Hierarchical nickel sulfide hollow spheres for high performance supercapacitors

Hierarchical NiS hollow spheres assembled from ultrathin nanosheets are synthesized by an efficient template-engaged conversion method. Silica nanospheres were used as templates, and SiO₂@nickel silicate core-shell nanostructures were first prepared. In the presence of Na ₂S, the nickel silicate shell completely transformed into NiS nanosheets via a hydrothermal treatment, accompanied by the total dissolution of the inner SiO₂ core. This gives rise to uniform hollow nanospheres whose shells are assembled from ultrathin NiS nanosheets. In virtue of the large surface area and enhanced structural stability, the as-prepared NiS hollow spheres exhibit excellent electrochemical performance as electrode materials for supercapacitors.