Engineering active sites on nitrogen-doped carbon nanotubes/cobaltosic oxide heterostructure embedded in biotemplate for high-performance supercapacitors

Abstract

At present, both easy agglomeration of carbon nanotubes themselves and waste caused by chemical vapor deposition (CVD) have great pollution, which limits the use of carbon nanotubes (CNTs). A large number of hollow polyhedrons containing N-doped carbon nanotubes and Co3O4 nanoparticles (Co3O4 NPs) were well fabricated on a biotemplate by hydrothermal method, stirring method and pyrolysis process. The regular polyhedron was uniformly arranged on the external surface of diatomite with a natural porous structure, which aims to avoid the agglomeration of CNTs. The electrochemical testing result shows that the composite has promising electrochemical performance, which is embodied in a high specific capacity 894.6 F/g at 2 A/g, good rate performance and high cycling property. Finally, an assembled Co3O4 NP@CNTs@Diatomite//GR asymmetric supercapacitor has maximal energy density of 36.8 Wh/kg and maximal power density of 16,326.6 W/kg. Indeed, electrode design in this work provides an environmental synthesis idea for the decoration of CNTs on a certain substrate and displays an original electrode material based on diatomite.