Electrocatalytic oxygen reduction on glassy carbon grafted with anthraquinone by anodic oxidation of a carboxylate substituent

The electrochemical reduction of oxygen on glassy carbon (GC) electrodes modified with anthraquinone was studied using the rotating disk electrode (RDE) technique. Surface modification was performed by anodic oxidation of the carboxylate group of 9,10-anthraquinone-2-ethanoic acid in dimethylformamide (DMF). The modified electrode showed a pronounced electrocatalytic activity towards oxygen reduction in 0.1 M KOH. The kinetic parameters of oxygen reduction were determined using a surface redox catalytic cycle model and the values obtained were compared with those of surface bound anthraquinone grafted by the reduction of its diazonium salt in the absence of a -CH2- tether. The rate constant for the reaction between the semiquinone radical and oxygen showed little dependence on the point of attachment of the quinone. (C) 2005 Elsevier Ltd. All rights reserved.