Co ₃ O ₄ nanocrystals grown on graphene nanosheets for high-performance supercapacitor with excellent rate capability

Abstract: Co ₃ O ₄ nanocrystals grown on graphene nanosheets (GNSs) were synthesized through a facile microwave hydrothermal method. The morphological and crystalline changes of Co ₃ O ₄ nanocrystals during the microwave hydrothermal treatment are characterized by FE-SEM and XRD. Different morphologies of Co ₃ O ₄ /GNSs are obtained by controlling the microwave hydrothermal temperatures and time. The particle-slice Co ₃ O ₄ /GNSs exhibits the specific capacitance of 736 F g ⁻¹ at a current density of 9 A g ⁻¹ and 659 F g ⁻¹ at a high current density of 32 A g ⁻¹ (~97% capacitance retention at 4.5 A g ⁻¹ and ~89% capacitance retention at 9 A g ⁻¹ ). Therefore, the anode material with high rate capability and excellent cycle stability could be promising for high-performance supercapacitor. [Figure not available: see fulltext.].