Fabrication of VO2(B) hybrid with multiwalled carbon nanotubes to form a coaxial structure and its electrochemical capacitance performance

Abstract

A coaxial-structured hybrid material of vanadium dioxide (VO2(B)) and multiwalled carbon nanotubes (MWCNTs) is synthesized by a facile sol–gel method assisted with freeze-drying process. A few layers of VO2(B) sheath are firmly coated on the CNTs surfaces, resulting in the formation of network morphology with abundant pores and good electric conductivity. This VO2(B)/CNTs composite for the first time is employed as a supercapacitor electrode material, demonstrating better specific capacitance and superior rate capability than the individual components alone. A specific capacitance of 250Fg−1 was obtained in 1M Na2SO4 solution at a current density of 0.5Ag−1, with a capacitance retention up to 71% when the current density was increased to 10Ag−1. The excellent electrochemical performance can be ascribed to its unique coaxial-structure with the VO2(B) as the shell and the CNTs as the core, as a result of which the CNTs core offers fast electron transport due to its high electronic conductivity, while the VO2(B) shell provides large faradic pseudocapacitance in this composite material. We believe that the unique configuration and improved electrochemical performance may exhibit huge potential for VO2(B) as a promising supercapacitor material.