Controllable synthesis of hollow spherical nickel chalcogenide (NiS 2 and NiSe 2 ) decorated with graphene for efficient supercapacitor electrodes.

New carbon-loaded nickel chalcogenide electrode materials (NiS 2 /GO and NiSe 2 /rGO) have been synthesized through an easy-to-operate process: NiSe 2 was obtained based on NiS 2 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 NiS 2 /GO and NiSe 2 /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 NiS 2 and NiSe 2 , NiS 2 /GO and NiSe 2 /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.