A nanocrystalline structured NiO/MnO2@nitrogen-doped graphene oxide hybrid nanocomposite for high performance supercapacitors

Abstract

Nitrogen doped graphene oxide (NGO) has been widely used to investigate active electrode materials for high-performance supercapacitors. NGO has attracted wide attention due to the efficient method of doping with GO, which can increase the electron mobility, leading to desirable electrochemical properties. Therefore, in the present study we focus on the ternary hybrid composite of NiO/MnO₂@nitrogen-doped graphene oxide, which was synthesized via a hydrothermal process. The synthesized hybrid nanocomposite was characterized using Raman spectra, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), and field-emission transmission electron microscopy (FE-TEM). The structural and morphological studies of the hybrid nanocomposite shows its nanocrystalline behaviour. The nanocrystalline hybrid composite exhibited a high specific capacitance of 1490 F g⁻¹ at a current density of 0.5 A g⁻¹, energy density of 477 W h kg⁻¹, and power density of 1844 W kg⁻¹, together with good rate capability and cyclic stability. The results show a good specific capacitance retention of ∼98% after 2000 continuous charge–discharge cycles; this indicates that the hybrid nanocomposite can be a promising electroactive material for supercapacitors. The improved performance of the NiO@MnO₂/NGO electrode structure means that it offers an effective way to fabricate high performance supercapacitors.