Effect of precursors on the growth of carbon filaments onto clay surface

摘要

The successful growth of carbon filaments on two different precursors. i.e., the pristine sodium-montmorillonite (Na~+MMT), which undergoes reflux at 100℃ (r-MMT). and the Na~+MMT exchanged with Fe~(3+) ions (MMT(Fe)), was attained through chemical vapor deposition (CVD). The products obtained were characterized by X-ray diffraction, thermogravimetry, scanning electron microscopy, and transmission electron microscopy. Refluxing can make the Fe~(3+) ions in the octahedral layer of Na~+MMT migrate to the interlayer and exchange with Na~+ ions. Furthermore, through calcination at 500 ℃, the Fe~(3+) ions migrate again to the surface of the clay layer and form iron oxides, which can serve as precursors for the deposition of carbon. Although r-MMT contained less iron than the MMT(Fe), the ultimate yield of carbon components grown was almost the same, indicating that the iron species in r-MMT possess higher catalytic activity. However, on the surface of r-MMT, CVD hardly generated carbon nanotubes with a clear hollow structure but that those with a carbon fiber structure instead.