Nitrogen-doped graphene quantum dots embedding CuCo-LDH hierarchical hollow structure for boosted charge storage capability in supercapacitor

The nanostructure optimization of layered double hydroxide (LDH) can effectively alleviate fragile agglomerated problems. Herein, nitrogen-doped graphene quantum dots (NGQDs) embedded in CuCo-LDH hierarchical hollow structure is synthesized by hydrothermal and impregnation methods. The electrochemical results show that the ordered multi-component structure could effectively inhibit the aggregation and layer stacking. At the same time, the hierarchical structure establishes new electron and ion transfer channels, greatly reducing the resistance of interlayer transport and accelerating the diffusion rate of electrolyte ions. Besides, NGQDs have both good electrical conductivity and abundant active sites, which can further improve the electron transmission rate and effectively strengthen the energy storage capacity of the material. Therefore, the large specific capacity of 1009 F g- 1 can be displayed at 1 A g-1. The energy density of the assembled carbon cloth (CC)@CuCo-LDH/NGQDs// activated carbon (AC) device can reach 58.6 Wh kg-1 at 850 W kg-1. Above test results indicate that CC@CuCo-LDH/NGQDs//AC devices exhibit stable multi-component hierarchical structure and excellent electrical con-ductivity, which provides an effective strategy for enhancing the electrochemical characteristics of asymmetric supercapacitors.