PREPARATION AND MODIFICATION OF HYDROUS THICK COBALT OXIDE LAYERS - VOLTAMMETRIC CHARACTERISTICS OF ROUGH CO3O4-SPINEL-TYPE ELECTRODES

The application of a periodic perturbing potential to a cobalt electrode immersed in alkaline solutions at room temperature allows accumulation of a hydrous cobalt hydroxide overlayer which becomes a precursor to the production of a rough Co3 O4 spinel film through subsequent thermal treatment at 480-degrees-C. The optimal working conditions for the application of this procedure are discussed. The properties of the resulting overlayers were determined through voltammetry, X-ray analysis, infrared spectroscopy, thermal gravimetric and differential thermal analysis, and SEM micrography. The explanation of the entire process is given in terms of sequential electrochemical oxidation and reduction reactions involving different Co-containing species. The electroreduction reactions including the HER, play an important role in determining the characteristics of the resulting Co3 O4 overlayer.