Study of reversible electrode processes with unsymmetrical cyclic reciprocal derivative chronopotentiometry

In this paper, the theoretical study of cyclic reciprocal derivative chronopotentiometry (CRDCP) for totally reversible electrode processes with symmetrical and unsymmetrical programmed currents is presented. The main viewpoints are: (1) for symmetrical programmed current, the amplitudes of the successive currents are the same, i.e. I(t) = (−1)ⁱ⁺¹I₀, whereas the transition times of each current step, τ_i, have different values. The properties of the dt/dE-E curves corresponding to each current cycle also differ a lot. (2) For unsymmetrical programmed current proposed in this work for the first time, the applied current successively reversed at each transition time steps to different amplitude. The use of this unique programmed current is advantageous versus symmetrical programmed current since the transition times obtained are equal to each other anticipatively, and the dt/dE-E curves also coincide with each other for the successive cycles. In this case, the results obtained in CRDCP are almost similar to those of cyclic voltammetry (CV). The characteristic parameters obtained in the dt/dE-E curves in both cases are quantitatively related to the species concentrations adjacent to the electrode surface and afford simple diagnosis criteria to characterize the reversibility of electrode processes. Properties of reversible electrode processes have also been further studied through the use of more than one current cycle.