Comparison Between a Charge Transfer Process and an Electrocatalytic Process in Cyclic Voltammetry and Cyclic Voltcoulommetry. Application to the Oxidation of Ferrocyanide at a Ferrocene-Monolayer Modified Gold Electrode

摘要

Ferrocyanide oxidation catalyzed by a ferrocene-alkylthiolate monolayer at gold electrodes has been investigated by using cyclic voltammetry (CV) and cyclic voltcoulommetry (CVC). The voltammetric current-potential curves obtained present a stationary sigmoidal feature which points out to a very high rate constant for the chemical step, whereas the charge-potential curves do not reach an stationary behavior in any case. Simple expressions are presented for the characterization of the CV and CVC curves under Nernstian conditions for the charge transfer step. From these expressions, a value for the chemical rate constant 2.5 x 10(4) M-1 s(-1) has been easily obtained from an anodic plateau of the CV curves or from the linear anodic region of the CVC curves.