Advances in the synthesis and scalable manufacturing of single-walled carbon nanotubes (SWCNTs) remain critical to realizing many important commercial applications. Here we review recent breakthroughs in the synthesis of SWCNTs and highlight key ongoing research areas and challenges. A few key applications that capitalize on the properties of SWCNTs are also reviewed with respect to the recent synthesis breakthroughs and ways in which synthesis science can enable advances in these applications. While the primary focus of this review is on the science framework of SWCNT growth, we draw connections to mechanisms underlying the synthesis of other 1D and 2D materials such as boron nitride nanotubes and graphene.

Growing coaxial nanotubes: Heterostructures of highly crystalline two-dimensional materials such as graphene, hexagonal boron nitride (hBN), and molybdenum disulfide (MoS ₂ ) are now routinely assembled from films or grown as layers. Xiang et al. report the growth of one-dimensional analogs of these heterostructures on single-walled carbon nanotubes (SWCNTs) through a chemical vapor deposition (see the Perspective by Gogotsi and Yakobson). Single-crystalline monolayers or multilayers of hBN or MoS ₂ were grown that maintained the electrical conductivity of the SWCNT. A monolayer of MoS ₂ was grown on a trilayer of hBN that encapsulated a SWCNT. Science , this issue p. 537 ; see also p. 506