Synthesis and characterization of nitrogen-doped carbon nanotubes

In this work, nitrogen-doped carbon nanotubes (N-CNTs) were prepared by a facile chemical vapor deposition method using Fe/SBA-15 molecular sieve as the catalyst and different organic amines as carbon source and nitrogen source. The morphology, structure and composition of the obtained samples were characterized by a series of analytical techniques. The results revealed that the as-obtained N-CNTs are hollow bamboo-like nanofibers with a diameter of 30–50 nm and have a smooth surface. The effects of different organic amines on the yield, composition, morphology and properties of the N-CNTs were investigated. The N-CNTs prepared from diethylamine (DEA) have the highest yield (2.2 g (g cat)−1). The water absorption of the as-synthesized N-CNTs samples increases with the increase in the molar ratio of N/C. The N-CNTs prepared from ethylenediamine (EDA) have the highest N/C molar ratio (0.35) and the highest water absorption (224.4 mg g−1). The thermal conductivity (TC) of the silicon-based composites increases with the increase of N-CNTs. However, the N/C molar ratio of N-CNTs has a negative effect on the TC of silicon-based composites.