Rotating disk electrode study of electrocatalytic oxidation of ascorbate at Prussian blue modified electrode

Abstract

Electrooxidation of ascorbate has been studied with the use of a rotating disk electrode. The results obtained show an efficient electrocatalytic oxidation of ascorbate at the Prussian blue (PB) modified electrode to proceed in solutions of pH 5.5 and 7.3. Depending on solution pH, the onset potential for ascorbate electrooxidation at PB modified electrode appears shifted by 0.1-0.2 V to lower values, as compared to an unmodified glassy carbon electrode. Within the electrode potential window of 0.3 to 0.5 V vs. Ag/AgCl, and electrode rotation velocity of 50-2000 rpm, the catalytic current obeys Koutecky-Levich equation at a submillimolar ascorbate concentration. Kinetic current densities, obtained from the data treatment, are higher for a pH 5.5 solution, and also at higher electrode potential.

Electrocatalytic reduction of hydrogen peroxide at Prussian blue modified electrode: An in situ Raman spectroelectrochemical study

“…Next to electroreduction of hydrogen peroxide, electrocatalytic oxidation of ascorbic acid (vitamin C) at PB modified electrodes is often considered as a process, potentially important for sensor use [13,32]. Fig.…”

Modeling of electrocatalysis at chemically modified electrodes: a combination of second-order and Michaelis-type chemical kinetics

“…It could be concluded that an increase of the rate of catalytic transformation of reactant according to Eqs. (3,4) leads to increase of an apparent K M . Indeed, an increase of k cat under a constant diffusion coefficient for reactant D means a progressive decrease of a relative diffusion rate as ) and I max (c, d) on α, as obtained for different k cat (as indicated), k = 10 1 l · mol −1 · s −1 (a, c) or 10 2 l · mol −1 · s −1 (b, d) at D n = 10 −9 m 2 · s −1 compared to the rate of chemical transformation of reactant.…”

“…These electrodes contain a thin layer of either organic or inorganic substance which is able to act as an electrocatalyst in electrochemical conversion of solution species. Among many electrocatalytic systems of this kind known, our recent examples relate to electrocatalytic reduction of hydrogen peroxide at Prussian blue-modified electrode [1,2], electrooxidation of ascorbic acid at the same electrode [3], and electrooxidation of some organic species at electrode, modified with redox mediator poly(neutral red) [4], poly(toluidine blue) [5], polyaniline or its derivatives [6][7][8].…”