Influence of the nitrogen content on the electrochemical capacitor characteristics of vertically aligned carbon nanotubes

In this study, the electrochemical capacitor characteristics of vertically aligned carbon nanotubes (VACNTs) with different nitrogen content were investigated. The pristine VACNTs and nitrogen-doped VACNTs were synthesized by thermal chemical vapor deposition (CVD) with a mixture of C2H2 and NH3 gases. The content of nitrogen doped into VACNTs played an important role in enhancing the capacitance characteristics. With increasing the NH3 pressure, the nitrogen content of VACNTs increased. However, the capacitance did not increase with the increase in nitrogen content of VACNTs entirely. There was an optimal NH3 pressure for synthesizing the nitrogen-doped VACNTs to obtain the maximum capacitance. Furthermore, for the real practice of supercapacitor, the stability of capacitance was tested for 500 cycles. The results revealed that the nitrogen-doped VACNT was a promising supercapacitance device material.