Drastic increase in catalyst productivity of nanoclay-supported CVD-grown carbon nanotubes by organo-modification

The organo-modification of montmorillonite (Mt) prior to catalyst insertion was proposed as a promising approach to increase carbon nanotube (CNT) yield on nanoclay (NC) supports in catalytic chemical deposition (CVD) reaction. The behavior of organo-modified montmorillonite (OMt) as the support in CVD reaction was compared with that of Mt. According to morphological images and Raman spectra, the carbon atoms form CNT in case of both Fe-loaded pristine Mt and OMt. Decreasing gas flow-rate and diminishing hydrogen fraction in growth atmosphere were found to favor improvement of CNT yield, whereas generally tended to deteriorate its quality. TGA results showed that the CNT content of OMt-supported hybrids were drastically increased compared to that of non-modified Mt. There was about two- to fifteen-fold increase in CNT yield depending on the CVD conditions. This observation was found correlated to the larger specific surface area (SSA) and d001-value of Fe-loaded OC. The evident advantages of OMt as catalyst support include efficient and scalable synthesis of high thermally stable NC/CNT hybrid at low cost.