Incorporation of Carbon Quantum Dots for Improvement of Supercapacitor Performance of Nickel Sulfide

[Image: see text] A facile hydrothermal method is adopted for the synthesis of hierarchical flowerlike nickel sulfide nanostructure materials and their composite with carbon quantum dot (NiS/C-dot) composite. The composite material exhibited good performance for electrochemical energy-storage devices as supercapacitor with a specific capacity of 880 F g(–1) at a current density of 2 A g(–1). The material remained stable up to the tested 2000 charge–discharge cycles. Carbon quantum dots of size 1.3 nm were synthesized from natural sources and the favorable electronic and surface property of C-dots were utilized for improvement of the supercapacitor performance of NiS. The results from Tafel analysis, double-layer capacitance, and the impedance measurement reveal that the incorporation of C-dots inside the NiS matrix has improved the charge-transfer process, which is mainly responsible for the enhancement of the supercapacitive property of the composite materials.