Electro-oxidation of ascorbic acid catalyzed on cobalt hydroxide-modified glassy carbon electrode

The electrochemical behavior of ascorbic acid on a cobalt hydroxide modified glassy carbon (CHM-GC) electrode in alkaline solution was investi- gated. The process of the involved oxidation and its kinetics were established using the cyclic voltammetry, chronoamperometry techniques, as well as by steady state polarization measurements. The results revealed that cobalt hyd- roxide promotes the rate of oxidation by increasing the peak current; hence as- corbic acid is oxidized at lower potentials, which is thermodynamically more favorable. The cyclic voltammograms and chronoamperometry indicate a cata- lytic EC mechanism is operative with the electrogeneration of Co(IV) as the electrochemical process. Also, the process is diffusion-controlled and the cur- rent-time responses follow Cottrellian behavior. This result was confirmed by steady state measurements. The rate constants of the catalytic oxidation of as- corbic acid and the electron-transfer coefficient are reported.