistry in Ionic Liquids: Surface Structure Effects on Triiodide Reduction at Platinum Electrodes

Understanding the relationship between electrochemical activity and electrode structure is vital for improving the efficiency of dye-sensitized solar cells. Here, the reduction of triiodide to iodide in 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]) room temperature ionic liquid (RTIL) is investigated on polycrystalline platinum using scanning electrochemical cell microscopy (SECCM) and correlated to the crystallographic orientation from electron backscatter diffraction (EBSD). Although the rate determining step in all grains was the first electron transfer, significant grain-dependent variations in activity were revealed, with grains with a dominant (110) crystallographic character exhibiting higher catalytic activity compared to those with a major (100) orientation. The SECCM technique is demonstrated to resolve heterogeneity in activity, highlighting that methods incorporating polycrystalline electrodes miss vital details for understanding and optimizing electrocatalysts. An additional advantage of the SECCM over single-crystal techniques is its ability to probe high index facets.

Vacuum Electrochemistry in Ionic Liquids

Vacuum Electrochemistry in Ionic Liquids

Plasma electrochemistry in ionic liquids: from silver to silicon nanoparticles

In this paper an overview will be given about the generation of metal and semiconductor nanoparticles with plasma electrochemistry using the example of the plasma electrochemistry project in the DFG framework of SPP1191. After an introduction in nanoparticle synthesis and plasma electrochemistry in ionic liquids, we focus on our own results on the synthesis of silver, copper, germanium and silicon nanoparticles. We will present the results in chronological order to exemplify the assumptions, the difficulties and consequences. At the end we will give first indications for the particle forming process during plasma electrochemistry.

ChemInform Abstract: Free Radical Chemistry in Room‐Temperature Ionic Liquids

AbstractReview: 94 refs.

Synthetic Organic Electrochemistry in Ionic Liquids: The Viscosity Question

Ionic liquids are obvious candidates for use in electrochemical applications due to their ionic character. Nevertheless, relatively little has been done to explore their application in electrosynthesis. We have studied the Shono oxidation of arylamines and carbamates using ionic liquids as recyclable solvents and have noted that the viscosity of the medium is a major problem, although with the addition of sufficient co-solvent, good results and excellent recovery and recycling of the ionic liquid can be achieved.

Plasma electrochemistry in ionic liquids: an alternative route to generate nanoparticles

In this perspective, the application of stable glow discharge plasmas as free electrodes for the generation of nanoparticles in ionic liquids is reported. The basic concepts of plasma electrochemistry as well as a few other concepts in this field will be presented. One focus is the interaction of the plasma with the ionic liquids itself and possible influences on the production process of the particles. Several examples of the plasma generation and characterisation of nanoparticles in ionic liquids will be presented. The starting point is thereby the generation of noble metals and at the end the efforts to synthesize semiconductor nanoparticles will be discussed. In all examples the benefits, the difficulties and the challenges of this method and the outcome for the future will be addressed.

The Electrode/Ionic Liquid Interface: Electric Double Layer and Metal Electrodeposition

The last decade has witnessed remarkable advances in interfacial electrochemistry in room-temperature ionic liquids. Although the wide electrochemical window of ionic liquids is of primary concern in this new type of solvent for electrochemistry, the unusual bulk and interfacial properties brought about by the intrinsic strong interactions in the ionic liquid system also substantially influence the structure and processes at electrode/ionic liquid interfaces. Theoretical modeling and experimental characterizations have been indispensable in reaching a microscopic understanding of electrode/ionic liquid interfaces and in elucidating the physics behind new phenomena in ionic liquids. This Minireview describes the status of some aspects of interfacial electrochemistry in ionic liquids. Emphasis is placed on high-resolution and molecular-level characterization by scanning tunneling microscopy and vibrational spectroscopies of interfacial structures, and the initial stage of metal electrodeposition with application in surface nanostructuring.

Semiconductor nanostructures via electrodeposition from ionic liquids

The fascinating properties of ionic liquids make it possible to synthesize semiconductor nanostructures via a simple and low-cost electrochemical pathway. The present paper summarizes our recent work on the synthesis of Si, Ge, and SixGe1–x nanostructures from ionic liquids: thin films, nanowires and photonic crystals. We also introduce our first results on the template-assisted electrodeposition of SixGe1–x photonic crystals from 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIm]Tf2N) ionic liquid, and some optical measurements on the previously prepared Ge photonic crystals. Our results confirm that electrochemistry in ionic liquids is excellently suited to the synthesis of high-quality semiconductor nanostructures.

Ionic liquids in surface electrochemistry

Ionic liquids (IL) are widely used in electrochemistry due to their excellent properties such as good ionic conductivity, wide electrochemical potential window, high viscosity, high thermal stability, wide liquid range and tunable solvent properties. In electrochemistry, the performance of an electrochemical system is dependent on the properties of the interface at the IL/electrode. This review presents the surface electrochemistry in ILs, and the interfacial structures of IL/electrode and heterogeneous electron-transfer kinetics are detailed. Finally, the updated researches on the electrochemical applications of ILs such as electrode deposition, electrosynthesis, electrocatalysis, electrochemical biosensing, electrochemical capacitor and lithium batteries are demonstrated.

Electrochemistry in Room Temperature Ionic Liquids: A Review and Some Possible Applications

A review of electrochemistry in ionic liquids is presented, highlighting some particular examples, with the aim to compare any similarities and differences observed in RTILs to that observed in conventional solvents. The presence of impurities such as halide and water on the electrochemical window and viscosity of RTILs is discussed. Some fundamental electrochemical studies relating to mass transport, heterogeneous electron transfer kinetics and double-layer capacitance are compared to similar studies in conventional solvents, and the suitability of RTILs as solvents in electrochemical experiments is considered. The application of RTILs as replacements for conventional solvents in gas sensors is reviewed, focussing on the electrochemistry observed in RTILs for the following gases: oxygen, a mixture of oxygen and carbon dioxide, and ammonia. The low volatility and high thermal stability of RTILs renders them advantageous for the development of robust sensors under extreme conditions. Finally, the possibility for use of RTILs as solvents in electrosynthesis is discussed, focussing on two examples: the reactivity of electrogenerated bromine with cyclohexene, and the reduction of 4-nitrophenol. It is obvious that RTILs have the ability to offer many advantages over traditional solvents in the field of electrochemistry.

Electrochemistry of Ionic Liquids

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Conducting Polymer Electrochemistry in Ionic Liquids.

Applications of polymers like polypyrrole and polythiophene often require interaction with an electrolyte consisting of solvent and dissolved salt. Ionic Liquids (ILs) are pure salts, fluid at room temperature, that form charged electrolytes. Pure l-Bu-3-Me-Imidazolium PF 6 (BMI PF 6 ). a hydrophobic IL that has a wide potential window, was used to investigate the electrochemistry of polypyrrole. Enhanced electrochemical stability of polypyrrole was obtained on repetitive redox cycling with respect to the equivalent propylene carbonate electrolyte with tetrabutylammonium hexaflurophosphate (TBA PF 6 ) electrolyte.

Electrochemistry in Ionic Liquids

Electrochemistry in Ionic Liquids