Facile Fabrication of Co3O4@C@Tnas Heterojunction Composites with Enhanced Electrochemical Performance for Supercapacitors
amorphous carbon and Co3O4 nanoparticles was prepared in this paper. Carbon-doped TNAs (C@TNAs) were fabricated by anodic oxidation of a pure titanium sheet in an aqueous
solution containing 0.25M NH4F and 7vol% H2O directly, then followed by annealing
the prepared TNAs samples in the Ar atmosphere, with the residual ethylene glycol absorbed on the
TNAs wall during anodization as the carbon source. The C@TNAs were chosen as the 3D framework
with larger surface area, easier access for the ions in the solution as well as the highly chemical
stability, and the amorphous carbon could enhance the electric conductivity of TNAs.
Co3O4 nanoparticles with the size of less than 15 nm were synthesized via the simple process of
chemical bath deposition of cobalt acetate aqueous solution, which was as a result of the hydrolysis
of Co2+ and simultaneously heterogeneous growth of Co3O4 nanoparticles on both the outer and
inner surfaces of C@TNAs. The morphology, component and electrochemical property of
Co3O4@C@ TNAs were characterized by field emission scanning electron microscope (FESEM),
transmission electron microscope (TEM), X-ray diffraction (XRD), Raman spectrum, X-ray photoelectron
spectroscopy (XPS), cyclic voltammetry (CV) and amperometry charge and discharge (CD), respectively.
The influence of amorphous carbon on promoting electrochemical properties was discussed in this paper
through comparing the CV of Co3O4 @ TNAs and Co3O4@C@ TNAs. After doped with amorphous carbon,
a maximum specific capacitance of 689 F g-1 has been obtained in 2M KOH aqueous electrolyte at current
density of 1 A g-1 with a potential window from 0 to 0.45 V (vs. Ag/AgCl). Furthermore, the specific
capacitance retains 84 % based on the initial capacitance after 4000 cycles under high current density of
10 A g-1, revealing the excellent long term electrochemical stability of the sample even at high cycling rate.
Co3O4@C@TNAs heterostructure composites will hode promise for one of the best electrode systems for high