Transients in convective systems: II . Limiting current and kinetically complicated galvanostatic transients at rotating disc electrodes

Abstract

The shape of the limiting current transient at a rotating disc electrode is considered, limits in time being derived for the applicability of Fick's law and of the steady state, for its description. Interpretation of a galvanostatic transition time, determined when the depolariser takes part in a homogeneous “kinetic” or “catalytic” process, is less convenient in a convective than in a quiescent system if polarisation is affected by passage of a constant current through a solution containing a bulk concentration of the depolariser. When, however, polarisation is achieved by current reversal, the depolariser having been generated by a steady-state condition of the reverse direction of the electrode reaction, the convective system is more advantageous. New functions are presented for the interpretation of steady-state limiting currents in kinetic and catalytic systems.