Enhanced Raman scattering on two-dimensional palladium diselenide

Area of Science:

• Materials Science
• Nanotechnology
• Spectroscopy

Background:

• Two-dimensional (2D) semiconductors offer unique properties for Surface-Enhanced Raman Scattering (SERS) applications.
• Graphene and transition metal dichalcogenides (TMDs) are established Raman enhancers.
• Exploring novel 2D materials is crucial for advancing SERS-based molecule sensing.

Purpose of the Study:

• To investigate atomically-thin palladium diselenide (PdSe2) as a novel SERS substrate.
• To evaluate the SERS performance of PdSe2 for detecting various molecules.
• To understand the mechanism behind the observed Raman enhancement.

Main Methods:

• Fabrication and characterization of few-layer and monolayer PdSe2.
• SERS measurements using rhodamine 6G (R6G), crystal violet (CV), and rhodamine B (RhB) as probe molecules.
• Analysis of Raman spectra to determine detection limits and enhancement factors.
• Investigation of the effect of an Al2O3 interlayer on SERS performance.
• Exploration of thickness-dependent properties, anisotropy, and air stability.

Main Results:

• Stable and significant Raman enhancement was observed for R6G, CV, and RhB on PdSe2.
• A low detection limit of 10^-9 M and an enhancement factor of 10^5 for R6G on monolayer PdSe2 were achieved.
• Raman spectra confirmed a predominant charge transfer mechanism contributing to the enhancement, especially with an Al2O3 layer.
• PdSe2 exhibited strong thickness-dependent SERS properties, in-plane anisotropy, and excellent air stability.

Conclusions:

• Atomically-thin PdSe2 is a highly effective SERS substrate for molecule detection.
• The material demonstrates excellent sensitivity and stability, suitable for practical sensing applications.
• This study provides valuable insights into the chemical mechanism of SERS enhancement in 2D materials.