Ag nanoparticles anchored reduced graphene oxide sheets@nickel oxide nanoflakes nanocomposites for enhanced capacitive performance of supercapacitors

Abstract

In this work, ternary nanocomposite of silver nanoparticles embedded on the surface of few layered reduced graphene oxide coated nickel oxide (Ag-rGO@NiO) was successfully fabricated as electrode material for high performance supercapacitor applications. NiO nanoflakes was prepared by hydrothermal route while coating of few layered rGO and subsequent silver anchoring was done by chemical methodology. The morphological analysis by scanning electron microscopy and transmission electron microscopy showed NiO nanoflakes coated by rGO/distributed on rGO substrate with scattered Ag nanoparticles. The elemental composition and distribution was confirmed by energy-dispersive X-ray (EDX) and Raman spectroscopy. The electrochemical measurements showed that the fabricated electrode of Ag-rGO@NiO is suitable electrode material and can enhance the capacitive performance of supercapacitors due to its high capacitive value (1230 Fg−1) in contrast to the binary rGO@NiO (337.5 F g−1) and bare NiO flakes (145 F g−1) at current density of 1 A g−1. The enhancement in the capacitive value of Ag-rGO@NiO composite was mainly attributed to the highly conductive rGO sheets and Ag nanoparticles where rGO sheets provided conductive path and Ag created new channels for the electron transfer. Furthermore, it also showed excellent cyclic stability as it retained 88.5 % of its initial capacitive value even after 3000 cycles as well as showed excellent energy density of (27.33 Wh kg−1) at power density (200.073 W kg−1).