▎ 摘　　要

Ultrathin cobalt ferrite nanosheets have been successfully assembled on the surface of reduced graphene oxide (rGO) via only adjusting the volume ratio of ethanol and deionized (DI) water and a post calcination treatment. The perpendicular ultrathin cobalt ferrite nanosheets supported by rGO sheets (CoFe2O4 NSs@ rGO) can be obtained when the volume ratio of ethanol and DI water is 10:30. Correspondingly, the hierarchical porous films covering the total rGO sheets will be formed nanosheets. When evaluated as the electrodes for lithium ion batteries (LIBs) and supercapacitors (SCs), the resultant CoFe2O4 NSs@ rGO hybrids exhibit highly enhanced electrochemical performance. Even after 200 charge-discharge cycles at 400 mA g(-1), the electrodes as the anode material for LIBs still exhibit a reversible discharge capacity of 835.6 mAh g(-1). In addition, this electrode for SCs also exhibits specific capacitance of ca 1120 F g(-1) after 3000 cycles. These superior results imply that CoFe2O4 NSs with novel hybrid structure of rGO could potentially lead to an excellent electrochemical performance for energy storage.