High yield synthesis of helical carbon nanotubes catalyzed by porous precursor with terrace morphology

• Helical carbon nanotubes with high yield and purity were synthesized via chemical vapor deposition.
• Superfine and uniformly dispersed catalyst precursors were obtained.
• Relationship between structures and efficacy differences of catalyst precursor was revealed.

Superfine and uniformly dispersed catalyst precursor was obtained through a novel precipitation/sol–gel/reduction technique, which had multi-scale multi-layered porous structures with large surface areas. Helical carbon nanotubes (HCNTs) with good purity were then synthesized through chemical vapor deposition (CVD) by acetylene decomposition over the as-obtained precursor. The yield of the HCNTs was nearly three times of the highest value ever reported. The high yield and good quality of the HCNTs was attributed to the peculiar structures of the precursor that could decompose into catalyst with large surface area and high activity. Furthermore, the structures and catalytic efficiencies of the catalyst precursors prepared through other two different approaches were also investigated to reveal the relationship between the structures of the precursor and their capability differences in catalyzing the HCNTs growth.