Graphene In Situ Coated High‑Oxygen Vacancy Co_3O_(4−x) Sphere Composites for High‑Stability Supercapacitors

摘要

In this paper, the graphene in situ coated Co_3O_4 core-shell heterogeneous composites have been facilely fabricated via microwave plasma-enhanced chemical vapor deposition method. The graphene thin-shell-layer-covered Co_3O_(4−x) particles were revealed by FE-SEM, XRD, XPS and Raman spectra. And the ratio of Co~(2+)/Co~(3+) is adjusted, and abundant surface oxygen vacancies are created by the microwave plasma etching, which can contribute to the improvement of electrochemical performance for the Co_3O_4/graphene core-shell composites. Results present that the graphene in situ coated Co_3O_(4−x) has a specific capacitance of 192.8 F g~(−1) under the current density of 0.5 A g~(−1), which is 4.5 times than that of the original Co_3O_4 sphere. Meanwhile, the core-shell heterogeneous composite displays excellent cyclic stability with ~ 98.5% specific capacitance retained after 20,000 cycle tests.