Construction of CuCo2O4@CuCo2O4 hierarchical nanowire arrays grown on Ni foam for high-performance supercapacitors

Abstract

In this study, hierarchical CuCo₂O₄@CuCo₂O₄ nanowire arrays have been directly fabricated on Ni foam via a two-step method that involves hydrothermal and calcination processes. The CuCo₂O₄ nanowires are fully covered by porous CuCo₂O₄ nanosheets. The as-prepared double-metal oxide hierarchical nanowire arrays exhibit superior redox reactivity for supercapacitors. The unique hierarchical nanowire arrays own a specific capacitance of up to 888.9 F g⁻¹ at 2 mA cm⁻², which is much higher than the specific capacitance values of simple CuCo₂O₄ nanowire arrays. The hierarchical CuCo₂O₄ nanostructure shows superior cycling stability, retaining 101.77% of the initial capacitance after 2000 cycles. Moreover, by employing CuCo₂O₄@CuCo₂O₄ as the positive electrode and active carbon (AC) as the negative electrode, an asymmetric supercapacitor (ASC) device was fabricated and it displayed an excellent electrochemical performance. The enhanced electrochemical performance is mainly due to its unique hierarchical structure, which provides good ion and electron transfer, a large number of active sites, and the synergistic effect. In view of their outstanding electrochemical performance and the cost-effective fabrication process, this unique integrated nanoarchitecture may offer great promise as superior electrodes for high-performance supercapacitors.