Transformation of carbon nanotubes to diamond in microwave hydrogen plasma

Multiwall carbon nanotubes (MWCNTs), synthesized by microwave plasma enhanced chemical vapor deposition, were used as the precursor to synthesize diamond in a pure hydrogen microwave discharge. Diamond-scratched silicon wafers, with and without precoated MWCNTs, were placed side by side on a substrate holder. Diamond was formed on both wafers with the consumption of MWCNTs. The present results suggest that the solid–gas–solid transformation mechanism is involved in this process.