Quasi-Metal for Highly Sensitive and Stable Surface-Enhanced Raman Scattering

Area of Science:

• Materials Science
• Nanotechnology
• Spectroscopy

Background:

• Surface-enhanced Raman scattering (SERS) typically relies on noble metals.
• Existing SERS substrates face challenges with sensitivity and stability, particularly those utilizing the chemical mechanism (CM).
• Noble-metal substrates often depend on the surface plasmon resonance (SPR)-induced electromagnetic mechanism (EM).

Purpose of the Study:

• To investigate quasi-metallic vanadium dioxide (VO2) nanosheet arrays as a novel SERS substrate.
• To evaluate the sensitivity and stability of VO2 nanosheets for SERS applications.
• To elucidate the mechanisms contributing to the SERS activity of VO2 nanosheets.

Main Methods:

• Fabrication of quasi-metallic VO2 nanosheet arrays.
• Experimental characterization of SERS performance using analytes.
• Theoretical calculations to understand charge transfer and SPR effects.
• Determination of the lowest detectable limit and Raman enhancement factor (EF).

Main Results:

• VO2 nanosheet arrays demonstrated high sensitivity with a lowest detectable limit of 10⁻¹⁰ M.
• A maximum Raman enhancement factor (EF) of 6.7 × 10⁷ was achieved, comparable to noble metals.
• Experimental and theoretical data confirmed strong interfacial charge transfer and SPR effects.

Conclusions:

• Quasi-metallic VO2 nanosheets represent a highly sensitive and stable SERS substrate.
• The SERS performance is attributed to a combination of charge transfer and SPR effects.
• Quasi-metals are promising for SERS detection, with CM contributing significantly to their activity.