Electrode kinetics of the oxidation of hydrogen peroxide at pretreated glassy carbon and carbon fiber electrodes

Abstract

Cyclic voltammograms for the oxidation of H 2O 2 were measured at glassy carbon electrodes which had been carefully polished followed by electrochemical pretreatment. From the dependence of the peak potential and the peak current on the potential sweep rate, the voltammograms were ascribed to a totally irreversible wave with an anodic transfer coefficient of 0.38. The influence of the electrochemical pretreatment on the peak potential was explored in detail. The value of the transfer coefficient was independent of the pretreatment. The intensity of the pretreatment was indicated by the amount of charge consumed by the pretreatment rather than the potential, current density or electrolysis time. Saturation of the pretreatment was observed at 0.3 C/cm 2. The charge-transfer rate constant had a linear relation with the logarithm of this charge. Activation for H 2O 2 was also observed at electrochemically pretreated carbon fiber electrodes which had not been polished. A more effective activation was found when the carbon fiber was heated under vacuum: voltammograms were obtained with good reproducibility and the peak current was proportional to H 2O 2 concentrations higher than 0.1 mmol dm −3.