New developments in the growth of 4 Angstrom carbon nanotubes in linear channels of zeolite template

Abstract

We report new developments on the chemical vapor deposition growth of 0.4nm single-walled carbon nanotubes (SWCNTs) inside the linear channels of the aluminophosphate zeolite, AlPO4-5 (AFI), single crystals (0.4nm-SWCNT@AFI). Ethylene (C2H4) and carbon monoxide (CO) were used as the feedstock. Polarized Raman spectroscopy was used to analyze the structure and quality of SWCNTs, both the radial breathing mode and G-band are much clearer and stronger than the samples grown by the old process which used template tripropylamine molecules for growing SWCNT@AFI. From the Raman spectra, it is clearly seen that the RBM is composed of two peaks at 535 and 551cm−1. By using the pseudopotential module in Material Studio to calculate the Raman lines, the 535cm−1 peak is attributed to the (5,0) SWCNTs and the 551cm−1 peak to the (3,3) SWCNTs. The abundance of (4,2) is relatively small. Thermal gravity analysis showed that while the samples grown by CO display less than 1wt% of carbon, for the samples heated in C2H4 atmosphere the weight percentage of SWCNTs is around 10%, which implies ∼30% of the AFI channels are occupied with SWCNTs, a significant increase compared with the previous samples.