Large-scale synthesis of amorphous phosphorus nitride imide nanotubes with high luminescent properties

A facile solvothermal approach was successfully developed for the large-scale synthesis of amorphous phosphorus nitride imide (H_3xP₃N_5+x) nanotubes with high luminescent properties by the reaction of 1,3,5-hexachlorotriphosphazene (P₃N₃Cl₆) with sodium amide (NaNH₂) at low temperatures. Transmission electron microscope images showed that the inner diameter of nanotubes is 120 ± 20 nm, wall thickness is 40 ± 10 nm, and length ranges from several to ten micrometers. Scanning electron microscope images revealed that the proportion of the nanotubes exceeds 90%. X-ray photoelectron spectroscopy spectra indicated that the binding energies of P2p and N1s are 133.30 and 398.40 eV, respectively, and the atomic ratio of P:N is 3:5.13. The infrared spectra of the sample are comparable to those of the reported HPN₂ and HP₄N₇. Thermogravimetric analysis revealed that the product is very robust in a nonoxidizing atmosphere. The structure and the optical properties of the product and the annealed samples were investigated by x-ray diffraction and photoluminescence measurements, respectively.