Preparation of bamboo-like carbon nitride nanotubes, spheres, and study of their structural, morphological and optical properties

A large-scale bamboo-like carbon nitride nanotube powder has been prepared on Nichrome60 and quartz substrates at 800 °C by Chemical Vapor Deposition (CVD)-Pyrolysis technique using Triazine as a precursor. X-ray diffraction analysis indicates that the as-prepared powder contains a crystalline alpha carbon nitride (α-C3N4) structure with lattice parameters a=6.71 Å, c=4.65 Å and c/a=0.69. The selected area electron diffraction (SAED) pattern, with three diffused circles, confirms the existence of the crystalline α-C3N4 phase . High-resolution TEM images depict carbon nanotubes possessing both even and uneven compartments in the nanotube. X-ray photoelectron spectroscopy confirms the presence of both sp3 and sp2 bonding between carbon and nitrogen atoms for the formation of the α-C3N4 structure. The calculated overall nitrogen content is 17 at. % which is far less than the expected value, but induces compartment formation. The optical bandgap (Eg) of the carbon nitride was evaluated and was found to be 5.5 eV. A mechanism is proposed for the formation of uneven compartment structures in the CNTs. Both even and uneven compartments containing carbon nitride nanotubes (CNNTs) could be ideal for developing hydrogen storage materials.