Integrated carbon nanotube and triazine-based covalent organic framework composites for high capacitance performance

Abstract

As a rising class of crystallographic organic polymers, covalent-organic frameworks (COFs) have high specific surface areas, ordered pore structures, and designability, which exhibit broad application prospects in the energy storage sector. However, their low electrical conductivity hinders their potential use in supercapacitors. To improve the electrical conductivity, we introduced carboxylated multi-walled carbon nanotubes to obtain a series of carbon nanotube@COF composites by a facile one-pot method, in which 2D TFA-COFs are in situ grown on the surface of carboxylated multi-walled carbon nanotubes. Among them, the CNT@TFA-COF-3 composite exhibits good crystallinity, regular pores, excellent stability and a specific surface area of 1034 m² g⁻¹. As expected, as a capacitive electrode material, the CNT@TFA-COF composite shows improved electrochemical performance. Notably, the value of specific capacitance of the CNT@TFA-COF-3 composite (338 F g⁻¹) is about 8.5, 4.9, and 7.5 times higher than those of TFA-COFs, CNTs, and the CNT/TFA-COF physically mixed complex at a current density of 1.0 A g⁻¹, respectively. Furthermore, the CNT@TFA-COF-3 supercapacitor exhibits long-term cycle chemical stability and splendid rate capability even after 7000 charge–discharge cycles. The successful preparation of the CNT@TFA-COF-3 composite can provide new ideas for the construction of new COF-based composites and the development of new materials for energy storage.