Carbon dot stabilized copper sulphide nanoparticles decorated graphene oxide hydrogel for high performance asymmetric supercapacitor

Abstract

A three-dimensional (3-D) porous structure was designed based on carbon dot (CD)-supported copper sulphide (CuS)-decorated graphene oxide (GO) hydrogel for using in a high-performance asymmetric supercapacitor device to improve the specific capacitance, cyclic stability and energy density of CuS as well as GO based supercapacitors. CD coated CuS (CuS@CD) decorated GO hydrogels (CuS@CD-GOH) were prepared by a simple hydrothermal reaction at 180 °C and optimized through different spectroscopic, diffraction, microscopic and electrochemical analyses. CD acted as a stabilizer for the CuS nanoparticles and help to bind strongly CuS nanoparticles with GO inside the 3-D hydrogel structure. The CuS@CD-GOH exhibited high specific capacitance of 920 F g−1 at a current density of 1 A g−1. The optimal CuS@CD-GOH was used as a positive electrode for the fabrication of asymmetric supercapacitor along with reduced GO as the negative electrode, which delivered the highest energy density up to 28 W h kg−1 along with long cycling life and retains up to 90% specific capacitance after 5000 cycles. The results are excellent in comparison to the reported CuS and composite GO hydrogel based supercapacitors. Thus, this work will provide a new insight of CuS and GO based composite 3-D structures for supercapacitor applications.