Enhanced ferromagnetic properties of N₂ plasma-treated carbon nanotubes

A nitrogen plasma treatment protocol has been applied to carbon nanotubes as a way to modulate their magnetic properties by the microwave plasma chemical vapor deposition method. The nitrogen treatment is a simple and effective strategy to fundamentally affect the magnetic performance of CNTs, which is related to the microwave power and the time of the treatment. The best treatment time is 30 min with the microwave power of 120 W corresponding to the N content (defined N/C atomic ratio in at.%) which is 2.15 at.% and the biggest value of Ms is 0.5227 emu/g. Using Raman, XPS and EDS mapping, it is proved that N exists in CNTs and the pyridine N and amine N bonding configurations contribute to ferromagnetic origin. Our study of N₂ plasma treatment doping into CNTs to enhance ferromagnetic properties provides an effective technique for the N doping and massive synthesis of ferromagnetic graphene.