Abstract:

One-dimensional (1D) van der Waals (vdW) materials provide a unique platform for exploring how anisotropic bonding governs crystal growth and enables access to emergent nanoscale morphologies. However, predictive synthetic strategies for controlling their crystallization remain underdeveloped. In this work, we establish chemical design principles for the bottom-up synthesis of 1D vdW nanostructures through the deliberate control of bonding, composition, and defect chemistry. Using modified chemical vapor transport, we demonstrate that strong intra-chain bonding, particularly metal dimerization, promotes catalyst-free growth of ultralong, high-aspect-ratio nanowires in NbS₃-I and MoI₃. Building upon this framework, we show that targeted compositional perturbations through alloying and chalcogen deficiency systematically modify chain flexibility and growth pathways, enabling the formation of complex morphologies including self-coiled nanorings and screw-dislocation-mediated spiral hillocks while preserving the intrinsic anisotropic properties of the parent crystals. Electron microscopy, spectroscopy, diffraction, and first-principles calculations collectively reveal the interplay between bonding anisotropy, lattice perturbations, and crystal growth. Together, these studies establish general synthetic strategies for programming the morphology of 1D vdW materials and provide a foundation for engineering low-dimensional crystals with tailored optical and electronic functionalities.