Synthesis of Size-Controllable NiCo2S4 Hollow Nanospheres Toward Enhanced Electrochemical Performance

Although the synthesis of novel nanostructured metal sulfides has been well established, further size-controllable optimization is still valuable to enhance their performance for various applications. Herein, a self-template method to size-controllably synthesize the hollow NiCo 2 S 4 nanospheres is reported. Uniformly monodisperse NiCo precursors with diameter widely ranging from 97 to 550 nm are controllably synthesized and subsequently transformed into hollow NiCo 2 S 4 nanospheres through in situ sulfidation. Smaller nanoparticles' diameter results in the hollow NiCo 2 S 4 nanospheres larger surface area and thinner shell thickness and hence provides much more electrochemical active sites as well as facilitate the ion and electron transfer. Consequently, the hollow NiCo 2 S 4 nanospheres—used as the electrode materials in supercapacitors—achieve 19% enhancement of specific capacity from 484.8 to 575.1 C g −1 through lowering the 42.5% diameter of hollow NiCo 2 S 4 nanospheres from 407 to 234 nm. Moreover, the hollow NiCo 2 S 4 nanospheres with 234 nm diameter exhibit superior rate capacity indicated by 49% capacity retention from 1 to 50 A g −1 and excellent cycling stability (77% after 2000 cycles). Furthermore, this method is a potentially general strategy in the size-controllable synthesis of the metal sulfides hollow nanostructures and results in the remarkable electrochemical applications.