Kinetic study of electrocatalytic oxidation of carbohydrates on cobalt hydroxide modified glassy carbon electrode

Abstract

This study investigated the electrocatalytic oxidation of fructose, sucrose, glucose, lactose, arabinose and maltose on nanoparticles of cobalt hydroxide electrodeposited on the surface of glassy carbon electrode in alkaline solutions. Cyclic voltammetry (CV), chronoamperometry (CA) techniques and also steady state polarization measurements have been employed. In CV studies, in the presence of carbohydrate the increase of the peak current of the oxidation of cobalt hydroxide is followed by a decrease in the corresponding cathodic current. This indicates that carbohydrates were oxidized by the redox mediator which was immobilized on the electrode surface via an electrocatalytic mechanism. With the use of Laviron's equation, the values of anodic and cathodic electron-transfer coefficients and charge transfer rate constant for the immobilized redox species were determinated as 0.71 ± 0.03, 0.33 ± 0.03 and 0.21 ± 0.02 s-1, respectively. The rate constant, the electron transfer coefficient and the diffusion coefficients involved in the electrocatalytic oxidation of carbohydrates were determined.