(454e) Single-Walled Carbon Nanotube Chirality Correlation to the Nanocatalyst Structure

Single-walled carbon nanotubes (SWCNTs) possess a variety of mechanical, electronic, and optical properties making them attractive for a myriad of technological applications. Nevertheless, the realization of such applications is hindered by the lack of control of the SWCNT chirality. The chirality is related to the helicity of the nanotube wall lattice and determines the nanotube properties. Controlling the chirality is a very complex problem due to the number of process parameters involved. During chemical vapor deposition (CVD) growth, metallic catalyst nanoparticles are used to catalytically decompose a carbon-containing gas, and promote the SWCNT nucleation and growth. Using molecular simulations, we study a possible correlation between the catalyst architecture and the structure of the growing carbon nanotubes. We use density functional theory to investigate the existence of a correlation between the nanoparticle structure and chiral nanotube caps, and the formation of chirality-related carbon structures on stepped and chiral surfaces. The surfaces are intended to model the formation of steps observed in the nanoparticle during SWCNT nucleation experiments. The results suggest that certain features in specific nanocatalyst structures would tend to favor near-armchair nanotubes over near-zigzag nanotubes and viceversa, encouraging further study in the control of the catalyst structure.