Study of charge transport processes in Prussian-blue film modified electrodes

Charge transfer processes within Prussian-blue (PB) films were studied by u sing different non-stationary methods, namely cyclic voltammetry, chronopot entiometry and chronoamperometry. at different film thickness, different ty pe and concentrations of adjacent electrolytes (0.1-1 M KCl with pH 2-4). A s a result of the above measurements the electro-diffusion mechanism of the processes was revealed. Using a low amplitude variant of chronoamperometry in the range of electrode potentials from 0.1 to 0.3 V, we established tha t, within the main time interval of the measurements, the current decay sat isfies the well-known Cottrell equation. The interpretation of current tran sients was based on model representations of charge transfer processes in e lectroactive polymer films. The latter were modeled as a binary electrolyte whose immobile components are the redox centers participating in an electr on exchange reaction in the film interior. At the same time, cations absorb ed by the film from the adjacent solution were considered as mobile charge carriers in such films. Theoretical inferences for the current response at low amplitude perturbations in the electrode potential were obtained for th is model. The theoretical conclusions are in good agreement with the obtain ed experimental data. As a result of the analysis performed, a limiting cha racter of ionic transfer processes in PB films was established. (C) 1999 El sevier Science Ltd. All rights reserved.