The effect of high positive potentials on the different charge transport and charge transfer parameters of poly(o-amnophenol) modified electrodes. A study using cyclic voltammetry, steady-state rotating disc electrode voltammetry and AC impedance mea

摘要

Cyclic Voltammetry was employed to prepare fresh poly(o-aminophenol) (POAP) films and also to degrade them quantitatively. Then, the different behaviour of freshly prepared and degraded POAP films was studied by Steady-State Rotating Disc Electrode Voltammetry and Electrochemical Impedance Spectroscopy when a mediated redox reaction is taking place at the polymer-solution interface. With regard to the last technique, the resulting experimental impedance diagrams of these POAP films, contacting the p-benzoquinone/hydroquinone redox couple, were interpreted on the basis of the homogeneous impedance model described in M.A. Vorotyntsev, C. Deslouis, M.M. Musiani, B. Tribollet, K. Aoki, Electrochimica Actal 44 (1999) 2105-2115. The different dependencies of the charge transfer and charge transport parameters on the degree of degradation of the polymer (theta(Red.Max)), were obtained. The different features of some of these dependencies (for instance, bulk electronic and ionic transport on theta(Red,Max)) were explained in terms of the different mechanisms of electron and proton transport in this polymer Also, similar behaviours of the transversal charge transfer resistance at the metal-polymer interface R-m/f (obtained by impedance spectroscopy) and tire lateral resistance Delta R/R along the electrode (obtained by Surface Resistance measurements), as functions of theta(Red,Max), were explained in terms of two different aspects of the electron motion at metal surfaces contacting a polymeric material. The results of this work allows one to demonstrate that after to subject POAP films to tough conditions, as in some of practical applications of POAP ion and electron diffusion inside the film and rates of interfacial charge transfer processes, are strongly reduced. It should be expected that this deterioration process reduces drastically the efficiency of the material to act in practical applications.