Electrochemical Rate Constants in Room Temperature Ionic Liquids: The Oxidation of a Series of Ferrocene Derivatives

Fietkau, Nicole; Clegg, Antony D.; Evans, Russell G.; Villagrán, Constanza; Hardacre, Christopher; Compton, Richard G.

doi:10.1002/cphc.200500709

Cited by 80 publications

(103 citation statements)

References 48 publications

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“…Literature reports a diffusion coefficient for ferrocene in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EtMeImNTf 2 ) of 3.35 × 10 −7 cm 2 s −1 [16] and in trimethyln-hexylammonium bis(trifluoromethanesulfone)imide (Me 3 HexNNTf 2 ) of ca. 1 × 10 −7 cm 2 s −1 [15].…”

Section: Discussionmentioning

confidence: 99%

“…So far, the electrochemical behavior of the redox couples cobaltocene/cobaltocenium ion (Cc/Cc + ) and ethylferrocene/ethylferrocenium ion on gold, glassy carbon and platinum disc electrodes in 1-n-butyl-3-methylimidazolium hexafluorophosphate and the electrochemical behavior of several substituted ferrocenes, which adhered to the working electrode surface, have been studied [10]. Electrode kinetics of ferrocene or ferrocene derivatives in ionic liquids has been published [15,16]. The cobaltocene/cobaltocenium couple was studied and suggested as possible reference redox couples in 1-n-butyl-3-methylimidazolium hexafluorophosphate, in 1-ethyl-3-methylimidazolium bis(trifluoromethanesulphonyl)imide as well as in 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulphonyl)imide [11,12].…”

Section: Introductionmentioning

confidence: 99%

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Electrochemical studies of four organometallic redox couples as possible reference redox systems in 1-ethyl-3-methylimidazolium tetrafluoroborate

Waligora

Lewandowski

Gritzner

2009

Electrochimica Acta

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electrochemical studies of four organometallic redox couples as possible reference redox systems in 1-ethyl-3-methylimidazolium tetrafluoroborate

Waligora

Lewandowski

Gritzner

2009

Electrochimica Acta

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“…This diffusion coefficient is comparable in magnitude to that of oxygen in several RTILs [12], but approximately one order of magnitude larger than solid diffusing species in RTILs (cf. 3:35 Â 10 À11 m 2 s À1 for ferrocene in [C 2 mim][NTf 2 ]) [37]. This process was then repeated for the oxidation of H 2 in all RTILs studied, and the experimental and fitted theoretical data is shown in the supplementary information.…”

Section: Potential Step Chronoamperometrymentioning

confidence: 99%

The electrochemical oxidation of hydrogen at activated platinum electrodes in room temperature ionic liquids as solvents

Silvester

Ward

Aldous

et al. 2008

Journal of Electroanalytical Chemistry

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108

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a b s t r a c tThe oxidation of hydrogen was studied at an activated platinum micro-electrode by cyclic voltammetry in the following ionic liquids: [C 2 mim][NTf 2 ], [C 4 mim][NTf 2 ], [N 6,2,2,2 ][NTf 2 ], [P 14,6,6,6 ][NTf 2 ], [C 4 mim][OTf], [C 4 mim][BF 4 ], [C 4 mim][PF 6 ], [C 4 mim][NO 3 ], [C 6 mim]Cl and [C 6 mim][FAP](where ½C n mim þ ¼ 1-alkyl-3-methylimidazolium, ½N 6;2;2;2 þ ¼ n-hexyltriethylammonium, ½P 14;6;6;6 þ ¼ trisðn-hexyltetradecylÞ phosphonium; ½NTf 2 À ¼ bisðtrifluoromethylsulfonylÞamide, ½OTf À ¼ trifluoromethlysulfonate and ½FAP À ¼ trisðperfluoroethylÞtrifluorophosphate). Activation of the Pt electrode was necessary to obtain reliable and reproducible voltammetry. After activation of the electrode, the H 2 oxidation waves were nearly electrochemically and chemically reversible in ½C n mim½NTf 2 ionic liquids, chemically irreversible in [C 6 mim]Cl and [C 4 mim][NO 3 ], and showed intermediate characteristics in OTf À , ½BF 4 À , ½PF 6 À , [FAP] À and other ½NTf 2 À -based ionic liquids. These differences reflect the contrasting interactions of protons with the respective RTIL anions. The oxidation peaks are reported relative to the half-wave potential of the cobaltocenium/cobaltocene redox couple in all ionic liquids studied, giving an indication of the relative proton interactions of each ionic liquid. A preliminary temperature study (ca. 298-333 K) has also been carried out in some of the ionic liquids. Diffusion coefficients and solubilities of hydrogen at 298 K were obtained from potential-step chronoamperometry, and there was no relationship found between the diffusion coefficients and solvent viscosity. RTILs possessing ½NTf 2 À and [FAP] À anions showed the highest micro-electrode peak currents for the oxidation in H 2 saturated solutions, with[C 4 mim][NTf 2 ] being the most sensitive. The large number of available RTIL anion/cation pairs allows scope for the possible electrochemical detection of hydrogen gas for use in gas sensor technology.

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“…Particularly interesting is the role of ILs in ruling the mass transport of electroactive analytes to the electrode/solution interface [5][6][7][8]. Moreover, the nature and characteristics of ILs can influence dramatically the electron transfer kinetics [9,10]. The large differences in size and ionic mobility of the cation and anion can originate selective solvation of solutes with different ionic charge.…”

Section: Introductionmentioning

confidence: 99%

Diffusion regimes at nanoelectrode ensembles in different ionic liquids

Ugo

Moretto

Leo

et al. 2010

Electrochimica Acta

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a b s t r a c tThe electrochemical and diffusion behaviour of different redox probes in different ionic liquids is studied at gold nanoelectrode ensembles (NEEs) in comparison with millimetre sized gold (Au-macro) and glassy carbon (GC) disk electrodes. The redox probes are neutral ferrocene (Fc), the ferrocenylmethyltrimetylammonium cation (FA + ) and the ferrocenylmonocarboxylate anion (FcCOO The CVs of the redox probes at the NEEs are peak shaped at low scan rate (v), while they are sigmoidally shaped at high v, but with some shift between forward and backward patterns. This is indicative of the occurrence of a total overlap (TO) diffusion condition when v is low which becomes a mixed diffusion layers (MDL) regime, with only a partial overlapping of individual diffusion layers, at high v values. In the most viscous IL, namely [P 14,666 ] [N(Tf) 2 ], at v higher than 0.8 V s −1 , a plateau current independent on the scan rate is achieved, indicating the tendency to reach the pure radial regime in this IL. The v values at which the transition between TO and MDL is observed scales directly with D and inversely with the IL viscosity. This behaviour is interpreted on the basis of the dependence of individual diffusion layers at each nanoelectrode on redox probe/IL interaction which fits with existing theoretical models very recently developed for nanoelectrode arrays.

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Electrochemical Rate Constants in Room Temperature Ionic Liquids: The Oxidation of a Series of Ferrocene Derivatives

Cited by 80 publications

References 48 publications

Electrochemical studies of four organometallic redox couples as possible reference redox systems in 1-ethyl-3-methylimidazolium tetrafluoroborate

Electrochemical studies of four organometallic redox couples as possible reference redox systems in 1-ethyl-3-methylimidazolium tetrafluoroborate

The electrochemical oxidation of hydrogen at activated platinum electrodes in room temperature ionic liquids as solvents

Diffusion regimes at nanoelectrode ensembles in different ionic liquids

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