Electrochemical preparation of cobalt oxide using an autoclave electrolytic cell

Polycrystalline films of cobalt oxides (Co3O4 and CoOOH) with and without Sm were fabricated on platinum substrates by electrochemical oxidation in an autoclave, The cobalt oxides were directly crystallized at temperatures higher than about 100 degrees C during electrolysis. The composition of the cobalt oxides strongly depended on the electrode potential; i.e., Co3O4 and CoOOH were formed in non-noble and relatively noble potential regions, respectively. When Sm was incorporated in the CoOOH by the electrolysis in solutions containing Sm3+, only the c lattice constant was increased due to an expansion in the layer structure.