Films Formed by Oxidation of Ferrocene at Platinum Electrodes

Abstract

Oxidation of ferrocene in acetonitrile resulted in films on Pt electrodes under voltammetric conditions. Films were more readily formed with tetrabutylammonium tetrafluoroborate as the electrolyte than with perchlorate salts. No films were detected when ferrocene was oxidized in aqueous 0.05 M cetyltrimethylammonium bromide (CTAB). Analysis of the films by FT-IR and Auger spectroscopy confirmed iron-containing oxidation products on Pt, presumably from chemical reactions of ferricinium ions. Oxidation of 50-100 mM ferrocene in acetonitrile on Pt yielded insoluble precipitates. Analyses by MS, FT-IR, and UV-visible (water extract), suggested a mixture of oligomeric material and a small fraction of ferricinium ions. Film formation had much less influence on voltammograms on 12.5-micron-radius Pt microdisks than on 0.5-mm-radius Pt. This is consistent with the smaller sensitivity of microelectrodes to chemical reactions following charge transfer. The smaller apparent heterogeneous rate constants (k zero') found for ferrocene on macroelectrodes than on microelectrodes could possibly be influenced by film formation on larger Pt electrodes. Correlations between macro- and microelectrode kinetic data suggest that macroelectrode k zero' values may be valid in a relative sense when ohmic drop is negligible. Bias in k zero's on conventional-sized electrodes should be small in solutions giving minimal film formation, such as micellar CTAB.

Kinetic characterization of the effects of organic solvents on the performance of a peroxidase‐modified electrode in detecting peroxides, thiourea and ethylenethiourea

“…This behavior suggests that the oxidized form of DMFc is not available for re-reduction in acetone. This is in line with similar studies in which ferrocene has been reported to react with acetone, water and alcohols [29].…”

Heterogeneous Electron Transfer Kinetics at the Ionic Liquid/Metal Interface Studied Using Cyclic Voltammetry and Scanning Electrochemical Microscopy

“…41 Moreover, these observations are similar to those observed for solutions of ferrocene in acetonitrile. 42 cm 2 s -1 , which agreed closely with that determined using cyclic voltammetry. The smaller diffusion coefficient in the RTIL compared to a traditional organic solvent has been reported for various other redox species, including ferrocene and is most likely due the high viscosity of the RTIL solvent.…”

Electrochemistry of Encapsulated Guests: Ferrocene inside Cram's Hemicarcerands

“…Ferrocene has frequently been used as a redox-active building block in the preparation of a variety of supramolecular assemblies [29] and is attractive from the electrochemical standpoint because it has a wellcharacterized and reversible anodic electrochemistry. However, Rusling and co-workers [30] have shown recently that the oxidation of ferrocene in acetonitrile (at Pt electrodes) yields insoluble films. Another potential complication related to the use of ferrocene as a guest results from the fact that the reported k 0 values for ferrocene cover a rather wide range and seem to correlate, at least partially, with electrode size.…”