Hierarchical Cu2O/CuO/Co3O4 core-shell nanowires: synthesis and electrochemical properties.

We prepared hierarchical Cu2O/CuO/Co3O4 core-shell nanowires (NWs) via a facile chemical deposition method followed by calcination for use as the electrode of supercapacitors. The Cu2O/CuO/Co3O4 electrode showed a specific capacitance of 318 F g(-1) at a current density of 0.5 A g(-1). 80% of the original specific capacitance was retained after 3000 cycles at a current density of 5 A g(-1). An asymmetric supercapacitor cell using Cu2O/CuO/Co3O4 NWs as the positive electrode and activated graphene as the negative electrode exhibited a maximum energy density of 12 Wh kg(-1). The electrochemical properties of the electrode were strongly related to the hierarchical nanostructure, which not only provided rich active sites but also shortened ion transport pathways.