The SERS activity of NC-NbSe₂ film. (A) Schematic diagram of the NC-NbSe₂ films used for SERS activity towards R6G molecules. (B) Raman spectra of R6G coated on SiO₂/Si, C-NbSe₂ films, NC-1-NbSe₂ film, and NC-NbSe₂ film, respectively, correspond to 10 μL R6G solution (10⁻⁶ M) on substrates. Notably, the Raman intensities are normalized to the integration times. (C) The comparison of characteristic vibrational Raman peaks of R6G on NC-NbSe₂ and C-NbSe₂ film. Notably, the overall intensity was normalized to the intensity of peak at 1361 cm⁻¹ on C-NbSe₂ film. (D) The ADF-STEM images of NC-NbSe₂ film. Notably, the amorphous domain (highlighted in purple) implies the GBs-enhanced surface adsorption of organic species on NC-NbSe₂ film. (E) The corresponding SAED pattern of the bottom two domains in NC-NbSe₂ film. (F) Diagram of energy level diagram and charge transfer transitions between R6G and NbSe₂ film. Notably, μ_i-CT and μ_k-CT denote the charge transfers from the HOMO of the R6G molecules to the Fermi level of NbSe₂, and from the Fermi level of NbSe₂ to the LUMO of the R6G molecules, respectively. The DOS near the Fermi level is based on the results of previous studies [54,55].