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Nano Research

Article Title

Controllable synthesis of Co3O4 from nanosize to microsize with large-scale exposure of active crystal planes and their excellent rate capability in supercapacitors based on the crystal plane effect

Keywords

Co3O4, mesoporous, single crystal, energy storage, supercapacitors

Abstract

ABSTRACT Co3O4 nanorods, nanobelts, nanosheets and cubic/octahedral nanoparticles have been successfully synthesized with tunable size from the nanoscale to the microscale, accompanied by a variation in the nature of the exposed crystal planes. The products are formed by thermal treatment of Co(CO3)0.5(OH)•0.11H2O nanorod, nanobelt, nanosheet and nanocubic/nanooctahedral precursors at 250 °C. Detailed characterization, including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photo- electron spectroscopy (XPS), and nitrogen adsorption and desorption isotherms, revealed that the as-prepared nanorods, nanobelts, and nanosheet Co3O4 samples are single crystalline and mesoporous in nature with a predominance of exposed high-energy (110) crystal planes. They exhibited excellent electrochemical properties in supercapacitors, showing higher capacitance and better rate capability than conventional cubic/octahedral Co3O4 nanoparticles having exposed low-energy (100) and (111) planes. No decay in capacitance was observed when the scan rate was increased from 5 mV/s to 100 mV/s, or from 1 A/g to 10 A/g. The maximum value of the specific capacitance was calculated to be 162.8 F/g and the capacitance retention reached as high as 90%. Their excellent performance in supercapacitors is believed to result from the large-area exposure of active (110) crystal planes. The Co3O4 nanosheets showed the best performance due to their larger surface area and ability to provide a better pathway for charge transfer, and are promising electrode materials for application in practical supercapacitors.

Graphical Abstract

Publisher

Tsinghua University Press

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