Controllable synthesis of hollow spherical nickel chalcogenide (NiS2 and NiSe2) decorated with graphene for efficient supercapacitor electrodes

Abstract

New carbon-loaded nickel chalcogenide electrode materials (NiS₂/GO and NiSe₂/rGO) have been synthesized through an easy-to-operate process: NiSe₂ was obtained based on NiS₂ hollow spheres, and was successfully synthesized with L-cysteine assistance under the hydrothermal method at 120 °C. GO of different mass fraction was added together with L-cysteine. The electrochemical performance of NiS₂/GO and NiSe₂/rGO has been greatly improved because the formation of a carbon-loaded layer effectively increased the specific surface area and reduced the charge transport resistance. Compared with pure NiS₂ and NiSe₂, NiS₂/GO and NiSe₂/rGO presented much better specific capacitance (1020 F g⁻¹ and 722 F g⁻¹ respectively at a current density of 1 A g⁻¹) and more superior rate capability (when the current density was raised to 5 A g⁻¹ the specific capacitance remained at 569 F g⁻¹ and 302 F g⁻¹). This work highlights the advantages of nickel compounds through a very simple experimental method, and contributes to providing a good reference for preparation of superior supercapacitor materials with high performance.