Scalable Fabrication of NiCo₂S₄/g-C₃N₅ Nanohybrid: A High-Performance Electrode Material for Supercapacitor Applications

The growing reliance on sustainable energy resources demands the development of efficient energy storage devices. Supercapacitors offer a viable solution, offering superior charge-discharge rates and excellent long-term cyclic stability over conventional devices. This study investigates the potential of emerging graphitic carbon nitride (g-C₃N₅) as a supercapacitor electrode material, and a comparison was made by integrating it with the promising nickel cobalt sulfide (NiCo₂S₄) through a facile indirect-hydrothermal process. The g-C₃N₅ and NiCo₂S₄ exhibit a specific capacitance of 474.28 and 668 Fg^-1 respectively, while their nanocomposite exhibits specific capacitance of 1405 Fg^-1 at 1 Ag^-1. The improved electrochemical performances can be attributed to the uniform distribution of plate-like NiCo₂S₄ with sheet-like g-C₃N₅ within the nanocomposite, as confirmed in SEM and HR-TEM analyses. This results in the increased specific surface area, as revealed from the BET study, thereby offering more accessible active sites compared to the pristine materials. Furthermore, the integrated property of extended π conjugated, nitrogen-rich framework of g-C₃N₅ with the excellent electrical conductivity of NiCo₂S₄, facilitates improved charge transfer kinetics in the prepared nanocomposite. The asymmetric device fabricated using the nanocomposite exhibits a high energy density of 45.258 Whkg^-1 at a power density of 800 Wkg^-1 with enhanced cyclic stability, retaining 92% over 5000 cycles. These remarkable properties make NiCo₂S₄/g-C₃N₅ a promising electrode for supercapacitor applications.