Synthesis, Characterization and Chirality Identification of Double‐Walled Carbon Nanotubes Available to Purchase

Catalytic decomposition of methane with the addition of sulfur was used to synthesize double‐walled carbon nanotubes (DWNTs) and their aligned long ropes. High‐resolution transmission electron microscopy (HRTEM) and laser Raman resonance spectroscopy were employed to study the structure and diameter distribution of the as‐prepared DWNTs. HRTEM observations show that the outer and inner diameter of the DWNTs are in the range of 1.6–3.6 and 0.8–2.8 nm, respectively. Moreover, we found that the interlayer spacing of DWNTs is not a constant, ranging from 0.34 to 0.41 nm. The DWNTs show corresponding peaks in the radial breathing mode (RBM) from resonant Raman spectra, which are considered to be associated with the inner tubes as well as outer tubes of DWNTs. Moreover, we can also distinguish metallic and semiconducting nanotubes based on the resonantly enhanced RBM features of the DWNTs, which provides a basis for their applications in electronic field.