Au–Pd catalyzed growth of carbon nanofibers mat

Carbon nanofibers (CNFs) mat was synthesized from Au–Pd catalyst at 700 °C for 60 min in 10 kPa of the gas mixture of C2H2, H2 and Ar by thermal chemical vapor deposition (CVD). Fine Au–Pd catalyst as admixture on the growth substrate of SiO2 was adopted for the growth of CNFs mat. Fine Pd particles without Au particles were detected at the top/inside of as-grown CNFs by TEM-EDS analysis. The Au component within Au–Pd particles with ca. 1.5 nm did not contribute to the CNF growth. On the other hand, the growth scale of individual CNF was ranged from 5 to 150 nm in diameter and less than 100 μm in length, by controlling H2 or Ar concentration in carbon source gas of C2H2/Ar or C2H2/H2/Ar. It seemed that Ar gas accelerated the growth of the CNFs mat and the length of each CNF was increased with increasing the supplying amount of H2. In contrast, H2 induced the lower growth density of CNFs mat and the decrease in the diameter of those. The CNFs mainly grow through adsorption and decomposition of acetylene on the surface of Au–Pd catalyst and precipitation of carbon on the surface of those.