Cyclic voltammetry adsorbed monolayer responses

When the formal potentials of the adsorbed and non-adsorbed redox couples are similar, a single wave is obtained where the contribution of the electron transfer involving the adsorbed species increases with the scan rate. Thus, there is a transition from diffusional-shaped voltammograms at slow scan rates to adsorptive-shaped at fast scan rates. To understand this behaviour and illustrate the characteristics of adsorptive voltammograms let us consider the response in cyclic voltammetry of a monolayer of species A that undergoes a one-electron, fully reversible electron transfer ... 

Schlereth (1999) used the SPR technique coupled with cyclic voltammetry to characterize monolayers of cytochrome-c and cytochrome-c-oxidase adsorbed on gold surfaces modified with different alkanethiol self-assembled monolayers [60]. Different behaviors for enzyme adsorption processes in the modified gold surface were observed. For modified mercapto propioni acid electrodes, the response observed for the cytochrome-c adsorbed may be explained as arising from a potential-dependent adsorption and for cytochrome-c-oxidase appears a conformational change between the two states of the adsorbed oxidase, which gives rise to two species with different electrochemical behaviour. 

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