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

Abstract

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 Co₉S₈ nanotubes were synthesized through a rational morphology design approach. Subsequently, NiSe₂ or Co_0.85Se was electrodeposited onto the Co₉S₈ nanotubes, yielding two core–shell heterostructure arrays, namely, NiSe₂@Co₉S₈ and Co_0.85Se@Co₉S₈. By fully leveraging the advantages and synergistic effects of these dual-phase heterostructures, the NiSe₂@Co₉S₈ and Co_0.85Se@Co₉S₈ 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 NiSe₂@Co₉S₈//AC and Co_0.85Se@Co₉S₈//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 NiSe₂@Co₉S₈//AC and Co_0.85Se@Co₉S₈//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.