Needle-like Co3O4 anchored on the graphene with enhanced electrochemical performance for aqueous supercapacitors.
We synthesized the needle-like cobalt oxide/graphene composites with different mass ratios, which are composed of cobalt oxide (Co3O4 or CoO) needle homogeneously anchored on graphene nanosheets as the template, by a facile hydrothermal method. Without the graphene as the template, the cobalt precursor tends to group into urchin-like spheres formed by many fine needles. When used as electrode materials of aqueous supercapacitor, the composites of the needle-like Co3O4/graphene (the mass ratio of graphene oxide(GO) and Co(NO3)2·6H2O is 1:5) exhibit a high specific capacitance of 157.7 F g(-1) at a current density of 0.1 A g(-1) in 2 mol L(-1) KOH aqueous solution as well as good rate capability. Meanwhile, the capacitance retention keeps about 70% of the initial value after 4000 cycles at a current density of 0.2 A g(-1). The enhancement of excellent electrochemical performances may be attributed to the synergistic effect of graphene and cobalt oxide components in the unique multiscale structure of the composites.
Southwest University of Science and Technology , 643000 Mianyang, PR China.
Qun
Q
Guan
Jianli
J
Cheng
Bin
B
Wang
Wei
W
Ni
Guifang
G
Gu
Xiaodong
X
Li
Ling
L
Huang
Guangcheng
G
Yang
Fude
F
Nie