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

Abstract

Charge transfer processes within Prussian-blue (PB) films were studied by using different non-stationary methods, namely cyclic voltammetry, chronopotentiometry and chronoamperometry, at different film thickness, different type and concentrations of adjacent electrolytes (0.1–1 M KCl with pH 2–4). As 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 that, within the main time interval of the measurements, the current decay satisfies the well-known Cottrell equation. The interpretation of current transients was based on model representations of charge transfer processes in electroactive polymer films. The latter were modeled as a binary electrolyte whose immobile components are the redox centers participating in an electron exchange reaction in the film interior. At the same time, cations absorbed 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 this model. The theoretical conclusions are in good agreement with the obtained experimental data. As a result of the analysis performed, a limiting character of ionic transfer processes in PB films was established.