Improving the charge kinetics through in-situ growth of NiSe nanoparticles on g-C3N4 nanosheets for efficient hybrid supercapacitors

Nickel selenide (NiSe) has been a promising positive electrode for hybrid supercapacitors due to its multiple oxidation states, tunability, and high specific capacity. However, sluggish ion transfers and particle agglomeration hamper its electrochemical performance. In the present study, we have grown NiSe nanoparticles on two-dimensional (2D) graphitic carbon nitride (g-C3N4) nanosheets to realize three-dimensional (3D) architecture. The 2D support, high nitrogen content, and features of g-C3N4 enhanced the specific capacity of the NiSe/g-C3N4 nanocomposite material. The resulting nanocomposite shows a specific capacity of 320 mA h g−1 at a current density of 1 A g−1, which is considerably higher than pristine NiSe. Later, the hybrid supercapacitor (HSC) device was fabricated using NiSe/g-C3N4 composite as positive and activated carbon (AC) as negative electrodes. The cell delivered an energy density of 52.5 Wh kg−1 at a power density of 1488 W kg−1 with excellent cyclic stability of 84.9% over 8000 cycles. The electrochemical performance enhancement corresponds to a 3D structure, high electrochemical active sites, and improved charge transportation at the electrode/electrolyte interface. Thus, the present work offers an easy approach and architectural design for high-performance HSC.