Levich equation rotating disc electrode

To find that the limiting current at a rotated disc electrode (RDE) is directly proportional to the concentration of analyte, according to the Levich equation. 

Provided that the flow is laminar, and the counter electrode is larger than the working electrode, convective systems yield very reproducible currents. The limiting current at a rotated disc electrode (RDE) is directly proportional to the concentration of analyte, according to the Levich equation (equation (7.1)), where the latter also describes the proportionality between the limiting current and the square root of the angular frequency at which the RDE rotates. 

The development of convective-diffusion theories is due principally to Prandtl9 and Schlichting10, and their application in electrochemistry to Levich11. Levich was the first to solve the equations for the rotating disc electrode. 

Miller and Bruckenstein [27,28] introduced the hydrodynamically modulated rotating disc electrode (HMRDE) in 1974. The steady-state current density at a rotating disc electrode is well-defined, given by the Levich equation (equation (10.15)) ... 

The elimination of transport effects is not so readily achieved. One relatively simple procedure is to measure currents (/m) as a function of electrode angular velocity (co) using a rotating disc electrode. Currents free of diffusive transport effects (/k) can then be obtained by application of the Koutecky-Levich equation,... 

The limiting current, iL, of the rotating disc electrode is given by the Levich equation [1]... 

The contribution of diffusion overpotential to the total overpotential can be achieved by an increase of convection near the electrode surface. In a very controlled manner this is possible with the rotating disc electrode. In the Koutecky—Levich equation the separation of diffusion contributions and charge transfer contributions to the overpotential was achieved. A general charge transfer reaction with exchange of n electrons was chosen. The Koutecky-Levich equation is... 

Fig. 5. Current voltage curves for the reduction of N2O on a silver rotating disc electrode. The limiting currents obey the Levich equation.

The Levich equation for the transport-limited current, Fiim, at a rotating disc electrode is given by... 

Up until the mid-1940s, most physical electrochemistry was based around the dropping mercury electrode. However, in 1942, Levich showed that rotating a disc-shaped electrode in a liquid renders it uniformly accessible to diffusion, yet the hydrodynamics of the liquid flow are soluble and the kinetic equations relatively simple. In addition, in contrast to the case of a stationary planar electrode, the current at an RDE rapidly attains a steady-state value. 

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