Surface-Enhanced Raman Spectroscopy of Two-Dimensional Tin Diselenide Nanoplates

Surface-enhanced Raman spectroscopy (SERS) is a powerful spectroscopy technique to detect and characterize molecules at a very low concentration level. The two-dimensional (2D) semi-conductor layered material, tin diselenide (SnSe2), is used as a new substrate for enhancing the Raman signals of adsorbed molecules. Three kinds of molecules—Rhodamine 6G (R6G), crystal violet (CV), and methylene blue (MB)—are used as probe molecules to evaluate the SERS performance of SnSe2. The Raman signals of different molecules can be enhanced by SnSe2 nanoplates (NPs). The distinguishable Raman signal of R6G molecules can be obtained for adsorbent concentrations as low as 10−17 mol/L. Based on a detailed analysis of the bandgap structure and opto-electrical properties of SnSe2 NPs, we discuss the process of charge transfer and the Raman enhancement mechanism of SnSe2 NP. The high Raman sensitivity of SnSe2 NPs is related to the charge transfer between molecules and SnSe2, 2D layered structure, and indirect bandgap of few-layered SnSe2. The research results will help to expand the application of SnSe2 in microanalysis, improve the measurement accuracy of SERS, and possibly find use in optoelectronic device integration.