Rough and Porous Electrodes

It is recognized that porosity or roughness of the electrode surface could be expected to lead to a frequency dispersion of the interfacial impedance even in the absence of detailed considerations of the current distribution problems as outlined above. 

The Laplace transform of this equation is, like the diffusion equation, an ordinary differential equation 

For r and c simple functions of x, the equation becomes a modified Bessel equation and may be solved analytically. For example, in the case of the groove geometry, as considered by de Levie, 

As pointed out by de Levie, however, the most important weakness in the model is the assumption that the current distribution is normal to the macroscopic surface, that is a neglect of the true current distribution. For a rough surface, the lines of electric force do not converge evenly on the surface. The double layer will therefore be charged unevenly, and the admittance will be time and frequency dependence. 

Suppose, if z represents a transmission line z = A(jco) and y is a pure capacitance y = jcaC, then 

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Methods for the Determination of the Real Surface Area of Rough and Porous Electrodes... 

First, we have to consider a flow on a rough and porous electrode of length L (cm) and a cross-sectional area A (cm2) immersed in a torrent of electrolyte with a volumetric flow rate 9 (cm3 s ). The linear flow rate of the electrolyte stream, v (cm s 1), is given by... 

Cylindrical Porous Electrode Model. In electrocatalysis, and in catalysis generally, there is a great interest in increasing the real surface area, especially the electrochemical active area of electrodes. In such cases, porous electrodes are used. First investigations of porous electrodes with EIS were applied by de Levie (for details see Section 2.1.6—Rough and Porous Electrodes), presenting a model describing... 

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