MULTIPLICITY OF ANODIC AND CATHODIC CURRENT PEAKS OBSERVED DURING POTENTIODYNAMIC PERTURBATIONS OF GOLD-SODIUM HYDROXIDE SOLUTION INTERFACES

The Au/NaOH (0.01M ≤ C ≤ 1M) interfaces are investigated under various complex potential perturbation conditions covering both the nonoxide and the oxide potential regions and avoiding the interference of the chemical dissolution of the anodically formed oxygen-containing film. In the former region, two reversible redox electrochemical systems are formed, while in the latter three, apparently more sluggish, electrochemical systems are recorded. The processes occurring in the nonoxide region start just after exceeding the pzc and are probably related to the formation of an Au(OH)ad monolayer. Those in the oxide region yield different undetermined Au(III) species. The cathodic current peak multiplicity of the potentiodynamic E/I profile changes dramatically with both the anodic switching potential and the ratio between the anodic and the cathodic potential sweep rates. These results are associated with the occurrence of aging processes in the anodic film and to changes of the ionic composition produced at the electrochemical interface during cycling. The changes of the E/I displays are in reasonable qualitative agreement with specular reflection data reported in the literature. © 1979, The Electrochemical Society, Inc. All rights reserved.