Electrochemical preparation and characterization of a cobalt oxide-platinum composite with promising capacitive and electrocatalytic features

In the present work, boron-doped diamond polycrystalline films were used as support for direct anodic deposition of the cobalt oxide, and continuous Co3O4 coatings with reasonably good conductivity were obtained by appropriately adjusting the deposition charge. Further electrochemical deposition of platinum particles on the oxide substrate enabled the formation of a stable composite with a specific capacitance of ca. 431 F cm(-3) that compares well with that available with similar materials obtained by non-electrochemical methods. Additional advantages of electrochemically obtained composites are the lower content of noble metal, the uniform distribution of the charge over an extended potential range, and, importantly, the simplicity of the preparation method. It was also found that when deposited on a Co3O4 substrate, Pt particles show, besides an enhanced active surface area, an improved catalytic activity for methanol anodic oxidation. This behavior was tentatively ascribed to the presence of a high amount of platinum-oxidized species.