Radially Dependent Corrective Warburg Problem for a Rotating Disk

1998

The two-dimensional model for the current distribution on a rotating disk below the mass-transfer-limited current developed by Newman is extended here to account for the influence of a finite Schmidt number and to provide the charge distribution in the diffuse part of the double layer. A polynomial expansion in terms of Sc' is developed for the dimensionless concentration derivative at the electrode surface. The charge distribution is estimated under the assumption that specific adsorption can be neglected. This approach requires introduction of only one additional parameter corresponding to the distance between the metal surface and the plane of closest approach f or solvated ions. Zero-frequency asymptotes for the local impedance values, determined from the steady-state calculations, are used to establish the need for a two-dimensional model for the impedance response of a disk electrode.

Section: [181mentioning

confidence: 99%

“…-exPl__11j [24] where r is the charge number of the reacting species. In principle such an expression for the reaction kinetics is valid only in case of deposition reactions.…”

Section: Introductionmentioning

confidence: 99%

Current Distribution on a Rotating Disk Electrode below the Mass‐Transfer‐Limited Current: Correction for Finite Schmidt Number and Determination of Surface Charge Distribution

Durbha

1998

“…Unrealistically large values of the Schmidt number are obtained below the limiting current plateau by either EIS or EHD, and this discrepancy can be as large as 200% or more.24 '25 Preliminary work suggested that this discrepancy may be caused by the nonuniform current, concentration, and overpotential seen at the disk electrode for currents below the limiting current plateau. 26 The EHD method employs a sinusoidal perturbation of the disk rotation rate while the electrode is held at a constant potential at the mass-transfer limited current. The resulting sinusoidal current is measured, and the ratio of the complex current and the amplitude of the disk rotation gives the EHD transfer function.…”

Section: Principles Of Ehdmentioning

confidence: 99%

Application of Measurement Models to Electrohydrodynamic Impedance Spectroscopy

Agarwal

Deslouis

et al. 1996

“…Equation 24 can be written as [26] From boundary condition 17, K 2 ϭ 0. From boundary condition 18, [27] Equation 27 could also be obtained by requiring that the solution be finite as r ϱ.…”

Section: Sc Scmentioning

confidence: 99%

A Mathematical Model for the Radially Dependent Impedance of a Rotating Disk Electrode

Durbha

Tribollet

1999

A mathematical model was developed which accounts for the influence of nonuniform current distribution on the impedance response of a rotating disk electrode. Results obtained using this two-dimensional model were compared against those using the one-dimensional model for impedance developed by Tribollet and Newman. The one-dimensional model was found to be adequate when kinetic limitations cause the current to be uniformly distributed. Significant differences between the one-dimensional and two-dimensional models were seen for fast reaction kinetics where the nonuniform ohmic potential distribution is balanced by a nonuniform concentration overpotential.