Catalysis at Monolayer Coated Electrodes

FIGURE 4.12. Koutecky-Levich plot of the variation of the RDEV plateau current with the rotation rate. 

Depending on the catalyst, electron transfer at the electrode is not necessarily fast. The Nemst law used as electrode surface boundary condition may thus have to be replaced by an equation depicting the electron transfer kinetic law (Section 1.4.2)  

Application of these curves may have as other objective to uncover the kinetic characteristics of the electrode electron transfer. This cannot be done in the absence of catalysis since the RDEV response is nil insofar as the steady-state response of an attached species is nil. Cyclic voltammetry could be used instead. The response is not nil, but the signal is in general small, often hardly emerging from the baseline current. Determining the standard potential under these conditions is generally feasible, but an accurate 

Cyclic voltammetry is a useful alternative to RDEV, particularly in the present case, where binding the catalyst to the electrode surface and rotation of the electrode may not be compatible in a number of practical cases. Moreover, scan rates in cyclic voltammetry can be varied over a much wider range than rotation rates in RDEV. 

It should be noted that in most practical circumstances, the Nernstian current can be neglected in front of the catalytic current. 

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