Liquid Zinc Catalyzed Growth of Single-Walled Carbon Nanotubes with Tailored Chiral Angle Distributions

Understanding the growth mechanisms of single-walled carbon nanotubes (SWCNTs) is essential for achieving controlled synthesis with desired characteristics. To validate the widely discussed screw dislocation theory, we herein design a magnesia-supported zinc (Zn/MgO) catalyst for chemical vapor deposition (CVD) synthesis of carbon nanotubes. Using carbon monoxide as the carbon precursor, high-quality SWCNTs are successfully synthesized at reaction temperatures above 650 °C. Given the low melting point of bulk Zn (419.5 °C), the catalyst nanoparticles are expected to be in liquid state during the CVD process, thereby enabling SWCNT growth via a vapor–liquid–solid mechanism. The catalyst activation is analyzed using d-band center theory, incorporating the influence of the MgO support. Furthermore, the chiral angle distributions of the synthesized SWCNTs, determined by optical characterization, are compared with predictions from the screw dislocation model, and the origins of any discrepancies are discussed. This work not only demonstrates the viability of using liquid catalysts for synthesizing SWCNTs with narrow chirality distributions, but also offers deeper insights into catalyst activation and SWCNT growth mechanisms.