Self-assembled Ni/NiO/RGO heterostructures for high-performance supercapacitors

Abstract

A nano-sized nickel/nickel oxide/RGO (Ni/NiO/RGO) nano-hybrid was generated successfully by using a facile and green sol–gel approach, with the reduced graphene oxide as an effective component, for developing a high-efficiency electrode material with super-capacitance. In the novel hierarchical nano-composite, the combination of metallic nickel interfaced with the nickel oxide was created by the reduction of a nickel nitrate precursor with the carbon of the reduced graphene oxide surface, during the thermal treatment in nitrogen. The electrochemical performances of the Ni/NiO/RGO composite were measured through cyclic voltammetry tests and galvanostatic charge–discharges, as a supercapacitor material. Due to the higher conductivity and synergistic effect, the new hybrid delivered a high specific capacitance of 1027.27 F g⁻¹ at the charge/discharge current density of 2 A g⁻¹, and 720 F g⁻¹ at 20 A g⁻¹. After 1000 uninterrupted cycles at 5 A g⁻¹, the high specific capacitance value can be still stabilized, and kept at 92.95% of the initial value of the specific capacitance for Ni/NiO/RGO. This new nano composite with RGO and Ni/NiO exhibits great promise as an electrode material for supercapacitors.