Self-assembled Co₃O₄nanoplatelets into micro-spheres via a simple solvothermal route: Structural and electrochemical properties

The self-assembled Co₃O₄microspheres made of nanoplatelets were prepared by a novel and simple solvothermal route. The crystal structure and morphology were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively. The FESEM shows that the average diameter of the microspheres is about 8 μm and the thickness of individual nanoplatelets is 30–70 nm. X-ray photoelectron spectroscopy (XPS) studies reveal two strong peaks appearing at 780.6 and 797.0 eV, corresponding to the core level electrons for Co 2p_3/2and Co 2p_1/2, which are characteristic XPS peaks of Co₃O₄phase. The electrochemical properties of cobalt oxide nanoplatelets modified electrodes were scrutinized by cyclic voltammetry (CV) and charge-discharge profile with cycles, showing a stable reversible capacity of 620 mA h/g after 40 cycles.