Fabrication of silica nanotubes using silica coated multi-walled carbon nanotubes as the template.

Silica nanotubes were synthesized using the multi-walled carbon nanotubes (MWCNTs) as the template material. First, we prepared silica coated MWCNT composites by surface oxidation of MWCNTs using KMnO(4) in the presence of a phase transfer catalyst and followed by grafting of 2-aminoethyl 3-aminopropyl trimethoxy silane, AEAPS. The amine groups in grafted AEAPS on MWCNTs could activate the silica shell formation by acid-base interaction. The synthesized silica was formed a uniform layer on MWCNTs with a controllable thickness and possessed sturdy 3-dimensional stability. After calcinations at 800 degrees C, the inner MWCNTs of the composite were completely decomposed and the outer silica shell layer maintained without distortion of its original shape. Finally, we could obtain the silica nanotubes having 13.0 nm of average layer thickness.