Graphene-quantum-dots induced NiCo2S4 with hierarchical-like hollow nanostructure for supercapacitors with enhanced electrochemical performance

As a new class of zero-dimensional (0D) carbon nanomaterial, graphene quantum dots (GQDs) have attracted increasing attentions due to their unique properties of both graphene and quantum dots. In this paper, GQDs-decorated hierarchical-like hollow NiCo2S4 nanostructures are fabricated through simple two-step hydrothermal reactions. Compared with the bare NiCo2S4 nanowires, it is found that the surface morphology and internal structure have been changed with the introduction of the GQDs during the similar growth process. The unique nanostructures have resulted in better electrochemical performance for supercapacitors, such as good rate capability, high specific capacitance (678.22 F g(-1) at the current density of 0.2 A g(-1)) and enhanced cycling stability (94% retention after 5000 cycles), due to the lower impedance, larger specific surface area, more interspace and pathways for both ion diffusion and volume changes. These results show that the introduction of the GQDs during the fabrication process could be a feasible route to obtain novel nanostructures, and the GQDs decorated nanocomposites are promising for the development of next generation electrochemical devices. (C) 2018 Elsevier Ltd. All rights reserved.