Synthesis and remarkable capacitive performance of reduced graphene oxide/silver/nickel-cobalt sulfide ternary nanocomposites

Highly uniform ternary nanocomposites of reduced graphene oxide/silver/nickel-cobalt sulfide (RGO/Ag/NiCo2S4) are successfully prepared by an efficient two-step solution route. In the nanocomposites, Ag and NiCo2S4 nanoparticles with sizes of several nanometers are homogeneously anchored on the surface of RGO sheets. The RGO/Ag/NiCo2S4 nanocomposites are used as electrode materials for supercapacitors and their capacitive performance are investigated. It is found that their capacitive performances are remarkably affected by the Ag content. The RGO/Ag/NiCo2S4 nanocomposites exhibit excellent specific capacitance as high as 2438 F g−1 at the current density of 2.0 A g−1, good rate capability with a specific capacitance of 1410 F g−1 at the high current density of 20 A g−1, and high cycling stability with 85.4% capacitance retention after 2000 charge-discharge cycles at the current density of 10 A g−1. The enhanced capacitive performance can be attributed to the synergistic effect among NiCo2S4, Ag and RGO, in which RGO sheets serve as an ideal support matrix and Ag nanoparticles act as conductive channels. The remarkable capacitive performance of RGO/Ag/NiCo2S4 makes it a promising candidate for supercapacitor electrode materials.