Nitrogen- and oxygen-doped multi-walled carbon nanotubes for supercapacitor with ionic liquid-based electrolyte

Nitrogen-doped multi-walled carbon nanotubes (CNTs) containing 2.2 at.% of nitrogen were produced by hydrothermal treatment of oxygen-doped CNTs with urea and tested as electrode material for the supercapacitor with ionic liquid electrolyte. Cyclic voltammetry measurements showed a beneficial effect of nitrogen doping on the capacitance behavior of CNTs resulted from both the changes in their electronic structure and improved interaction between the electrode surface and electrolyte ions. The specific capacitance of nitrogen-doped CNTs was 2.6 times higher than that of pristine ones.