Efficient Growth of 1D Van der Waals Heterostructures on Zeolite-Supported SWCNTs.

The controlled synthesis of 1D van der Waals (1D vdW) heterostructures, specifically single-walled carbon nanotubes encapsulated within boron nitride nanotubes (SWCNT@BNNT), presents a challenge due to an incomplete understanding of the factors influencing BNNT growth. This study investigates the growth yield of SWCNT@BNNT heterostructures produced using zeolite-supported SWCNT templates on SiO-coated Transmission Electron Microscopy (TEM) grids, which enable in situ synthesis and thorough evaluation of each step without compromising the nanotube structure. The high-resolution TEM analysis reveals a significant improvement in BNNT coverage on individual nanotubes, increasing from 9% to 42%, through optimization of the ammonia borane precursor amount. A thorough comparison of BNNT growth efficiency is performed using zeolite-supported SWCNT templates against the current benchmark of free-standing SWCNT films, highlighting comparable synthesis yields despite different morphologies and SWCNT diameter distributions. By integrating all Raman and TEM data from the studied SWCNT@BNNT samples, a correlation between BNNT coverage and the intensity of the buckling R-mode of BNNTs is established, providing a reliable criterion for evaluating BNNT growth efficiency in 1D vdW heterostructures. This work advances the understanding and characterization of 1D vdW heterostructures, offering insights into synthesizing hetero-nanotubes using other types of SWCNT templates and paving the way for their diverse applications.