Faradaic Reaction Involving Two Adsorbed Species

The only difference obtained is that the value of 0 for one set is replaced by 1 — for the other set of parameters, that is, the surface coverage increases or decreases with the overpotential [213]. However, this parameter is not directly measurable and is calculated from the rate constants, Eq. (5.60). This problem was subsequently discussed in detail in the literature [214—217] and extended to other mechanisms. Other measurements, for example electrogravimetric ones, are necessary to distinguish between the two sets of parameters. In a series of papers, Diard et al. [218-221] studied possible graphs obtained for such a reaction and the general conditions when an inductive loop might be observed [220]. 

The preceding equations were written assuming the Langmuir adsorption isotherm for both species. In the case of the Frumkin adsorption isotherm with negative interaction terms the situation is more complex and multi-steady-state curves can be obtained. Such a situation was discussed by Berthier et al. [222]. 

Electrocatalytic and corrosion reactions often involve two or more adsorbed species. A mechanism involving two adsorbed species and the exchange of two 

Equation (5.89) represents a second-order impedance [223], and its denominator can be expressed in the form [222] 

Depending on the value of the roots of the denominator may be real or complex. Taking into account possible combinations of the values and the nature of the roots and poles, there are at least 54 theoretically different cases [221]. However, not all the cases are experimentally possible. An example of a circuit 

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