Synthesis of wool ball-like copper sulfide nanospheres embedded graphene nanocomposite as electrode for high-performance symmetric supercapacitor device

Graphene oxide is widely employed in electrochemical applications, whereas CuS is well-known semiconducting material utilized for the photocatalytic application. In an effort to utilize their advantage for desirable electroactive materials in energy conversion and storage applications, the present work demonstrates the preparation of CuS/Graphene nanocomposites by a facile hydrothermal approach. The structural studies were employed to confirm the nanocomposite formation. The scanning electron microscope and transmission electron microscope images revealed that the CuS nanospheres are homogeneously decorated over the surface of the graphene sheets in CuS/graphene nanocomposite. FT-Raman analysis showed the change of I-D/I-G ratio indicated the reduction graphene oxide to graphene. The FTIR spectra reaffirm that upon CuS/graphene nanocomposite formation, the basal graphene oxide reduced to graphene. The optical properties of the prepared materials were investigated by UV-Vis absorption spectra. The CuS/G nanocomposite possesses high surface area, which is confirmed by the BET analysis. The electrochemical performance assessed by cyclic voltammetry points out the remarkable enhancement of specific capacitance of the nanocomposite due to the interaction between CuS nanosphere and graphene sheets. The composite device exhibits a maximum specific capacitance of 197.45 Fg(-1) at 5 mV s(-1). In addition, the charge-discharge dynamics of CuS/G nanocomposite has been evaluated. The outstanding cyclic stability has been obtained from cyclic voltammetry, which is 90.35% retention after 1000 cycles at 5 A g(-1). The composite material has high specific energy 28.4 W h kg(-1) as well as high specific power 2.5 kW kg(-1). These results indicate that the prepared CuS/G nanocomposite materials could be suitable candidate for high-performance supercapacitor device.