Metallic NbS2 one-dimensional van der Waals heterostructures

TL;DR

This paper reports the successful synthesis and characterization of metallic NbS2 one-dimensional van der Waals heterostructures using a modified chemical vapor deposition method, revealing their structural, optical, and stability properties.

Contribution

It introduces a novel remote salt-assisted CVD approach for controlled growth of high-quality NbS2 nanotubes with detailed structural and optical analysis.

Findings

Crystalline NbS2 nanotubes confirmed by TEM and STEM

Metallic nature demonstrated by UV-vis-NIR and FTIR spectroscopy

Bi-layer preference and oxidation behavior characterized

Abstract

This study presents the experimental realization of metallic NbS2-based one-dimensional van der Waals heterostructures applying a modified NaCl-assisted chemical vapor deposition approach. By employing a "remote salt" strategy, precise control over NaCl supply was achieved, enabling the growth of high-quality coaxial NbS2 nanotubes on single-walled carbon nanotube-boron nitride nanotube (SWCNT-BNNT) templates. With the remote salt strategy, the morphologies of as synthesized NbS2 could be controlled from 1D nanotubes to suspended 2D flakes. Structural characterization via high-resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy (STEM) confirms the formation of crystalline NbS2 nanotubes, revealing a distinct bi-layer preference compared to monolayer-dominated semiconducting transition metal dichalcogenide analogs. Optical analyses using UV-vis-NIR and FTIR spectroscopy highlight the metallic nature of NbS2. With Raman analysis, oxidation studies demonstrate relative higher degradation rate of 1D NbS2 under ambient conditions. Density functional theory (DFT) calculations further elucidate the stabilization mechanism of bi-layer NbS2 nanotubes, emphasizing interlayer charge transfer and Coulomb interactions. This work establishes a robust framework for synthesizing metallic 1D vdW heterostructures, advancing their potential applications in optoelectronics and nanodevices.