Carbon nanotube formation on Ni- or Pd-loaded diamond catalysts

A new approach to synthesizing carbon nanotubes (CNTs) on the powdered diamond by catalytic chemical vapor deposition (CVD) was proposed. The catalyst was prepared by impregnating an aqueous solution of Ni(NO 3 ) 2 or an acetone solution of Pd(CH 3 COO) 2 onto surface-oxidized fine powdered diamond (Ni/O-Dia, Pd/O-Dia). CNTs were obtained on the diamond by the decomposition of CH 4 or C 2 H 6 over Ni/ O-Dia or Pd/O-Dia at 400-800 °C. CNTs on Ni/O-Dia from CH 4 showed comparably straight structure to that from C 2 H 6 . CNTs on Pd/O-Dia from C 2 H 6 at 800 °C exhibited uniform, thick (80-130 nm), and morphologically straight structure, which were consisted of a large numbers of thin filamentous carbons.