FLOW ASSAY OF IONS AT CHEMICALLY-MODIFIED ELECTRODES - THE POLYPYRROLE/FE(CN)(6)(4-) MODEL SYSTEM

A flow electrochemical cell is described with two working electrodes: a ''generator'' electrode, comprising a glassy carbon disk chemically modified with a polypyrrole/Fe(CN)64- (ppy/FCN) layer, and a ''collector'' glassy carbon electrode further downstream. This system was designed to study the dynamics and quantitative aspects of counterion transport at chemically modified electrodes. In this paper, we explore the quantitative aspects using ppy/FCN as a demonstration model. We show that the efficiency of Fe(CN)64- ejection from the ppy film (on electrochemical reduction of the latter) is sensitive to the film thickness and the reduction potential. New information on the mechanistic aspects of the growth of ppy/FCN films is also presented using chronopotentiometry and electrochemical quartz crystal microgravimetry data.