Synthesis of mesoporous molecular sieves as catalytic template for the growth of single walled carbon nanotubes

Mesoporous Mo MCM-41 and Nb MCM-41 molecular sieves were synthesized in various ratios by hydrothermal method and were characterized by XRD, N2 adsorption isotherm and DRS-UV spectroscopy. The calcined samples were used as catalysts for the growth of carbon nanotubes using acetylene by chemical vapor deposition technique at 700–900 °C. The deposited carbon materials by acetylene decomposition, were found to be more in the case of Nb MCM-41 than in Mo MCM-41, and their catalytic activity was found to be in the order as Si/Nb = 100 > 75 > 50 > 25, and the same trend is followed for Mo MCM-41 molecular sieves. The catalytically synthesised carbon materials were characterized with Raman spectroscopy, SEM and TEM. We have obtained single walled carbon nanotubes in bundles with a tube diameter of 1.06–2.9 nm and 1.08–2.3 nm formed over Mo MCM-41 and Nb MCM-41, respectively, according to Raman spectra. Similarly well graphitised single walled carbon nanotubes formation was observed from TEM. From this observation, it is confirmed that Mo MCM-41 (100) and Nb MCM-41 (100) exist as stable catalysts for the synthesis of single walled nanotube.