Electrocatalysis at Polymer-Modified Electrodes The Steady-State Response

Mediated Electrocatalysis at Polymer-Modified Electrodes The Steady-State Response 

FIGURE 2.9. Schematic representation of the transport and kinetics processes within an electrocatalytically active multilayered polymer film according to the Albery-Hillman reaction scheme. The various symbols are explained in the text. 

The substrate enters the polymer film at the polymer/solution interface. The permeability is quantified in terms of a partition coefficient K and a substrate diffusion coefficient Ds. The substrate diffusion coefficient within the film is expected to be less than that exhibited by the substrate when it diffuses in the bulk solution phase. Typically Ds is in the range of 10 -10 cm s as compared to a solution phase diffusion coefficient of ca. 10 cm s  

Charge injection at the electrode/polymer interface bounds the redox species in close proximity to the electrode, and it is normally kinetically facile. This means that the surface concentration of the mediator species By labeled b y is then fixed by the electrode potential via the Nernst equation. The AIB transformation at this inner interface is 

The mathematics is stated in the following way. In the steady-state, the transport and kinetics of mediator and substrate can be quantified in terms of the following expressions  

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