Electrocatalytic Reduction of Dioxygen at the Surface of Glassy Carbon Electrodes Modified by Some Anthraquinone Substituted Podands

The preparation and electrochemical characterization of glassy carbon electrodes modified by some recently synthesized anthraquinone substituted podands were investigated. These compounds were found to be strongly and irreversibly adsorbed on the preanodized glassy carbon electrodes. The electrochemical behavior and stability of the modified electrodes were studied by cyclic voltammetry in acidic aqueous solutions. The influence of pH on the electrochemical behavior of the electrodes was studied and a pH of 4.5 was chosen as the optimum working pH. The ability of the modified electrodes as potential electrocatalysts for the reduction of dioxygen to hydrogen peroxide was tested by cyclic voltammetry, chronomperometry and rotating disk electrode voltammetry. They showed excellent electrocatalytic ability for the reduction of O2at pH 4.5 with overpotentials ranging from 380 to 470 mV lower than the plain glassy carbon electrode. The heterogeneous rate constants for the reduction of O2 at the surface of these modified electrodes were determined by the use of Koutecky-Levich plots. In addition, the apparent diffusion coefficients of O2 in buffered aqueous O2-saturated solution was estimated.