Cyclic and steady-state voltammetric studies of the mechanism and kinetics of some solute inorganic redox-species reactions at a gold electrode covered with poly-o-phenylenediamine

Application of both cyclic voltammetry and rotating disc electrode technique to the study of the mechanism and kinetics of dissolved redox-species reactions (such as Fe^2+/3+, Fe(CN)^4-/3-₆ and ce^3+/4+) at a Au electrode coated with poly-o-phenylenediamine (PPD) are discussed. The results show that the half-wave potential values for the reduction of these species at polymer modified electrode are distributed near the standard (formal) potential of PPD. In this case the reactions occur at the polymer/solution interface. One extra wave is observed for negatively charged redox-species due to occurrence of the reaction at the metal/polymer interface under semi-infinite diffusion conditions. The difference between the mechanism of electrochemical reactions at electrodes coated with electronically conducting and conventional redox-polymer films is connected with the difference of the equilibrium potential distribution in these two systems.