Ni(OH)<sub>2</sub> Templated Synthesis of Ultrathin Ni<sub>3</sub>S<sub>2</sub> Nanosheets as Bifunctional Electrocatalyst for Overall Water Splitting
Chunqiao Jin, Pengbo Zhai, Yi Wei, Qian Chen, Xingguo Wang, Weiwei Yang, Jing Xiao, Qianqian He, Qingyun Liu, Yongji Gong
Abstract
Abstract Ultrathin nickel (Ni)‐based sulfide nanosheets have been reported as excellent electrocatalysts for overall water splitting; however, the uncontrollability over thickness due to the nonlayered structure still hampers its practical application. Herein, a simple topochemical conversion strategy is employed to synthesize cobalt‐doped Ni 3 S 2 (Co‐Ni 3 S 2 ) ultrathin nanosheets on Ni foam. The Co‐Ni 3 S 2 nanosheets are controlled synthesized by using Co‐Ni(OH) 2 ultrathin nanosheets as templates with anneal and sulfurization treatment, showing exceptional electrocatalytic activity. This template‐assisted method can also be applied to obtain Ni, NiO, and NiP x nanosheets, providing a universal strategy to synthesize ultrathin nanosheets of nonlayered materials. The overall water splitting of this Co‐Ni 3 S 2 ultrathin nanosheets achieves a low voltage of 1.54 V at a current density of 10 mA cm −2 and high durability in 1 m KOH, comparable to the best performance of electrochemical water splitting ever reported. The detailed structural transformation of Ni‐based sulfides in the catalytic process and its mechanism are further explored both experimentally and theoretically.