Clarification of the Mechanism of Interfacial Electron-Transfer Reaction between Ferrocene and Hexacyanoferrate(III) by Digital Simulation of Cyclic Voltammograms

Abstract

The reaction mechanism of electron transfer (ET) between ferrocene (Fc) in nitrobenzene (NB) and Fe(CN)63- in water (W) was clarified by digital simulation of cyclic voltammograms. The voltammograms observed under various concentration conditions could not be elucidated by assuming a heterogeneous ET at the NB/W interface, whereas they were successfully elucidated in terms of the ion-transfer (IT) mechanism, in which a homogeneous ET between Fe(CN)63- and Fc (partially distributed from NB) occurs in the W phase and the interfacial transfer of the resultant ferricenium ion (Fc+) is responsible for the current passage across the interface. The validity of the IT mechanism was further supported by spectroscopic detection of Fc+ produced in the W phase without electrochemical control. These results show that the homogeneous ET proceeds more advantageously than the heterogeneous ET due to a pinpoint collision of redox species at the interface. This may be ascribed to the difference in the volume of reaction fi...