Nitrogen-doped single-wall carbon nanotubes(SWCNTs) with diameters in the range of 1.1–1.6 nm were synthesized on a large scale by floating catalyst chemical vapor deposition. Ferrocene, methane and melamine were respectively used as the catalyst precursor, carbon source and nitrogen source. The content of nitrogen introduced into the SWCNT lattice was characterized to be ~0.4 at.%. This resulted in a decreased mean diameter, narrower tube diameter distribution, and increased surface area of the SWCNTs. The temperatures at which the rate of weight loss reaches the maximum value for N-SWCNTs are ~785°C, similar to that of pure SWCNTs, indicative of their high-quality and good crystallinity. These N-SWCNTs exhibited a metallic behavior and desirable electrochemical oxygen reduction reaction activity.
One of the most unique structural characteristics of carbon nanotubes(CNTs) differentiating from other carbon materials is their hollow nanochannles,which can be utilized for encapsulating and loading foreign matters.The anodic aluminum oxide(AAO) template technique enables the diameter,length,and cap structure control of the replicated CNTs,and thus shows advantages in pore structure control over the traditional CNT growth approaches.This review details the synthesis of CNTs with tunable diameter,length,wall thickness,and crystalline by using the AAO template method.The doping of heteroatoms and filling of foreign matters into AAO-CNTs are also addressed.Moreover,the main challenges and developing trends of the AAO template method are discussed.
