Nanowire-Activated Formation of Coaxial Core-Shell Nanostructure Encapsulated by Carbon Nanotube.

Molecular dynamics simulations have unveiled the atomic-scale mechanisms underlying the formation of core-shell nanostructures involving nanowires (NWs) and graphene. Our study identifies two pivotal steps in this process: the self-scrolling of graphene around NWs and the subsequent edge connection to form carbon nanotubes (CNTs). The tendency of graphene to scroll is governed by the complex interplay of van der Waals forces. Stronger interactions between the NW and graphene act as a driving force, significantly promoting the scrolling process. We find that the initial velocity of NWs significantly influences CNT formation, with optimal velocities enabling the creation of defect-free CNTs. Increasing NW velocity enhances the graphene self-scrolling and wrapping dynamics. NW diameter plays a critical role; larger diameters minimize bending deformation, favoring defect-free CNT formation, but also augment transverse wave amplitudes, increasing relative sliding resistance between graphene and NWs and decelerating van der Waals interactions, thereby reducing scrolling speed. We determine that graphene length must meet the condition L = π(+2r) and the width-to-length ratio (W/L) must surpass a threshold for effective NW/CNT core-shell structure formation. Multilayer graphene, experiencing reduced van der Waals adsorption from the substrate, is more prone to self-scrolling. Lower temperatures enhance graphene wrapping around NWs, facilitating edge connection and system stabilization, whereas higher temperatures disrupt core-shell integrity by increasing atomic thermal motion, preventing edge connection. These findings establish a solid theoretical foundation for the design and fabrication of advanced NW/CNT core-shell nanostructures.