"Missing" One-Dimensional Red-Phosphorus Chains Encapsulated within Single-Walled Carbon Nanotubes.

Area of Science:

• Materials Science
• Nanotechnology
• Solid-State Chemistry

Background:

• Single-walled carbon nanotubes (SWCNTs) are explored as nanoscale reaction vessels.
• Understanding the behavior of elements confined within nanotubes is crucial for novel material synthesis.

Purpose of the Study:

• To identify and characterize the "missing" 1D-phosphorus allotrope.
• To investigate phosphorus condensation within intermediate diameter SWCNTs (1.6-2.9 nm).

Main Methods:

• Experimental techniques: Thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), High-resolution transmission electron microscopy (HRTEM), Energy dispersive X-ray spectroscopy (EDS).
• Theoretical methods: Density functional theory (DFT) simulations.
• Spectroscopic analysis: Low-frequency Raman spectroscopy.

Main Results:

• Identification of linear P8]P2 and cross-linked double-chains of red phosphorus inside SWCNTs.
• Elemental phosphorus content estimated at ~7 atom % within the SWCNTs.
• HRTEM and DFT simulations confirmed the chain structures and packing density.
• A unique spectroscopic signature for phosphorus chain cross-linking was identified.

Conclusions:

• The study successfully identified confined 1D-phosphorus allotropes within SWCNTs.
• Results provide a comprehensive understanding of phosphorus behavior and structure dependence on nanotube diameter.
• This work opens new avenues for exploring confined elemental forms and their properties.