Design and construction of hollow metal sulfide/selenide core-shell heterostructure arrays for hybrid supercapacitor.

Transition metal sulfides and selenides are common electrode materials in supercapacitors. However, the slow redox kinetics and structural collapse during charge-discharge cycles of single-component materials have impeded their electrochemical performance. In this study, hollow CoS nanotubes were synthesized through a rational morphology design approach. Subsequently, NiSe or CoSe was electrodeposited onto the CoS nanotubes, yielding two core-shell heterostructure arrays, namely, NiSe@CoS and CoSe@CoS. By fully leveraging the advantages and synergistic effects of these dual-phase heterostructures, the NiSe@CoS and CoSe@CoS configurations demonstrated outstanding areal capacitances of 12.54 F cm and 9.61 F cm, respectively, at 2 mA cm. When integrated with activated carbon in hybrid supercapacitors, the NiSe@CoS//AC and CoSe@CoS//AC devices exhibited excellent energy storage performance, with energy densities of 0.959 mW h at 1.681 mW and 0.745 mW h at 1.569 mW, respectively. Additionally, these hybrid supercapacitors demonstrated remarkable cycling stability, with capacitance retention of 87.5% and 89.5% after 5000 cycles for NiSe@CoS//AC and CoSe@CoS//AC, respectively. This study provides a novel approach to the synthesis of multiphase core-shell heterostructures based on metal sulfides and selenides, opening new avenues for future research.