A research team led by Prof. YANG Liangbao from the Hefei Institutes of Physical Science (HFIPS) of the Chinese Academy of Sciences (CAS) has proposed a novel approach based on the near neighbor electron orbit coupling effect. They utilized single atom Au clusters to intercalate 2H-TaS2, achieving surface enhanced Raman scattering (SERS) enhancement effect of two orders of magnitude relative to the parent 2H-TaS2.
The results were published in The Journal of Physical Chemistry Letters.
Two-dimensional (2D) materials have become increasingly popular in the field of analytical chemistry for their potential as metal-free SERS substrates. However, their relatively low enhancement factor compared to precious metals has limited their effectiveness. To address this issue, researchers have been investigating mixed metal nanoparticle 2D material systems or chemically doped 2D materials and their corresponding SERS enhancement mechanisms.
In their study, the research team focused on a simplified model of bilayer 2H-TaS2 with the insertion of single-atom-layer Au clusters. X-ray photoelectron spectroscopy (XPS) results showed that the interlayer Au affected the surface charge of the neighboring 2H-TaS2.
In addition, micro area UV/vis-NIR diffuse reflectance spectra indicated a shift in the absorption peak of Au-2H-TaS2 to 570 nm, confirming an increase in electron density on the surface of 2H-TaS2.
Combining experimental results with first-principles calculations, the team revealed that the d-orbital electrons on the Au surface were coupled with neighboring 2H-TaS2, leading to an increase in local electron density and creating a strong local electromagnetic field.
This study provides important insights into the enhancement mechanisms of SERS using nonprecious metal compounds and can guide the development of new SERS substrates, according to the team.
This Figure Revealing the SERS Enhancement Principle of Au-2H-TaS2 Based on the Coupling Effect of Nearest-Neighbor Electron Orbits (Image by WEN Shirui)