Interlaced WO3-carbon nanotube nanocomposite electrodeposited on graphite as a positive electrode in vanadium redox flow battery

A novel kind of tungsten trioxide-multi walled carbon nanotubes (WO3-MWCNTs) nanocomposite electrode as a positive electrode in vanadium redox flow battery has been developed in this paper. The electrode was fabricated by electrochemical reduction of functionalized MWCNTs and W2O11− 2 onto graphite. The morphology studies showed that the obtained electrode has many interlaced WO3-MWCNTs nanorods on the surface of graphite. Electrochemical performance toward the VO2 +/VO2+ redox reactions was evaluated by cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry procedures in a three electrode half-cell. Results showed that the WO3-MWCNTs/graphite electrode exhibit high peak current density, small peak potential difference and low charge transfer resistance toward the [VO]2 +/[VO2]+ redox reactions in contrast to graphite, WO3/graphite and MWCNT/graphite electrodes, confirming good electrocatalytic activity and kinetic reversibility of the modified electrode.