Modeling cyclic voltammograms of simultaneous electron and ion transfer reactions at a conic film three-phase electrode

When a neutral electroactive substance is dissolved in a water immiscible organic solvent containing no deliberately added electrolyte, and a droplet of that solution is immobilized on the surface of an electron conductor immersed in an aqueous electrolyte solution, at this three-phase electrode an electrode reaction comprising an electron and ion transfer is observed. Here we report the simulation of cyclic voltammograms assuming a conic geometry of the immobilized droplet. An initial conductivity of the organic phase is established at the liquid ∣ liquid interface by partition of the aqueous electrolyte during a short contact time preceding the voltammetric measurements. Upon anodic polarization of the electrode, the substance in the organic solvent is oxidized while simultaneously anions are transferred from water into the organic phase. The influence of the ohmic overvoltage on the current in single scan and multiple cyclic voltammetry of this reaction is discussed.