Nitrogen-Doped 3D Graphene/MWNTs Nanoframework-Embedded Co₃O₄ for High Electrochemical Performance Supercapacitors

Co 3 O 4 nanoparticles embedded on three-dimensional (3D) nitrogen-doped graphene incorporated with multiwalled carbon nanotubes (named as 3D N-G/MWNTs) are synthesized through a simple hydrothermal process and succedent microwave treatment. Small-sized Co 3 O 4 in situ grow on the surface of N-doped multiwalled carbon nanotubes and N-doped graphene nanosheets via a rapid one-pot microwave-assisted method without adding other reagents. Owing to the good electrical conductivity unique structure of 3D N-G/MWNTs, the composite electrodes suggested a huge surface active area and an abundant three-dimensional porous configuration to provide plenty of paths for the rapid electrons/ions transportation and electron-transfer resistances. When the l A/g current density is applied, capacitances of 2039.4 F/g are fulfilled. Even with the charge–discharge current increasing from 1 to 15 A/g, there is still 84% of the capacitance remaining. In particular, the hybrid also exhibits high energy density (59.34 Wh kg –1 ) and power density(150.73 W kg –1 ), as well as cycling stability maintaining more than 94% of its primary capacitance after 6000 charge–discharge cycles at a current density of 15 A g –1 . The perfect electrochemical performance of the above composites is attributed to both the particular 3D G/MWNTs interconnected structure which could enhance electric conductivity and the nitrogen-doping networks which could give the graphene/carbon nanotube surface large numbers of defects to support high performance cobalt oxide.