Controllable Synthesis of Mesoporous Co3O4 Nanostructures with Tunable Morphology for Application in Supercapacitors

Novel and complex mesoporous 2D and 3D architectures of the oxide semiconductor Co3O4, including nanosheets, nearly monodisperse microspheres that are self-assembled from nanosheets, and copper-coin-like nanosheets, have been synthesized through a facile binary-solution route and sequential thermal decomposition at atmospheric pressure. The influence of different reaction conditions on the morphology of the products has been discussed in detail. The results revealed that the volume ratio of H2O and ethanolamine (EA) play a crucial role in the morphology of the precursor. The thermal decomposition of the corresponding precursor leads to the formation of the mesoporous structure. The products have been characterized by X-ray diffraction techniques, field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and Raman spectroscopy. The electrochemical properties of the Co3O4 electrodes were investigated by cyclic voltammetry (CV) and galvanostatic charge-discharge measurements. The electrochemical experiments revealed that the specific capacitance of the Co3O4 nanosheets was higher than that of the Co3O4 microspheres in a KOH electrolyte solution (3 M). Furthermore, the Co3O4, nanosheet electrodes exhibited good rate capabilities, and maintained 93% of the initial capacity at a current density of 5 mA cm(-2) in a KOH (3 M) electrolyte solution. The results show that Co3O4 nanosheets might have potential applications as electrode materials for supercapacitors.