Nickel-doped CoO spinel nanospheres embedded in nitrogen-doped carbon composites derived from bimetallic NiCo metal-organic framework as a high-performance asymmetric supercapacitor

In this work, nitrogen-doped porous carbon spheres (NCS) with Ni x Co 3 O 4 composite were derived from a metal-organic framework through a simple hydrothermal method followed by heat treatment. The composition and structure of the resulting Co 3 O 4 /NCS and Ni x -Co 3 O 4 /NCS were regulated by the temperature treatment of nitrogen-doped porous carbon spheres (NCSs) with an organic ligand source. The materials were characterized using a variety of analytical methods such as FE-SEM, XRD, FTIR, XPS, HRTEM, and BET, respectively. The Ni x -Co 3 O 4 /NCS-2 composite has a high surface area of 198 m 2 g −1 and a pore volume of 4.85 cm 3 g −1 . As-prepared Ni x -Co 3 O 4 /NCS-2 electrode delivered a high specific capacitance value of 1284 F g −1 at a current density of 1 A g −1 with excellent cycling stability of 96.9% retention after 3000 cycles. Excellent electrochemical performance is due to the synergetic effect of the porous structure and nitrogen-doped carbon. Moreover, an asymmetric supercapacitor was built using Ni x -Co 3 O 4 /NCS-2 as a positive electrode and MWCNT as a negative electrode, which delivered a maximum power density of 416.7 W kg −1 at an energy density of 26.38 Wh kg −1 with good cycling stability of 92% retention after 3000 cycles. The results demonstrate nitrogen-doped porous carbon spheres (NCS) with Ni x -Co 3 O 4 as a promising electrode material for high-performance supercapacitors. Nitrogen-doped porous carbon spheres (NCS) with Ni x Co 3 O 4 composite were derived from a metal-organic framework through a heat treatment.