One-Dimensional Pnictogen Allotropes inside Single-Wall Carbon Nanotubes.

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• The discovery of phosphorene has spurred interest in pnictogen nanomaterials like arsenene and antimonene.
• Two-dimensional pnictogens exhibit superior properties to graphene in certain applications.
• Previous work involved filling single-wall carbon nanotubes (SWCNTs) with P4 and As4 molecules.

Purpose of the Study:

• To investigate the synthesis of novel one-dimensional (1D) pnictogen allotropes within SWCNTs.
• To explore the use of vapor-phase red phosphorus for filling SWCNTs.
• To determine the influence of SWCNT diameter on filling efficiency and nanostructure formation.

Main Methods:

• High-resolution electron microscopy was employed to characterize the synthesized nanostructures.
• SWCNTs were filled with red phosphorus from the vapor phase.
• Computational predictions were used to calculate encapsulation energies and band gaps.

Main Results:

• Double-stranded phosphorus zigzag ladders were observed for the first time using vapor-phase filling in larger-diameter SWCNTs.
• Vapor-phase filling of narrow SWCNTs with phosphorus and arsenic showed decreased yields.
• Antimony zigzag ladders were observed, suggesting a common structural motif across pnictogens.
• Computational studies supported experimental findings and predicted metallic behavior for single-stranded zigzag chains.

Conclusions:

• SWCNTs serve as effective nanoscale reactors for creating novel 1D pnictogen allotropes.
• Vapor-phase filling with red phosphorus offers a viable route to specific phosphorus nanostructures.
• The zigzag ladder motif appears to be a prevalent structure across various pnictogens.
• Further exploration of SWCNT diameters >1.5 nm can reveal complex phosphorus nanostructures.