Probing electrochemical charge storage of 3D porous hierarchical cobalt oxide decorated rGO in ultra-high-performance supercapacitor

Abstract

A 3D porous hierarchical Co 3 O 4 -reduced graphene oxide nanosheet (Co 3 O 4 -rGO) heterostructure is synthesized by a facile hydrothermal method . Microstructure analysis confirms the decoration of Co 3 O 4 hierarchical structures with an urchin-like spherical microstructure on rGO nanosheet with an average size of about 50 nm. The structural analysis reveals the formation of phase pure spinel Co 3 O 4 and reduced graphene showing their simultaneous existence in the composite. Raman spectroscopy confirms the successful reduction of graphite oxide to reduced graphene oxide and the effectual interaction between Co 3 O 4 and rGO matrix. The Co 3 O 4 -rGO composite electrode possesses utmost specific capacitance 688 F g −1 , due to effective ion transfer and slight agglomeration of Co 3 O 4 hierarchical structures on the surface of reduced graphene oxide. It is noteworthy that we have demonstrated a flexible solid-state supercapacitor device that exhibits an excellent performance suggesting the possible use of 3D porous hierarchical Co 3 O 4 -rGO composite in supercapacitor devices. Urchin-like spherical Co 3 O 4 decorated on rGO nanosheet delivered high specific energy of 72.6 Wh kg −1 corresponding to a specific capacitance of 688 F g −1 . • Hierarchical urchin-like Co 3 O 4 spherical microstructure decorated on rGO nanosheets is successfully synthesized. • The composite exhibits high capacitance of 688 F g −1 rate with excellent long-term stability. • Composite shows capacitance retention after 10,000 cycles with superb cycling stability (96%).