Electrochemical investigations of kinetics and mechanism of oxidation of caffeic acid in aqueous media using glassy carbon/multi-walls carbon nanotubes modified electrode

Electrochemical investigation of kinetics and mechanism of caffeic acid oxidation was carried out in aqueous phosphate solutions with different pH values. Bare glassy carbon, GC and GC-modified with multi-walls carbon nanotubes, MWCNTs electrodes were used. Markedly improved cyclic voltammetric responses, giving rise to chemically reversible, concerted two-electron oxidation process, were obtained when MWCNTs/GC electrode is used. Importantly, the oxidation behaviour is a function of scan rate, concentration, and pH-dependent. The mechanism is consistent with the transfer of two electrons coupled with two protons. It was concluded that caffeic acid oxidizes chemically following ECEC, radical-radical mechanism. The proposed mechanism was confirmed on comparing the experimental data with the simulated ones.