Large scale N-doped GNTs@a-SiO x(x=1–2) NPs: template-free one-step synthesis, and field emission and photoluminescence properties

N-doped graphene nanotubes coated by amorphous SiO x(x=1–2) nanoparticles (N-doped GNTs@a-SiO x(x=1–2) NPs) were synthesized by a simple template-free one-step calcination method. The method not only possesses a simple synthesis process, but also protects the graphene nanotubes from damage caused by template removal. The characterization results show that amorphous SiO x(x=1–2) nanoparticles with a size of 20–40 nm were located on the surface of the N-doped graphene nanotubes. The product synthesized under the optimal molar ratio of raw materials (C 3 H 6 N 6 : Si/SiO 2 powders = 1 : 2) presents a lower turn-on electric field of 0.663 V μm −1 , and especially, a very low threshold electric field of 1.575 V μm −1 (at 10 mA cm −2 current density). Moreover, it also showed improved intensity of yellow-green emission compared with N-doped GNTs. The reason for the outstanding performance of N-doped GNTs@a-SiO x(x=1–2) NPs was attributed to the synergistic effect of N-doping, a large number of oxygen vacancy defects of SiO x(x=1–2) , and the unique morphology. The research results not only provide a new method for large-scale synthesis of N-doped GNTs@a-SiO x(x=1–2) NPs nanocomposites with excellent field emission properties and photoluminescence properties, but also lay the foundation for their applications in various fields.