Direct Growth of Oxygen Vacancy-Enriched Co3O4 Nanosheets on Carbon Nanotubes for High-Performance Supercapacitors

摘要

Ultrathin Co_(3)O_(4) nanosheets (NSs) with abundant oxygen vacancies on conductive carbon nanotube (CNT) nanocomposites (termed as Co_(3)O_(4)-NSs/CNTs) are easily achieved by an effective NaBH_(4)-assisted cyanogel hydrolysis strategy under ambient conditions. The specific capacitance of Co_(3)O_(4)-NSs/CNTs with 5% CNT mass can reach 1280.4 F g~(–1) at 1 A g~(–1) and retain 112.5% even after 10?000 cycles, demonstrating very high electrochemical capability and stability. When assembled in the two-electrode Co_(3)O_(4)-NSs/CNTs-5%//reduced graphene oxide (rGO) system, a maximum specific energy density of 37.2 Wh kg~(–1) (160.2 W kg~(–1)) is obtained at room temperature. Ultrathin structure of nanosheets, abundant oxygen vacancies, and the synergistic effect between Co_(3)O_(4)-NSs and CNTs are crucial factors for excellent electrochemical performance. Specifically, these characteristics favor rapid electron transfer, complete exposure of the active interface, and sufficient adsorption/desorption of electrolyte ions within the active material. This work gives insights into the efficient construction of two-dimensional hybrid electrodes with high performance for the new-generation energy storage system.