Diffusion current at microdisk electrodes—application to accurate measurement of diffusion coefficients

Kakihana, Masato; Ikeuchi, Haruko; Satô, Gen P.; Tokuda, Koichi

doi:10.1016/s0022-0728(81)80082-4

Cited by 92 publications

(31 citation statements)

References 6 publications

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“…If there are two electrochemical data with different values of x, for example x = 0.5 at a regular electrode and x = 1 for the steady state at a microelectrode [4], the term of D can be eliminated by taking the ratio of the two currents, retaining c. Thus, an absolute value of the concentration can be determined. This concept is close to chronoamperometry of evaluating n or D without knowing the value of either D or n, devised by Kakihana et al [5], who took the ratio of slope and intercept in Cottrell plots (current vs. inverse of the square-root of the electrolysis time) at a microelectrode. This method has been applied to accurate evaluation of D [6][7][8] rather than nc [9].…”

Section: Introductionmentioning

confidence: 99%

Voltammetric Determination of Both Concentration and Diffusion Coefficient by Combinational Use of Regular and Microelectrodes

et al. 2011

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Two Pt disks with 1.6 and 0.1 mm diameter, whose sizes were accurately evaluated, were applied to voltammetric diffusion-controlled currents to determine the concentrations of redox species. Since voltammetric peak currents at a regular electrode, I p , and limiting currents at a microelectrode, I L , are proportional to D 1/2 and D, respectively, the ratio I p 2 /I L is independent of the diffusion coefficient but dependents on the concentration. We used this fact to determine the concentrations of ferrocenyl derivatives, hemin, hexacyanoferrate(II), dioxygen gas and hydrogen gas. New insights are not only the absolute determination of concentrations but also the sensitive detection of adsorption of electrochemical products which blocked the voltammetric currents.

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Section: Introductionmentioning

confidence: 99%

Voltammetric Determination of Both Concentration and Diffusion Coefficient by Combinational Use of Regular and Microelectrodes

et al. 2011

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“…3) was obtained for a 1:37610 À3 m. The diffusion coef®cient value of ferrocyanide used in the calculations is 7.80610 À10 m 2 s À1 which is the average of the values reported by Kakihana et al [17] (7.84610 À10 m 2 s À1 ) and Jung and Kwak [27] (7.75610 À10 m 2 s À1 ).…”

Section: Resultsmentioning

confidence: 63%

Study of the Reduction of 1-(2′-Pyridylazo)-2-Naphthol in Ethanol-Water Solutions

et al. 2000

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“…The D values obtained here for tP?4 s were independent of ti,, and their average (7.78±0.05)X10-10 m2 s-1 agreed with the reference value, (7.84±0.02)X 10-10 m2 s-1, which was determined by means of a chronoamperometric method with PtDE. 5 The NP voltammogram of thallium(I) ions in 0.5 mol dm 3 KNO3 solution showed the reduction step at about -0 .83 V. This reduction step was often accompanied by a small prewave at ca. -0.6 V. The height of the prewave remained less than 10% of the main step, and the limiting current plateau of the main step was well developed over the potential range from -0.9 V to -1.2 V when the electrode had been carefully pretreated as described above.…”

Section: And Discussionmentioning

confidence: 99%

Determination of Diffusion Coefficients by Means of Normal Pulse Voltammetry with a Stationary Disk Electrode

et al. 1991

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Normal pulse voltammetry with a stationary unshielded disk electrode can be used for determining the diffusion coefficients of electroactive species in an electrolyte solution if the pulse interval is sufficiently long to eliminate the effects of the preceding pulse. Two experimental examples are presented: (1) hexacyanoferrate(III) ions in 1 mol dm-3 KCl solution and (2) thallium(I) ions in 0.5 mol dm-3 KNO3 solution. In the former example, the determined diffusion coefficient agreed with the reference value within 1%. In the latter, the agreement was less satisfactory, presumably due to the fact that the reduced form was deposited on the electrode surface. KeywordsDiffusion coefficient, normal pulse voltammetryWe have reported a convenient method for the determination of the diffusion coefficients of electroactive species in electrolyte solutions by means of normal pulse (NP) polarography.1 The present report shows that a stationary unshielded disk electrode (SDE) can be used, instead of a dropping mercury electrode (DME), for the same purpose with a commercial instrument for NP polarography.Some experiments require a solid electrode, since the positive end of the potential window of mercury is rather limited. Among the various types of solid electrodes, SDE, a planar circular electrode lying on the plane of an insulator, is one of the most useful. Mass transfer at SDE is well-defined and much simpler than at DME. The theoretical equation for the diffusion current at SDE is quite accurate and simple enough to be solved for the diffusion coefficient (D), as is shown below.In the following we present an equation for calculating D with sufficient accuracy from the diffusion-limited currents of NP voltammograms, together with the experimental results for two typical cases: 1) the oxidized and reduced forms of the electroactive species were both soluble (the reduction of hexacyanoferrate(III) ions in a potassium chloride aqueous solution at a platinum electrode); 2) the reduced form was deposited on the electrode surface (the reduction of thallium(I) ions in a potassium nitrate aqueous solution at a glassy carbon disk electrode). Theoretical EquationsThe potential application and current sampling patterns of NP voltammetry are the same as those of NP polarography. The electrode is held for a fixed period (tp) at an initial potential (Ei) at which the electrolysis of the object species does not occur; a potential pulse is then applied. The current is sampled at a certain time (t) after pulse application. This sequence is repeated, increasing the pulse height each time. One distinct feature of NP voltammetry is that the electrode surface and the solution in its vicinity are not renewed before each pulse. The electrode surface and the concentration distribution near the electrode, however, is restored, thanks to the effects of reverse electrolysis and diffusion, provided that the electrode potential stays at El for a sufficiently long time.Several workers have derived theoretical equations describing the chronoamperom...

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Diffusion current at microdisk electrodes—application to accurate measurement of diffusion coefficients

Cited by 92 publications

References 6 publications

Voltammetric Determination of Both Concentration and Diffusion Coefficient by Combinational Use of Regular and Microelectrodes

Voltammetric Determination of Both Concentration and Diffusion Coefficient by Combinational Use of Regular and Microelectrodes

Study of the Reduction of 1-(2′-Pyridylazo)-2-Naphthol in Ethanol-Water Solutions

Determination of Diffusion Coefficients by Means of Normal Pulse Voltammetry with a Stationary Disk Electrode

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