Synthesis of close-packed multi-walled carbon nanotube bundles using Mo as catalyst

A simple mixture of porous magnesium oxide and commercial molybdenum oxide shows high efficiency for the synthesis of carbon nanotubes through the catalytic decomposition of methane at 900 °C. Field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and transmission electron microscopy (TEM) were used to characterize the products. The results indicate that close-packed multi-walled carbon nanotube (MWCNT) bundles were synthesized and the carbon nanotubes restricted within the bundles were about 5–7 nm in diameter. A growth mechanism for the bundles was suggested based on the FE-SEM images of bundles produced using different reaction times, and the X-ray diffractions of the raw products grown at the initial stage. Raman spectroscopy and FE-SEM results on the bundles grown using different methane flow rates confirmed the growth mechanism of close-packed MWCNT bundles.