The structure-stabilized Co3O4@Co9S8 core-shell nanorods synthesized by in-situ sulfuration of Co3O4 for high-performance supercapacitors

Abstract

In this work, we design and prepare Co3O4@Co9S8 core-shell nanorods by hydrothermal method, which the core is Co3O4 nanowires and the shell is Co9S8 nanosheets, and the nanorods interconnected between the core and shell are evenly distributed on nickel foam. More importantly, this hierarchical core-shell structure enables Co3O4@Co9S8 to possess large surface area and more efficient ion diffusion path when used as an electrode material, thereby providing a satisfactory specific capacity (it can reach 1545.1 C/g at 1 A/g), good rate performance (capacity value is 934 C/g at 20 A/g, the retention rate is 60%) and cycling stability (retention rate is still 81% after 1000 cycles). What's more, an asymmetric supercapacitor is prepared using activated carbon as the negative electrode and Co3O4@Co9S8 as the positive electrode and it shows the energy density of 26.1 Wh/Kg at power density of 871.6 W/Kg. Moreover, it has surprising stability, losing only 7.5% of its specific capacity after 10,000 cycles. As expected, the LEDs with different colors are successfully driven by as-prepared Co3O4@Co9S8//AC device, showing exciting application prospects of Co3O4@Co9S8 as an electrode material.