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. [ABSTRACT FROM AUTHOR]