Plasmon-Free Surface-Enhanced Raman Spectroscopy Using Metallic 2D Materials.

Area of Science:

• Materials Science
• Nanotechnology
• Analytical Chemistry

Background:

• Plasmon-free surface-enhanced Raman scattering (SERS) using 2D materials is promising for nondestructive analysis.
• Low density of states (DOS) in many 2D materials limits SERS detection sensitivity.
• Metallic 2D transition-metal dichalcogenides (TMDs) are ideal due to abundant DOS, but their synthesis is challenging.

Purpose of the Study:

• To achieve controllable synthesis of ultrathin metallic 2D niobium disulfide (NbS2) for SERS applications.
• To investigate the SERS performance and enhancement mechanism of the synthesized NbS2.
• To demonstrate the practical utility of NbS2-based SERS substrates.

Main Methods:

• Controllable synthesis of ultrathin metallic 2D NbS2 with large domain size.
• Exploration of SERS performance using various concentrations of probe molecules.
• Density functional theory (DFT) calculations to elucidate the enhancement mechanism.

Main Results:

• Successfully synthesized ultrathin metallic 2D NbS2 (<2.5 nm, >160 μm domain size).
• Achieved a remarkable detection limit of 10^-14 mol·L^-1 for SERS.
• DFT analysis revealed a strong correlation between high DOS, binding energy, and SERS enhancement.

Conclusions:

• Metallic 2D NbS2 exhibits superior SERS performance compared to graphene and MoS2 phases due to its abundant DOS.
• The synthesized NbS2 serves as an effective plasmon-free SERS substrate for sensitive detection.
• NbS2-based SERS substrates show potential for practical applications, such as distinguishing red wines.