The reduction of oxygen on rotating disk glassy carbon electrodes was studied in 0.1M HC1. Reproducible single waves with constant limiting currents over a potential range of 0.5V were obtained after the samples were electrochemically treated: anodic polarization at 2.0V vs. SCE and subsequent cathodic reduction. The number of electrons transferred in the oxygen reduction reaction was calculated to be 2.3. The surface of the glassy carbon was examined by XPS at different stages of the electrochemical treatment. After the anodic treatment, the ratio of oxidized carbon vs. graphitic carbon was higher than 1. The predominant oxygen species were carbonyl groups. Following reduction, the surface had an oxidized vs. graphitic carbon ratio below 0.5 with the oxygen distributed between phenolic and carboxylic groups. The role of
ChemInform Abstract Electrochemically treated glassy carbon electrodes (anodic polarization at 2.0 V and subsequent cathodic reduction) are used for the reduction of oxygen in 0.1 M HCl. It is found that these modified electrodes yield reproducible single waves with constant limiting currents. XPS results show that the ratio of oxidized carbon to graphitic carbon is greater than 1 after the anodic treatment. This ratio decreases to < 0.5 after cathodic reduction. The role of Cl-in the formation of carbonyl groups is discussed.
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