▎ 摘　　要

A graphene/Co3O4/activated carbon (GCA) hybrid with excellent electrochemical properties for supercapacitance was successfully fabricated via a simple two-step hydrothermal method. The as-synthesized hybrid was examined by transmission electron microscopy (TEM), X-ray diffraction (XRD), and electrochemical characterization. The results confirmed that Co3O4 particles were homogeneously distributed between the graphene and activated carbon layers. The GCA 1:9 capacitor (GC:AC = 9:1) showed the best electrochemical property compared with other hybrid capacitors. The specific capacitance of the GCA 1:9 hybrid capacitor is 564 F g(-1) with activated carbon (AC) covering the outside of the graphene/Co3O4 (GC) layers. The specific capacitance of the GCA 1:9 was improved by 53.26% compared with the GC composite capacitor (368 F g(-1)) at 50 mA g(-1) in 7 M KOH. The GCA 1:9 also exhibits outstanding cycling property with 90.43% capacitance retention over 10000 cycles at a current density of 20 A g(-1). Moreover, it also achieved a high energy density of 35.7 W h kg(-1) at a power density of 235.5 W kg(-1), demonstrating that it is a promising candidate for supercapacitance.