Solvothermal synthesis and electrochemical performance in super-capacitors of Co3O4/C flower-like nanostructures

Novel three dimensional (3D) Co3O4/C flower-like nanostructures are synthesized via a facile solvothermal strategy. The samples are characterized by XRD, XPS, FT-IR, Raman, TG, SEM and HRTEM. The results show that the 3D flower-like nanostructures are consisted of numerous 2D nanosheets with the thickness of about 20 nm. The pseudocapacitive behaviors of Co3O4/C and bare Co3O4 flower-like nanostructures are investigated by cyclic voltammograms, galvanostatic charge–discharge and electrochemical impedance spectroscopy test. The results reveal that the Co3O4/C delivers a large specific capacitance of as high as 865 F g−1 and 330 F g−1 at 1 mV s−1 and 0.5 A g−1, according to CV and galvanostatic test, respectively; while the bare Co3O4 has a poor electrochemical performance, which exhibits specific capacitance of 131.7 F g−1 and 46.1 F g−1 at the same condition. The excellent electrochemical performance is attributed to the carbon present on the Co3O4 and the morphology, which possesses large surface area, unique flower-like nanostructures and low equivalent series resistance.