Synthesis, Photoluminescence, and Magnetic Properties of Nitrogen-Doping Helical Carbon Nanotubes

Over Ni nanoparticles generated by means of a combined sol–gel/reduction method, helical carbon nanotubes (HCNTs) were synthesized in acetylene pyrolysis at 425 °C. By annealing the pristine HCNTs in NH3 atmosphere, the N-doped HCNTs were obtained. The dependence of annealing temperature on the nitrogen content and doping type of the N-doped HCNTs was studied. The photoluminescence (PL) properties of the pristine HCNTs and N-doped HCNTs were examined systematically at room temperature (RT). The results demonstrated that the pristine HCNTs exhibit strong ultraviolet (UV) PL at 368 nm. By doping the pyridinic and graphitic N into the pristine HCNTs, the UV PL could be enhanced. Moreover, the magnetic properties of the pristine and N-doped HCNTs have been measured.