Electroaclive species

In addition to IR problems, the restriction placed on diffusion by the thin layer configuration results in the rapid depletion of electroaclive species within the layer, with effectively no concomitant replenishing diffusion from the bulk electrolyte outside of the thin layer. Consider, for example, the reduction of a species 0"+ at an electrode ... 

Construct a cell using a standard hydrogen electrode and an electrode designed around the redox couple of interest. The cel potential E is measured with a high impedance voltmeter under zero current conditions. When using SHE as a reference electrode, E is the desired half-reaction potential [7.13], Should the redox couple have one or more electroaclive species (i) that are solvated with concentration b, E must be measured over a range of b values. 

In chronopotentiometry, a current is applied to the electrode and the potential changes to a value at which the flux of the electroaclive species is sufficient to supply the applied current. After a certain time, the flux of redox species to the surface cannot sustain this current and the potential changes rapidly to a new value at which another species (often solvent or electrolyte) is reduced (or oxidized). This time, termed the transition time t, follows the Sand equation ... 

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See also in sourсe #XX -- [ , , , , , , ]

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