Search

The kinetics of the potentiostatic electroreduction of cadmium oxide layers on polycrystalline cadmium electrodes have been investigated in 0.01–1.0m NaOH solutions. The study was undertaken to determine the influence of passive film formation conditions on the electroreduction process of the anodically produced hydrous cadmium hydroxide-oxide layers. By properly adjusting the electroreduction conditions the cathodic potentiostatic current transients can be satisfactorily described by a nucleation and growth mechanism involving the participation of soluble Cd(II) and passivating anodic species. Experimental data were analysed by the application of non linear least squares fit routines. From the parametric identification procedure coherent potential dependencies of the corresponding fitting parameters as well as reasonable values of the physicochemical constants included in the reaction model, have been obtained. In this way it is possible to correlate kinetic data of the electroreduction process of the anodic oxide layers to make a discrimination between the different mechanistic contributions to this complex reaction involving several steps.