Electrochemical determination of kinetic parameters of surface confined redox probes in presence of intermolecular interactions by means of Cyclic Voltammetry. Application to TEMPO monolayers in gold and platinum electrodes

Abstract

Application of Cyclic Voltammetry to the characterisation of redox kinetics of surface confined redox probes is usually based on the linear regression of the peak potentials versus the logarithm of the scan rate under fully irreversible redox conditions by following the well-known method due to E. Laviron. This method implicitly assumes the Butler-Volmer formalism under ideal conditions, a fact that, in spite of the broad use of this method, strongly restrict its applicability. Here, we propose a combination of the Marcus-Hush-Chidsey formalism and the presence of intermolecular interactions in order to extract kinetic information of the CV curves. Full-width at half-maximum (fwhm) and its correlation with the peak potentials reveals to be very useful to evaluate both kinetics and interactions influences with high sensitivity and accuracy. Experimental analysis of the CV curves of electroactive monolayers of the persistent radical TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) directly attached to gold and platinum electrodes in two aprotic solvents (Ethanol and Propylene Carbonate) have been carried out.