Surface characterization of Co3O4 electrodes prepared by the sol-gel method

Co3O4 layers on an Ni support were prepared by the sol-gel method. Their properties were characterized by TGA, XRD and SEM. For comparison, Co3O4 was also prepared by thermal decomposition of Co nitrate. The surface electrochemical response was studied in alkaline solution by cyclic voltammetry at several potential scan rates. The electrochemical analysis included the open circuit potential, the voltammetric peak potentials, and the voltammetric charge. Extrapolation of the charge to scan rates v = 0 and v = infinity allowed the 'electrochemical porosity' to be estimated. The results suggest that Co3O4 from the sol-gel method is less crystalline and more porous, although the highest difference in terms of surface charge with respect to the oxide from the nitrate is only a factor of 2. (C) Elsevier Science S.A.