Effect of Anodic Pretreatment on the Performance of Glassy Carbon Electrode in Acetonitrile and Electrooxidation of Para-substituted Phenols in Acetonitrile on Platinum and Glassy Carbon Electrode

Abstract

In the first part of the work electropolymerisation of phenol was studied at glassy carbon electrode. Rapid fouling of its surface indicated the formation of coherent poly(phenyleneoxide) layer which was demonstrated by the repeated cyclic voltammetric scans. Effect of anodic pretreatment potential in acetonitrile solvent was also investigated and the results showed that at potentials higher than 2 V glassy carbon electrode becomes deactivated. Preanodisation of glassy carbon electrode at 3 V in acetonitrile resulted in diminished anodic peak currents by phenols. It was due to the partial deactivation of electrode surface and its extent increased with the pretreatment time. The electrooxidation of para-substituted phenols (p-Cl-phenol, p-NO2-phenol, p-tertbutylphenol, p-methoxyphenol) in acetonitrile resulted in no fouling layer on platinum electrode and the peak currents were significantly higher than in the first scan of unsubstituted phenol in the same concentration. Glassy carbon deactivated continuously by repeating the scans due to the solvent and bonding of products on the surface.

Coexistence of Substituted Phenols Reduces the Fouling Ability of Phenol in Non-aqueous Solvents

“…Fig. 4 reveals the very visible peak separation (first CVs) where peak at around 1.25 V is related to 4-methoxyphenol and peak at around 1.8 V is attributable to phenol according to earlier studies [6].…”

“…The majority of substituted phenols form dimers as products of their electrooxidation typically the ones having one or more tert-butyl groups [1][2][3][4] and chlorophenols [5]. Previously, we found that some para-substituted phenol give reproducible current signal in acetonitrile on platinum electrode in 50 mM concentration [6]. Notably, this concentration is higher than those generally used by other researchers (mainly in the range of 0-5 mM) showing that the products readily dissolve in acetonitrile and it is also true for many other non-aqueous solvents.…”

Anodic Polymerization of Phenylphenols in Methyl Isobutyl Ketone and Mesityl Oxide: Incorporation of a Cavitand into the Layers Formed for Sensing Phenols in Organic Media

“…Many modifying layers can improve the applicability of electrodes in the analysis of selected compounds; therefore, the different deposits were compared in the analysis of 4-chlorophenol and 4-methoxyphenol. Earlier, we found that the oxidation potential of these phenols differed remarkably [ 23 ]; thus, they could be detected selectively in their coexistence. As 4-methoxyphenol also has a weak susceptibility to fouling in aqueous environments at concentrations that are not too high, its voltammograms were used for displaying the curves so that the layers could be characterized.…”