Metal–organic framework-derived hollow Co9S8 nanotube arrays coupled with porous FeCo–P nanosheets as an efficient electrode material for hybrid supercapacitors

Abstract

Cobalt sulfide (Co₉S₈) is a favorable material for supercapacitors, but its capacity and electrochemical cyclability are unsatisfactory, which inhibit its application. Therefore, it is extremely important to combine other materials with a higher theoretical capacity with Co₉S₈ nanostructures to enhance its electrochemical performance. Here, we report a binder-less electrode material composed of hollow Co₉S₈ nanotubes and porous FeCo–P nanosheets for a hybrid supercapacitor. The optimized sample is obtained through the electrodeposition of porous FeCo–P nanosheets on the metal–organic framework (MOF)-derived hollow Co₉S₈ nanotubes, which are supported on nickel foam (NF/CS@FCP). This special heterostructure assembled by porous FeCo–P nanosheets and hollow Co₉S₈ nanotubes presents improved availability of the redox electroactive sites, increased surface area, and facilitated electron–ion transfer for faradaic reactions in comparison with the single component. Due to its exclusive nanostructure and the synergistic effect of CS and FCP components, NF/CS@FCP presents an excellent capacity of 1590 C g⁻¹ at 1 A g⁻¹ and outstanding cyclability of 92.8% after 6500 cycles. When coupled with an activated carbon-based anode electrode (NF/AC), the hybrid device (NF/CS@FCP||NF/AC) unveils good energy/power density (66.6 W h kg⁻¹/846.5 W kg⁻¹). Therefore, this study highlights a promising strategy for the construction of the heterostructure for supercapacitors.