Hydrothermal Synthesis of NiCo2O4/CoMoO4 Nanocomposite as a High-Performance Electrode Material for Hybrid Supercapacitors

Graphical Hollow but not empty :A hollow and porous NiCo 2 O 4 /CoMoO 4 hybrid is prepared through a hydrothermal method. The sample exhibits excellent specific capacitance. An assembled hybrid supercapacitor delivers a high energy density and a long-term cycling performance. Thus, the NiCo 2 O 4 /CoMoO 4 hybrid has a competitive advantage as an electrode material for high-performancesupercapacitors. The hierarchical hollow NiCo 2 O 4 /CoMoO 4 hybrid composite was directly grown on Ni foam (NF) under hydrothermal conditions at 110–140 °C for different growth times. This robust hollow structure benefits from a weakly alkaline environment provided by tetramethyl ammonium hydroxide and can provide a large surface area, low resistance, and many active sites to facilitate electrolyte ion transport and fast redox reactions. The as-prepared NiCo 2 O 4 /CoMoO 4 hybrid with synergetic effects shows improved electrochemical properties with an excellent capacitance (2080 F/g at 1 A/g) and long-term cycling reliability (70 % retention undergoing 3000 cycles at 10 A/g). An assembled hybrid supercapacitor based on the as-prepared NiCo 2 O 4 /CoMoO 4 hybrid electrode delivers a high energy density of 35.63 Wh/kg at a power density of 845 W/kg and a long-term cycling life (capacitance retention of 71.4 % over 9000 cycles). Thus, the as-prepared NiCo 2 O 4 /CoMoO 4 nanocomposite has a definite advantage for supercapacitor electrode materials.