Electrochemical Behavior of Cobalt Oxide Films Deposited at Conductive Diamond Electrodes

The oxidation of Co(II) at a boron-doped diamond (BDD) electrode was investigated by use of anodic voltammetry. The results shows that this reaction takes place by a mechanism similar to that of cobalt metal oxidation in alkaline media. The voltammetric curves evidence a strong enhancement of the oxygen evolution current in the presence of Co(II). This behavior is consistent with cobalt oxide formation at the diamond electrode surface. Based upon these results, a simple, straightforward method for the production of high activity films on BDD electrode surfaces is demonstrated. The study of the electrochemical behavior in 1 M NaOH shows that the electrodes thus obtained exhibit promising, stable electrocatalytic performance for oxygen evolution, comparing well with those of thermally deposited cobalt electrodes. The use of BDD as a substrate for the electrocatalytic layers allows the deposition of isolated particles or discontinuous films, thus maximizing the utilization of the catalyst by avoiding the need for thick films. © 2003 The Electrochemical Society. All rights reserved.