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

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.