In recent years, precious-metal catalysts, such as silver (Ag)[15],
gold (Au)[16], titanium (Ti) and palladium (Pd) [17], have also been
used for growing CNCs. Chiu and coworkers used liquid-phase
metallic K with Ag or Au as the catalyst to grow amorphous CNCs
from acetylene on Si substrates; they proposed a vapor-liquidsolid-growth mechanism for explaining the CNC growth [15,16].Nitze et al. used C60-supported Pd-catalyst particles at 550 C to grow HCNFs[17]. Using Pd nanoparticles, they could grow homogeneous CNCs with a highly periodic pitch and diameter.