Dopamine-derived nitrogen-doped carboxyl multiwalled carbon nanotube-modified graphite felt with improved electrochemical activity for vanadium redox flow batteries.

Improving the electrochemical activity of electrodes is essential to the development of vanadium redox flow battery (VRFB). In this work, we prepared a novel electrode with the modification of nitrogen-doped carboxyl multiwalled carbon nanotubes using dopamine as an eco-friendly nitrogen source (carboxyl MWCNT@PDAt). Characterization and electrochemical measurements reveal that the synthesized carboxyl MWCNT@PDAt-modified graphite felt electrode (carboxyl MWCNT@PDAt/GF) exhibits excellent electrochemical performance toward VO/ reaction. Superior battery performance was obtained with the energy efficiency of 80.54% at a current density of 80 mA cm. Excellent durability of the carboxyl MWCNT@PDAt/GF electrode was confirmed by long-term charge/discharge tests. The enhanced reaction kinetics of VO/ is ascribed to the synergetic effect of oxygen and nitrogen containing groups on graphite felt surface and the presence of nitrogen-doped carboxyl multiwalled carbon nanotubes (MWCNT). The facile approach proposed in this paper provides a new route to the fabrication of electrode with excellent performance for VRFB.