Investigation of Electroreduction Kinetics of the Hexaamminecobalt(III) Cations on the Electrochemically Polished Bi Planes by the Electrochemical Impedance Spectroscopy Method

Abstract

Electrochemical impedance spectroscopy has been used for investigation of electroreduction kinetics of hexaamminecobalt(III) cations on the electrochemically polished Bi planes. The total charge transfer resistance obtained depends noticeably on the electrode potential and [Co(NH3)6]3+ concentration. Systematic analysis of results show that the equivalent circuit taking into account the adsorption of one reacting or intermediate particle is the more probable and simplest physical model of the complicated [Co(NH3)6]3+ electroreduction reaction under discussion. The charge transfer resistance, adsorption capacitance and adsorption resistance values depend on the electrode potential as well as on the reactant concentration. In the base electrolyte solution with addition of [Co(NH3)6]3+ the adsorption and charge transfer resistance value was maximal and the adsorption capacitance value was minimal in the region of zero charge potential for Bi single crystal (111) and (011-) planes.