Open ended nitrogen-doped carbon nanotubes for the electrochemical storage of energy in a supercapacitor electrode

• Open ended N-doped CNTs were prepared by a simple pyrolysis method followed by acid treatment technique.
• The acid treatment on N-doped CNTs leading to their ring opening.
• The open ended N-doped CNTs electrode shows superior electrochemical performance than as-synthesized N-doped CNTs.
• The electrochemical tests exhibited a maximum specific capacitance of 146 F g−1.

Open ended nitrogen-doped carbon nanotubes (N-doped CNTs) are synthesized by pyrolysis of acetylene/ammonia (C2H2/NH3) mixture over lanthanum nickel (LaNi5) alloy catalyst and subsequent 3M, HNO3:H2SO4 acid mixture treatment. Transmission electron microscopy and X-ray photoelectron spectroscopy evaluations of the acid treated N-doped CNTs reveal that the nanotubes possess an open ended morphology and oxidation of pyridinic–N groups, respectively. The resultant open ended N-doped CNTs tested as a supercapacitor electrode material by cyclic voltammetry and exhibits high specific capacitance of 146 F g−1.