Synergistic effect of NiS/g-C3N4 nanocomposite for high‐performance asymmetric supercapacitors

Fabricating a new electrode material with high capacitive aspects is critical to improving a high-performance energy storage device. The transition metal sulfide-based nanocomposite electrode materials are possible for the construction of high-performance hybrid supercapacitors owing to the large surface area and its peculiar Faradic battery-type charge storage behavior. In this work, the NiS/g-C3N4 hybrid was prepared through a one-pot hydrothermal method, and g-C3N4 was synthesized via a thermal method. The NiS/g-C3N4 shows the morphology of both sheet-like g-C3N4 and sphere-like NiS nanostructures. The compacted sheet and sphere structure of NiS/g-C3N4 hybrid composite shows outstanding electrochemical performance as a supercapacitor electrode. Consequently, the prepared NiS/g-C3N4 hybrid composite electrode materials reach their superior specific capacity (Cs) at 2661.25 C g−1 at 1 A g−1 in 3 M KOH aqueous electrolyte, which is comparatively higher than that of pure NiS spheres (722.50 C g−1 at 1 A g−1). The assembled NiS/g-C3N4//AC Hybrid device (HD) exhibited a maximum specific capacity of 181.8 C g−1 at 1 A g−1 and their energy density and power density of 53.09 W h kg−1 and 31537.5 W kg−1, respectively. The constructed NiS/g-C3N4//AC Hybrid device delivers outstanding cyclic retention of 95% after 10,000 cycles. The above results suggest that the NiS/g-C3N4 hybrid composite has good chemical stability, cyclic retention, and auspicious electrode material for the next generation of energy storage applications.