▎ 摘　　要

In this paper, the MnO2/three-dimensional carbon nanotubes-graphene nanocomposite was synthesized on Cu foil substrate by chemical vapor deposition and subsequent thermal decomposition of manganese acetyllacetonate precursors. The nanocomposite material was directly used as a binder-free electrode to investigate the supercapacitive performance. The results indicate that the appropriate defects and MnO2 nanoparticles are introduced simultaneously into the carbon nanotubes-graphene architecture in one-step. The specific capacitance of MnO2/three-dimensional carbon nanotubes-graphene/Cu electrode is up to 365 F g(-1) at a current density of 1 A g(-1) in 1.0 M Na2SO4 solution, which is 9 times higher than that of electrode without MnO2 modification. After 1000 cycles at 1 A g(-1), the capacity retention is still maintained at 97.0%, suggesting potential applications in high-performance energy storage devices. The excellent electrochemical performances of nanocomposite electrode can be attributed to the significantly synergistic effects between the lasting electronic conductivity of three-dimensional carbon nanotubes-graphene/Cu with the appropriate defects and the pseudocapacitance of the MnO2 nanoparticles. (C) 2019 Elsevier B.V. All rights reserved.