Non‐Haloaluminate Room‐Temperature Ionic Liquids in Electrochemistry—A Review

Buzzeo, Marisa C.; Evans, Russell G.; Compton, Richard G.

doi:10.1002/cphc.200301017

Cited by 1,151 publications

(900 citation statements)

References 105 publications

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“…Metallocene derivatives, such as ferrocene (when soluble), are commonly used as effective voltammetric reference standards for ionic liquids. 50,83 For electrochemistry of 6pTTF6 monolayers, the Au(111) working electrode was immersed in a 1 mM 6pTTF6 in BMIOTf solution for approximately 24 h, then rinsed with BMIOTf before being inserted into the electrochemical cell containing fresh BMIOTf electrolyte. In a manner similar to that of the solution-based voltammetry, 1 mM ferrocene was added to the BMIOTf electrolyte at the conclusion of the experiments to calibrate the potential scale to the Fc/Fc + redox couple.…”

Section: ■ Experimental Methodsmentioning

confidence: 99%

Single-Molecule Electrochemical Gating in Ionic Liquids

et al. 2012

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The single-molecular conductance of a redox active molecular bridge has been studied in an electrochemical single-molecule transistor configuration in a room-temperature ionic liquid (RTIL). The redox active pyrrolo-tetrathiafulvalene (pTTF) moiety was attached to gold contacts at both ends through −(CH2)6S– groups, and gating of the redox state was achieved with the electrochemical potential. The water-free, room-temperature, ionic liquid environment enabled both the monocationic and the previously inaccessible dicationic redox states of the pTTF moiety to be studied in the in situ scanning tunneling microscopy (STM) molecular break junction configuration. As the electrode potential is swept to positive potentials through both redox transitions, an ideal switching behavior is observed in which the conductance increases and then decreases as the first redox wave is passed, and then increases and decreases again as the second redox process is passed. This is described as an “off–on–off–on–off” conductance switching behavior. This molecular conductance vs electrochemical potential relation could be modeled well as a sequential two-step charge transfer process with full or partial vibrational relaxation. Using this view, reorganization energies of ∼1.2 eV have been estimated for both the first and second redox transitions for the pTTF bridge in the 1-butyl-3-methylimidazolium trifluoromethanesulfonate (BMIOTf) ionic liquid environment. By contrast, in aqueous environments, a much smaller reorganization energy of ∼0.4 eV has been obtained for the same molecular bridge. These differences are attributed to the large, outer-sphere reorganization energy for charge transfer across the molecular junction in the RTIL.

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Section: ■ Experimental Methodsmentioning

confidence: 99%

Single-Molecule Electrochemical Gating in Ionic Liquids

et al. 2012

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“…ILs are salts usually 25 consisting of poorly interacting anions and cations; due to these weak interactions they display relatively low melting temperatures (<100ºC). [17][18][19][20][21] In addition, ILs typically possess several other physical properties that are desirable in EDLC electrolytes, such as non-flammability, high thermal and chemical stability, and due to their inherent low volatility can be considered to be less hazardous than organic 30 solvent based electrolytes. 17,22 Physical properties other than the ESW of ILs play a crucial role in their performance as electrolytes and vary considerably with the structure of their constituent ions.…”

Section: Introductionmentioning

confidence: 99%

Ionic liquid based EDLCs: influence of carbon porosity on electrochemical performance

2014

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Electrochemical double layer capacitors (EDLCs) are a category of supercapacitors; devices that store charge at the interface between electrodes and an electrolyte. Currently available commercial devices have a limited operating potential that restricts their energy and power densities. Ionic liquids (ILs) are a promising alternative electrolyte as they generally exhibit greater electrochemical stabilities and lower volatility. This work investigates the electrochemical performance of EDLCs using ILs that combine the bis(trifluoromethanesulfonyl)imide anion with sulfonium and ammonium based cations. Different activated carbon materials were employed to also investigate the influence of varying pore size on electrochemical performance. Electrochemical impedance spectroscopy (EIS) and constant current cycling at different rates were used to assess resistance and specific capacitance. In general, greater specific capacitances and lower resistances were found with the sulfonium based ILs studied, and this was attributed to their smaller cation volume. Comparing electrochemical stabilities indicated that significantly higher operating potentials are possible with the ammonium based ILs. The marginally smaller sulfonium cation performed better with the carbon exhibiting the largest pore width, whereas peak performance of the larger sulfonium cation was associated with a narrower pore size. Considerable differences between the performance of the ammonium based ILs were observed and attributed to differences not only in cation size but also due to the inclusion of a methoxyethyl group. The improved performance of the ether bond containing IL was ascribed to electron donation from the oxygen atom influencing the charge density of the cation and facilitating cation–cation interactions.

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“…Due to the high stability of the cations and anions, the electrochemical window can be very wide (ca. 4.5-6 V), 5,6 and consequently some voltammetric peaks, which are normally out of the range of traditional solvents, may be observed. This has been exploited in many electrodeposition studies 7 of some metals and semi-conductors which were not possible to electrodeposit previously.…”

Section: Introductionmentioning

confidence: 99%

“…12 The electrochemical characteristics of RTILs have been more thoroughly discussed in a number of recent review papers. 5,13 Generally, it has been found that electrochemical reactions and mechanisms of organic species in RTILs are the same as in conventional aprotic solvents, 14,15 with any differences mainly due to the higher viscosity of the RTIL lowering the diffusion coefficients of the electroactive species. However, the study of reactions and mechanisms of inorganic species in RTILs is relatively unexplored.…”

Section: Introductionmentioning

confidence: 99%

The electrochemistry of simple inorganic molecules in room temperature ionic liquids

Silvester¹,

Rogers²,

Barrosse-Antle³

et al. 2008

J. Braz. Chem. Soc.

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A eletroquímica de compostos inorgânicos simples em líquidos iônicos a temperatura ambiente (RTIL) é revisada e alguns trabalhos novos nesta área são apresentados. Este artigo focaliza a comparação entre o comportamento eletroquímico em RTILs e em solventes apróticos convencionais. Alguns compostos (iodetos, O 2 , NO 2 , SO 2 , NH 3 ) apresentam reações e mecanismos similares em RTILs e em solventes apróticos (como é observado para compostos orgânicos). Entretanto, outras espécies (nitratos, PCl 3 , POCl 3 ) mostram comportamento excepcionalmente diferente em relação aos solventes tradicionais. Isto torna os RTILs um meio promissor para o estudo de compostos inorgânicos, e destaca a necessidade de maiores investigações nesta área.The electrochemistry of simple inorganic compounds in room temperature ionic liquids (RTILs) is reviewed and some new work in this area is presented. This paper focuses on the comparison between electrochemical behaviour in RTILs and in conventional aprotic solvents. Some compounds (iodides, O 2 , NO 2 , SO 2 , NH 3 ) display similar reactions and mechanisms in RTILs as in aprotic solvents (as is observed for organic compounds). However other species (nitrates, PCl 3 , POCl 3 ) show remarkably different behaviour to traditional solvents. This makes RTILs very promising media for the study of inorganic compounds, and highlights the need for more investigations in this exciting area.

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Non‐Haloaluminate Room‐Temperature Ionic Liquids in Electrochemistry—A Review

Cited by 1,151 publications

References 105 publications

Single-Molecule Electrochemical Gating in Ionic Liquids

Single-Molecule Electrochemical Gating in Ionic Liquids

Ionic liquid based EDLCs: influence of carbon porosity on electrochemical performance

The electrochemistry of simple inorganic molecules in room temperature ionic liquids

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