An AC and electrohydrodynamical (EHD) investigation of redox processes occurring at polyaniline coated electrodes.

The redox processes of the [Fe(CN)6]3- 4- couple mediated by polyaniline films were studied by steady-state, ac and EHD impedance methods. At pH < 1, charging and discharging of the polymer capacitance in parallel with the faradaic impedance of the substrate reaction, occurring at the polymer-electrolyte interface, are the processes which determine the transient behaviour. Neither the charge transport across the film nor the charge-transfer kinetics of either the substrate or the polymer are experimentally accessible. At less acidic pHs (~ 3), a low frequency phenomenon detected in EHD experiments seems to be associated with surface protonation equilibria.