Synthesis of Size‐Controllable NiCo<sub>2</sub>S<sub>4</sub> Hollow Nanospheres Toward Enhanced Electrochemical Performance
Lei Zhang, Haitao Zhang, Xiang Chu, Fangyan Liu, Chunsheng Guo, Weiqing Yang
Abstract
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.