An entirely electrochemical preparation of a nano-structured cobalt oxide electrode with superior redox activity

A nano-structured Co oxide electrode (with a Ni substrate) was successfully prepared using an entirely electrochemical process, which included the co-deposition of a Ni-Cu alloy film, selective etching of Cu from the film, and anodic deposition of Co oxide on the obtained nano-porous Ni substrate which had an average pore size of approximately 100nm and a pore density of about 10 ¹³m^-2. The excellent electrochemical activity of the prepared electrode was demonstrated in terms of its pseudocapacitive performance, which was evaluated using cyclic voltammetry (CV) in 1M KOH solution. The specific capacitance of the nano-structured Co oxide measured at a potential scan rate of 10 mVs^-1 was as high as 2200Fg^-1, which is over ten times higher than that of a flat oxide electrode (209 Fg ^-1). The highly porous Co oxide also had superior kinetic performance as compared to a flat electrode. At a high CV scan rate of 50 mVs^-1, the two electrodes retained 94% and 59%, respectively, of their specific capacitances measured at 5mVs^-1.