Charge-transfer and charge-transport parameters of deactivated poly(o-aminophenol) film electrodes. A study employing electrochemical impedance spectroscopy

Poly(o-aminophenol) (POAP) films were deactivated and then reactivated, and dependences of the different charge-transport and charge-transfer parameters on the degree of deactivation (θc) were obtained by employing electrochemical impedance spectroscopy. These dependences were extracted when the polymer contacts an electroactive solution and a mediation reaction occurs at the polymer|electrolyte interface. While some parameters, such as interfacial metal-film and film-solution resistances (Rm|f, R e f | s , R i f | s ), the high-frequency capacitance (CH) and the redox capacitance (Cp) exhibit a continuous variation without hysteresis between deactivation and reactivation processes within the whole θc range, others, such as electron and ion diffusion coefficients (De, Di), show hysteresis between consecutive deactivation and reactivation processes. On the basis of these findings it was considered that while some parameters of the polymer only depend on the amount of redox active sites, others (De and Di) depend on both the quantity and distribution of redox active sites.