Theory of ac-voltammetric current of electron transfer reaction at liquid∣liquid interface

Theoretical equations of ac-voltammetric current or the equivalent admittance and/or impedance of the electron transfer reaction between a redox couple of A species, ARED and AOX, in organic (O) phase and another redox couple of B species, BOX and BRED, in aqueous or water (W) phase at the O∣W interface: ARED(O) + BOX(W) = AOX(O) + BRED(W) are derived when the electron transfer reaction is dc-voltammetric-reversible. The theoretical equations are discussed with reference to the mechanisms by which the electron transfer reaction may take place at the interface, that is, either by the heterogeneous electron transfer reaction mechanism at the interface or by the mechanism in which the homogeneous electron transfer reaction is associated with the ion transfer across the interface.