Electrocapacitive performance of graphene/Co3O4 hybrid material prepared by a nanosheet assembly route

• α-Co(OH)2 with high crystallinity and well-defined hexagonal shape is prepared by a solvothermal treatment.
• ClO4−-α-Co(OH)2 can be exfoliated into Co(OH)2 nanosheets in formamide.
• RGO/Co3O4 hybrid material is prepared by a nanosheet assembled reaction and thermal treatment in controlled atmospheres.
• The RGO/Co3O4 (94.3%) electrode exhibits a high specific capacitance and excellent cycle stability.

Graphite oxide/Co(OH)2 layered composites are prepared by nanosheet assembling between the exfoliated Co(OH)2 and graphene oxide (GO) nanosheets. The subsequent thermal treatment of GO/Co(OH)2 composites in controlled atmospheres converts GO into reduced graphene oxide (RGO) and Co(OH)2 into Co3O4. The RGO/Co3O4 hybrid nanocomposites with different amounts of Co3O4 are thoroughly characterized, and their electrochemical properties as supercapacitor electrode are systematically investigated by cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy in the KOH electrolyte. In particularly, the RGO/Co3O4 hybrid composite with 94.3 wt% Co3O4 exhibits a high specific capacitance of 331 F g−1 at the current density of 5 A g−1, and shows the excellent electrochemical cycle stability with capacitance retention over 122% after 5000 continuous charge–discharge cycles. These outstanding capacitive performances make the RGO/Co3O4 hybrid nanocomposites one of the promising candidates for the supercapacitor electrode.

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