Surfactant-Assisted Isolation of Small-Diameter Boron-Nitride Nanotubes for Molding One-Dimensional van der Waals Heterostructures

Rolling two-dimensional (2D) materials into 1D nanotubes allows for greater functionality. Boron-nitride nanotubes (BNNTs) can serve as insulating 1D templates for the coaxial growth of guest nanotubes, without interfering with property characterization. However, their application as 1D templates has been greatly hindered by their poor dispersibility, inevitably resulting in the formation of thick bundles. Here we present the facile preparation of well-dispersed BNNT templates via surfactant dispersions and synthesis of 1D van der Waals heterostructures based on the BNNTs. Comprehensive microscopic analyses show the isolation of clean, high quality BNNTs. Statistical analyses revealed that small-diameter double-walled BNNTs are highly enriched by chemical peeling of BN sidewalls through the sonication process. We further demonstrate that the isolated BNNTs can template the coaxial growth of carbon and MoS2 nanotubes by using chemical vapor deposition. The present strategy can be applied to the synthesis of a variety of nanotubes, thereby allowing for their characterization.