Synthesis of boron-doped double-walled carbon nanotubes by the catalytic decomposition of tetrahydrofuran and triisopropyl borate

Boron-doped double-walled carbon nanotubes (DWCNTs) were produced by the catalytic decomposition of tetrahydrofuran and triisopropyl borate over a Fe-Mo/MgO catalyst at 900 °C. The synthesized B-doped DWCNTs had average outer and inner diameters in the range of 1.6-2.4 nm and 0.8-1.6 nm within the bundle, respectively. They had a larger interlayer spacing in the range of 0.36-0.39 nm, than did undoped DWCNTs. The B-C bonding evident from the B 1s signals in the X-ray photoelectron spectroscopy results indicated that highly coordinated boron atoms replaced the carbon atoms within the graphene sheet. As the triisopropyl borate concentration was increased from 0 to 2.5 M, the substituted boron concentration increased from 0.8 to 3.1 at.%. The results demonstrate that the substituted boron concentration in the hexagonal carbon lattices can be easily controlled by regulating the triisopropyl borate concentration.