Basic concepts of individual processes

The first knowledge about the relationship between the rate of an electrochemical reaction and the imposed interfacial potential was obtained from the work of Tafel [1] who found empirically that this relationship is exponential if jF is the faradaic current involved, e.g. in the redox reaction 0 + ne=R 

As for the overall mechanism, an essential distinction should be made between two categories. 

A more particular example in this category is electro-crystallization, which can be looked upon as the final elementary step in the reduction 

Naturally, the mathematics of a mechanism will always yield the net rate, v, of the reaction O + n e = R and, by convention, the faradaic current density, jF, is 

It may occur that an electroactive species is present in the system in equilibrium with some electroinactive form. Then, in addition to diffusion, so-called coupled chemical reactions will occur delivering or consuming the electroactive component. If the rate of such a reaction is sufficiently fast, it will appear that all of the species concerned are diffusing simultaneously to take part in the heterogeneous process. If the reaction rate is much lower than that of the diffusion, only the free  

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