Redox polymers has been highly employed in preparation of modified electrodes and yours electrocatalytic properties studied. This work describes the preparation of modified Pt and Pd electrodes by polymers by cathodic electrodeposition of trans-[RuCl2(vpy)4]. The electrodes were characterized by electrochemical impedance spectroscopy at different dc potentials. The equivalent circuit which simulated electrochemical impedance data obtained for the electrode Pt/poly-trans-[RuCl2(vpy)4] at -186 mV dc was R1(R2Q)C. From Nyquist plots, no significant differences between Pt/poly-trans-[RuCl2(vpy)4] and Pd/poly-trans-[RuCl2(vpy)4] electrodes could be observed. The plots corresponding to different substrates, Pt and Pd, show similar shape, but the RΩ value is higher in Pd electrode. Probably, this can be indication of ohmic fall higher in the Pd/film/solution system. The impedance plots obtained to the polymeric film trans-[RuCl2(vpy)4], deposited on Pt or Pd, vary with the dc potential closely the voltammetric wave of the Ru2+/3+ redox couple. The inclination of the plot corresponding the Warburg diffusion in the Pd electrode is higher than Pt electrode, showing a diffusional control.
modified electrodes; redox polymers; electrochemical impedance spectroscopy
