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 Co 9 S 8 nanotubes were synthesized through a rational morphology design approach. Subsequently, NiSe 2 or Co 0.85 Se was electrodeposited onto the Co 9 S 8 nanotubes, yielding two core-shell heterostructure arrays, namely, NiSe 2 @Co 9 S 8 and Co 0.85 Se@Co 9 S 8 . By fully leveraging the advantages and synergistic effects of these dual-phase heterostructures, the NiSe 2 @Co 9 S 8 and Co 0.85 Se@Co 9 S 8 configurations demonstrated outstanding areal capacitances of 12.54 F cm -2 and 9.61 F cm -2 , respectively, at 2 mA cm -2 . When integrated with activated carbon in hybrid supercapacitors, the NiSe 2 @Co 9 S 8 //AC and Co 0.85 Se@Co 9 S 8 //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 2 @Co 9 S 8 //AC and Co 0.85 Se@Co 9 S 8 //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.