Origin of layer-dependent SERS tunability in 2D transition metal dichalcogenides

Two-dimensional (2D) semiconductors are expected to replace noble metals to become the matrix materials of the next generation of commercial surface-enhanced Raman scattering (SERS) chips. Herein, we systematically studied the influence of the interlayer interaction on the SERS activity of 2D semiconductors from a brand-new perspective and comprehensively analyzed the physicochemical process of 2D semiconductor interlayer modulated SERS. Taking transition metal dichalcogenides as examples, we chose PtSe₂ with strong interlayer interactions and ReS₂ with weak interlayer interactions to analyze the physicochemical process of 2D semiconductor interlayer modulated SERS by first-principles calculations. PtSe₂ and ReS₂ samples with various thicknesses were prepared respectively, and the results of comparative experiments proved that the layer-dependent SERS tunability of 2D semiconductors is directly related to the interlayer interaction. This work provided a novel method for further improving the SERS detection limit of 2D semiconductors and a possible strategy for the industrial upgrading of commercial SERS chips.