Cu2O/Cu@C nanosheets derived from one novel Cu (II) metal-organic framework for high performance supercapacitors

Abstract Unique nanostructures could lead to extraordinary electrochemical energy storage performance. Cu2O/Cu@C nanosheets were successfully synthesized from one novel Cu (II) metal-organic framework (Cu-MOF) with a three-dimensional structure, which was assembled by Cu (II), 4-(pyridine-4-yl) phthalic acid and 1,4-bis (benzoimidazo-1-ly) benzen. The Cu (II) was in-situ reduced to form Cu2O/Cu nanoparticles by calcination, which were homogeneously anchored onto carbon sheets. The Cu2O/Cu@C nanosheets exhibit a high specific surface area (336.3 m2 g−1) and large total pore volume (3.41 cm3 g−1), which inherit the original morphology and structure of the Cu-MOF. The nanosheets possess a specific capacitance of 665 F g−1 at a current density of 0.5 A g−1, which is higher than that of Cu-MOF (320 F g−1). Meanwhile, the capacitance retention remains 53.5% with the increasing current density from 0.5 to 5 A g−1, and 82.5% after 5000 cycles at a current density of 0.5 A g−1, which indicate their outstanding rate capability and cycling stability. Further, the as-assembled Cu2O/Cu@C//AC asymmetric supercapacitor achieves the maximum energy density of 38.6 Wh kg−1 at the power density of 466.5 W·kg−1. These excellent electrochemical performances indicate that the Cu2O/Cu@C nanosheets have potential applications in energy storage.