Ti₃C₂TMXene as surface-enhanced Raman scattering substrate

Area of Science:

• Materials Science and Nanotechnology
• Spectroscopy and Photonics

Background:

• Surface-Enhanced Raman Scattering (SERS) relies on electromagnetic field enhancement for sensitive molecular detection.
• Ti3C2Tx MXene flakes are explored as potential substrates for SERS applications due to their unique properties.

Purpose of the Study:

• To theoretically analyze electromagnetic field enhancement mechanisms for SERS using Ti3C2Tx MXene flakes.
• To investigate the influence of MXene flake characteristics on SERS enhancement factors (EF).

Main Methods:

• Utilized COMSOL simulations to model SERS enhancement factors (EF) for R6G molecules near MXene flakes.
• Modeled the dye molecule as a sphere with an experimentally derived polarizability spectrum.
• Analyzed the role of quadrupole surface plasmon (QSP) oscillations and interband transitions (IBTs).

Main Results:

• Demonstrated that quadrupole surface plasmon (QSP) oscillations are the primary mechanism for SERS enhancement in the 500-1000 nm range.
• Showed that interband transitions (IBTs) strengthen QSP resonances, yielding EF values of 10^5-10^7.
• Found weak sensitivity of EF to MXene nanoparticle shape and size, attributed to QSP and IBT independence from flake geometry.

Conclusions:

• MXene substrates exhibit geometry-independent SERS enhancement, simplifying substrate synthesis for universal applications.
• The 'lightning rod' and 'hot-spot' effects contribute to electromagnetic SERS enhancement.
• Ti3C2Tx MXene flakes are promising for the facile fabrication of versatile SERS substrates.