Ultrathin and Highly Crystalline Co 3 O 4 Nanosheets In Situ Grown on Graphene toward Enhanced Supercapacitor Performance

Effective design of an electrode material is essential for energy storage and conversion of supercapacitor. Herein, a well‐designed architecture of ultrathin and highly crystalline Co 3 O 4 nanosheets (NSs) with a thickness of 2–3 nm are grown in situ on reduced graphene oxide (RGO) via a hydrothermal route and a subsequent calcination process. During synthesis, graphene oxide (GO) affects the growth of precursor. The Co 3 O 4 /RGO composites are employed as electrode material of supercapacitor with the aim of achieving the high electrochemical performance. The results indicate that Co 3 O 4 /RGO‐2 electrode (the mass ratio of CoCl 2 to GO is 10:1) has the best performance with a specific capacitance of 3344.1 F g −1 at a current density of 1.25 A g −1 , fine rate capability, and retention capacity of 87.9% even after 6000 cycles at 10 A g −1 . Such excellent performance is ascribed to the synergistic effects of ultrathin and highly crystalline Co 3 O 4 NSs and its interacting model with RGO. This ultrathin sheet–sheet architecture will provide a promising for electrochemical fields.