The synergistic effect of carbon nanotubes and graphitic carbon nitride on the enhanced supercapacitor performance of cobalt diselenide-based composites

Abstract

Recently, transition metal selenides have been investigated extensively as promising electrode materials for high-performance supercapacitors. Herein, multi-component CoSe₂/CNTs@g-C₃N₄ composites are prepared using a two-step hydrothermal method by incorporating one-dimensional CNTs and two-dimensional g-C₃N₄ nanosheets to form a network-like structure. The CoSe₂/CNTs@g-C₃N₄ composite with a mass ratio of 1 : 3 (CNTs to g-C₃N₄) shows an ultra-high specific capacity of 445.4 mA h g⁻¹ (3563.0 F g⁻¹) at 1 A g⁻¹, which is more than 2 times that of pure CoSe₂. The assembled asymmetric supercapacitor based on CoSe₂/CNTs@g-C₃N₄ delivers a high energy density of 77.1 W h kg⁻¹ at 850 W kg⁻¹. The striking capacitive performance is ascribed to the multi-dimensional synergistic contribution of two kinds of carbon materials to the electric conductivity and spatial structure of the composites, involving the improved charge transfer due to connecting g-C₃N₄ and the active CoSe₂ by the high conductive CNT bridges, and the short ion diffusion pathways on the porous carbon framework constructed by g-C₃N₄ nanosheets with the assistance of CNTs.