Porous cobalt oxide@layered double hydroxide core-shell architectures on nickel foam as electrode for supercapacitor

The high performance of an electrode relies largely on a scrupulous design of nanoarchitectures and smart hybridization of electroactive materials. A porous core-shell architecture in which one-dimensional cobalt oxide (Co₃O₄) nanowire cores are grown on nickel foam prior to the growth of layered double hydroxide (LDH) shells is fabricated. Hydrothermal precipitation and thermal treatment result in homogeneous forests of 70-nm diameter Co₃O₄ nanowire, which are wrapped in LDH-nanosheet-built porous covers through a liquid phase deposition method. Due to the unique core-shell architecture and the synergetic effects of Co₃O₄ and NiAl-LDH, the obtained Co₃O₄@LDH electrode exhibits a capacitance of 1 133.3 F/g at a current density of 2 A/g and 688.8 F/g at 20 A/g (5.3 F/cm² at 9.4 mA/cm² and 3.2 F/cm² at 94 mA/cm²), which are better than those of the individual Co₃O₄ nanowire. Moreover, the electrode shows excellent cycling performance with a retention rate of 90.4% after 3 000 cycles at a current density of 20 A/g.