Surface excess redox components

Elucidation of the mechanism of the catalytic process is a relatively complicated task because of the variety of factors influencing the catalytic reaction. For instance, preconcentration of redox species in the porous films can result in an apparent surface excess, similar to adsorption. Here, semi-integral analysis of voltammetric curves can aid in separating diffusional and surface-confined components (Freund and Brajter-Toth, 1992). 

No longer an independent variable, the electrode potential is determined by the redox concentrations. Accordingly, the surface excess of redox components and charge are also not independently determinable. The expressions for the redox components are shown in the following equation... 

As an example, the surface excess of the quinon-hydroquinone redox components on mercury is shown in Figure 4.7. 

Figure 4.7 Relative surface excess of the redox components quinon and hydroquinone on a mercury electrode. ...

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