Structural, electronic properties, and quantum capacitance of B, N and P-doped armchair carbon nanotubes

• Exploration of variation in quantum capacitance of CNTs through doping N, B and P atoms.
• Quantum capacitance of CNTs is sensitive to impurities entered in carbon nanotubes.
• Maximum quantum capacitance of N-doped CNTs is achieved at the concentration range of 0.1–0.15.

Using DFT calculations, we study the structural parameters, electronic properties and quantum capacitance of N, B, and P-doped armchair carbon nanotubes (CNTs). Fermi level shifts towards conduction band and valence band in N- and B-doped CNTs, respectively. While in the case of P atom, despite having an extra valence electron than carbon, there is no shift in Fermi level. The results revealed from a symmetric capacitance enhancement in P-doped CNT and an asymmetric capacitance enhancement in B and N-doped CNTs. The greatest amount of quantum capacitance of N-doped (6, 6) CNT could be achieved at the concentration range of 0.1–0.15.