Electrochemical impedance spectroscopy and cyclic voltammetry of ferrocene in acetonitrile/acetone system

Abstract

The oxidation of ferrocene (FeCp 2 ) to ferrocenium cation (FeCp 2 ? ) (where Cp: cyclopentadienyl anion, C 5 H 5 -) was investigated by means of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) on either platinum (Pt) or glassy carbon (G-C) electrodes in acetonitrile (ACN), acetone (ACE), and acetonitrile (ACN)/ acetone (ACE) binary mixtures with n-tetrabutylammonium hexafluorophosphate (TBAPF 6 ) as background electrolyte at T = 294.15 K. The half-wave potentials (E 1/2 ), the diffusion coefficients (D), and the heterogeneous electrontransfer rate constants (k s ) were derived. The activation free energies for electron transfer (DG exp = ) were experimentally determined and compared with the theoretical values (DG cal = ). The electron-transfer process was reversible and diffusion-controlled in all investigated solvent mixtures. The changes on the metal-ligand bond lengths upon electron transfer were almost insignificant. The E 1/2 values were shifted to less positive potentials with the increase of the ACN content. The k s values obtained on Pt electrode were slightly larger compared to k s measured on G-C electrode, while in both cases the k s values were diminished with the enrichment of the mixtures in ACN. The EIS spectra confirmed that the rate-determining step in the whole process is the diffusion of the FeCp 2 species and thus the process can be properly characterized as diffusion-controlled.

The measurement of the diffusion coefficients of ferrocene and ferrocenium and their temperature dependence in acetonitrile using double potential step microdisk electrode chronoamperometry

“…To this end, the redox behaviour of the model FcjFc + system has been subject of many electrochemical reports. The electrochemical oxidation of ferrocene to the monocation ferrocenium, has been investigated in numerous solvents, including ethanol, propylenecarbonate, dimethylformamide [6,7], methanol [8], nitrobenzene, tetrahydrofuran, pyridine, benzonitrile [5], chloroform [9], dimethylsulfoxide [6], acetone [10] and commonly, acetonitrile [4,6,[10][11][12][13][14]. The majority of these studies have been undertaken at room temperature, with the exception of that by Crooks et al who studied the system at temperatures between 298 and 573 K [13].…”

Leveraging e-Science infrastructure for electrochemical research

“…0.25 cm s −1 . The bound k 0 > 0.25 cm s −1 is much larger than the ones proposed in the literature by Tsierkezos & Ritter [18] and Xiao et al [19] and were measured by the DC cyclic voltammetry method. This indicates that a higher detection limit is accessible in the large-amplitude FT AC voltammetric technique.…”

Hybrid amperometric and potentiometrie sensing based on a CMOS ISFET array

“…3(b). The peaks around 400 mV are characteristic of ferrocene's half-wave potential [8]. Even though the chosen scan rate has a high value the response demonstrates a typical CV, due to the use of microelectrodes.…”