N-doped reduced graphene oxide decorated NiSe2 nanoparticles for high-performance asymmetric supercapacitors

Abstract

This work reports the preparation of N-doped reduced graphene oxide decorated NiSe2 nanoparticles (N-rGO/NiSe2) in the presence of different amount of graphene oxide reactant by a simple two-step process, which contains hydrothermal preparation of Ni(OH)2 precursor and then solvothermal synthesis of N-rGO/NiSe2 composites with different content of N-rGO. The as-prepared N-rGO/NiSe2 composites is characterized by power X-ray diffraction, Raman spectroscopy, high-resolution X-ray photoelectron spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy and N2 adsorption–desorption isotherm. The results show that N-rGO acts as supporter of NiSe2 nanoparticles to prevent them from aggregation, leading to the increase in specific surface area and electrical conductivity of material. The optimized N-rGO/NiSe2 composite can deliver high specific capacitance of 2451.4 F g−1 at a current density of 1 A g−1. Using activated carbon (AC) as negative electrode and the optimized N-rGO/NiSe2 composite as positive electrode, an asymmetric supercapacitor is constructed. This fabricated asymmetric supercapacitor can work stably under the potential window of 0–1.6 V, and presents the maximum energy density of 40.5 Wh kg−1 at a power density of 841.5 W kg−1. Moreover, the N-rGO/NiSe2//AC asymmetric supercapacitor exhibits good cyclic stability.