Consistent diffusion coefficients of ferrocene in some non-aqueous solvents: electrochemical simultaneous determination together with electrode sizes and comparison to pulse-gradient spin-echo NMR results

Janisch, Janina; Ruff, Adrian; Speiser, Bernd; Wolff, Christian; Zigelli, Jonas; Benthin, Steffi; Feldmann, Verena; Mayer, Hermann A.

doi:10.1007/s10008-011-1399-3

Cited by 37 publications

(32 citation statements)

References 45 publications

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“…The diffusionc oefficient of Fc in 0.1 m NBu 4 PF 6 /CH 2 Cl 2 at RT (% 25 8C) [82] was corrected for temperature effects on the solvent viscosity, [83] and the Stokes-Einstein relationship was applied to give 2.0 10 À5 cm 2 s À1 at 17 8C.…”

Section: Diffusion Coefficient Of Fcmentioning

confidence: 99%

(Electro)chemical Oxidation of 6,13‐Bis[tri(isopropyl)silylethynyl]pentacene to its Radical Cation and Dication

et al. 2017

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6,13-Bis[tri(isopropyl)silylethynyl]pentacene is a prototypical molecule for organic semiconductor and photovoltaic materials, which makes its electrochemical (redox) properties highly interesting. However, previous cyclic voltammetric studies have provided only limited information. Kinetic and persistence information and identification of the oxidation product(s) and their further reaction or oxidation have not been reported. Thus, an extended electrochemical and spectroscopic investigation of this compound was conducted in CH Cl and THF electrolytes at Pt electrodes. The electrochemically and chemically generated radical cation of the title compound was characterized by using ESR and UV/Vis/NIR spectroscopy and quantum-chemical modeling. In CH Cl , further oxidation to a dication with chemical reversibility at fast timescales but follow-up reactivity at slow timescales was observed. Pertinent parameters of the electron transfers (formal potentials E , electron transfer rate constants k , electron stoichiometry n) were determined. The diffusion coefficients, D, in the two electrolytes were estimated from electrochemical and pulse gradient spin echo (PGSE) NMR spectroscopy data. Simulations of cyclic voltammograms supported the proposed oxidation mechanism and allowed the estimation of further reaction parameters.

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Section: Diffusion Coefficient Of Fcmentioning

confidence: 99%

(Electro)chemical Oxidation of 6,13‐Bis[tri(isopropyl)silylethynyl]pentacene to its Radical Cation and Dication

et al. 2017

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“…Oxidation of ferrocene to ferrocenium ions is a one-electron reaction and the diffusion coefficient (D) of ferrocene calculated by Janisch et al for a 0.1-1.5 mM ferrocene solution in DMSO is 4.4*10 −6 cm 2 s −1 . 17 Using this D and the limiting current in the 2.58 mM ferrocene solution ( Figure 1A), the radius of the carbon microelectrode was calculated from equation 1 to be 5.54 μm. When the microelectrode potential is stepped from a potential where no reaction occurs to a potential where the reaction is diffusion limited, at small times after polarization, the diffusion limited current at a microelectrode is given by equation 5.…”

Section: Resultsmentioning

confidence: 99%

“…First of all, it is important to consider the impact of the solvent molecules themselves on the basicity of the Li + ion. Solvation energy for the adduct formation between Li + and DMSO can be calculated using the formula in equation 17, developed by Drago et al 28 − H = E A E B + C A C B + R A T B [17] In equation 17, H is the enthalpy (in kcal/mole) of formation of a Lewis acid-base adduct, E A , C A and R A are parameters characteristic of the acid (Li + here), and E B , C B and T B are parameters characteristic of the base. These parameters for Li + are E A = 11.72, C A = 1.45 and R A = 24.21 and these for (CH 3 ) 2 SO are E B = 2.4, C B = 1.47, and T B = 0.65 all values in kcal/mole.…”

Section: Irreversibility Of Oxygen Reduction Reaction In Lithium Saltmentioning

confidence: 99%

Microelectrode Diagnostics of Lithium-Air Batteries

Gunasekara

Mukerjee

Plichta

et al. 2014

J. Electrochem. Soc.

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We demonstrate that a microelectrode can be used as a diagnostic tool to optimize the properties of electrolytes for non-aqueous Li-air batteries, and to elucidate the influence of ion-conducting salts on O 2 reduction reaction mechanisms. Oxygen reduction/evolution reactions on carbon microelectrode have been studied in dimethyl sulfoxide-based electrolytes containing Li + and tetrabutylammonium((C 4 H 9 ) 4 N + ) ions. Analysis of chronoamperometric current-time transients of the oxygen reduction reactions (ORR) in the series of tetrabutylammmonium (TBA) electrolytes, TBAPF 6 , TBAClO 4 , TBACF 3 SO 3 , TBAN(CF 3 SO 2 ) 2 in DMSO revealed that the anion of the salt exerts little influence on oxygen transport. Whereas steady-state ORR currents(sigmoidal-shaped) were observed in TBA-based electrolytes, peak-shaped current-voltage profiles were seen in the electrolytes containing their Li salt counterparts. The latter response results from the combined effects of the electrostatic repulsion of the superoxide intermediate as it is reduced further to peroxide (O 2 2− ) at low potentials, and the formation of passivation films at the electrode. Raman spectroscopic data confirmed the formation of Li 2 O 2 and Li 2 O on the microelectrode surface at different reduction potentials in Li salt solutions. Out of the four lithium electrolytes, namely LiPF 6 , LiClO 4 , LiCF 3 SO 3 , or LiN(CF 3 SO 2 ) 2 in DMSO, the LiCF 3 SO 3 /DMSO solution revealed the most favorable ORR kinetics and the least passivation of the electrode by ORR products.

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“…The diffusion coefficients of Fc 0 , [Fe(CN) 6 ] 3À , and [Ru(NH 3 ) 6 ] 3þ have been established electrochemically in many studies and, importantly, in the case of Fc 0 , its value has been confirmed independently by NMR spectroscopy in some solvents. [10] However, caution should be taken in using [Fe(CN) 6 ] 3À , as heterogeneous kinetics for reduction of these species are notorious for being highly surface-sensitive (see Morris et al [11] and references therein). After A is determined by the use of electrochemical methods, the same methods are usually applied for estimation of D of the test compound, assuming that n, A, and c are now exactly known.…”

Section: Red ð1þmentioning

confidence: 99%

Limitations in Electrochemical Determination of Mass-Transport Parameters: Implications for Quantification of Electrode Kinetics Using Data Optimisation Methods

2017

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Voltammetric quantification of the electrode kinetics for the quasi-reversible reaction requires detailed experiment–theory comparisons. Ideally, predicted data derived from the theoretical model are fitted to the experimental data by adjusting the reversible potential (E0), heterogeneous electron transfer rate constant at E0 (k0), and charge transfer coefficient α, with mass-transport and other parameters exactly known. However, parameters relevant to mass transport that include electrode area (A), diffusion coefficient (D), and concentration (c), are usually subject to some uncertainty. Herein, we examine the consequences of having different combinations of errors present in A, D, and c in the estimation of E0, k0, and α on the basis of the a.c. (alternating current) voltammetric experiment–theory comparisons facilitated by the use of a computer-assisted parameter optimisation algorithm. In most cases, experimentally reasonable errors (<10 %) in the mass-transport parameters do not introduce significant errors in recovered E0, k0, and α values. However, a pernicious situation may emerge when a slight overestimation of A, D or c is included in the model and results in erroneous identification of a reversible redox process as a quasi-reversible one with a report of apparently quantifiable kinetic parameters k0 and α.

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Consistent diffusion coefficients of ferrocene in some non-aqueous solvents: electrochemical simultaneous determination together with electrode sizes and comparison to pulse-gradient spin-echo NMR results

Cited by 37 publications

References 45 publications

(Electro)chemical Oxidation of 6,13‐Bis[tri(isopropyl)silylethynyl]pentacene to its Radical Cation and Dication

(Electro)chemical Oxidation of 6,13‐Bis[tri(isopropyl)silylethynyl]pentacene to its Radical Cation and Dication

Microelectrode Diagnostics of Lithium-Air Batteries

Limitations in Electrochemical Determination of Mass-Transport Parameters: Implications for Quantification of Electrode Kinetics Using Data Optimisation Methods

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