Sequential partial ion exchange synthesis of composite Ni3S2/Co9S8/NiSe nanoarrays with a lavender-like hierarchical morphology

A series of hierarchical nanoarrays with a lavender-like structure was synthesized via a facile in situ hydrothermal method by sequential partial ion exchange. Hierarchical Ni@Ni3S2 nanoarrays that were partially surrounded with nanoflakes were first fabricated by simultaneously using Ni foam as a template and as a source. The hierarchical structure was composed of one-dimensional rods combined with two-dimensional nanoflakes. Furthermore, Co and Se ions, as the beneficial cation and anion, were successfully introduced into the hierarchical Ni@Ni3S2 material by sequential partial ion exchange. This reaction formed Ni@Ni3S2/Co9S8 and Ni@Ni3S2/Co9S8/NiSe composite multilevel electrodes with structures that were similar to those of the parent materials. All the as-prepared materials were assembled into asymmetric supercapacitor devices to explore their electrochemical performance. Compared with single-component Ni@Ni3S2, the Ni@Ni3S2/Co9S8/NiSe//active carbon device exhibited a better rate performance of 78.93 F g(-1) at a current density of 1 A g(-1) (retaining 75% from 1 A g(-1) to 10 A g(-1)). This device still delivered an energy density of 17.75 Wh kg(-1) even at a high power density of 1945.2 W kg(-1). This finding demonstrated that Ni@Ni3S2/Co9S8/NiSe is a promising electrode material for supercapacitors.