Direct synthesis of nitrogen-doped narrow-diameter carbon nanotubes through floating-catalyst chemical vapor deposition with high hydrogen flow rate

The precise control of substitutional nitrogen (N) doping into a carbon nanotube (CNT) lattice is key to tuning their unique one-dimensional electronic properties. Here we report a direct synthesis of high-quality N-doped single-wall CNTs (N-SWCNTs) with ∼1 nm in diameter using a floating-catalyst chemical vapor deposition under a high flow rate of hydrogen as a carrier gas. The high hydrogen flow rate enhances the total N content in the CNT lattice. The N-SWCNTs exhibit an n-type doping behavior induced by enriched graphitic-N as confirmed by Raman analysis. Our finding will be beneficial to tailoring the doping state of N-SWCNTs.