Surface-Enhanced Raman Scattering on 2D Niobium Carbide (Nb₂CT_X) MXene

MXenes, a new family of 2D metal carbides/nitrides/carbonitrides, have attracted considerable interest in surface-enhanced Raman scattering (SERS), owing to their excellent electronic properties and superhigh hydrophilicity. However, Niobium carbide (Nb₂CT_X) MXene, a second representative of the MXene family, has not been explored much for SERS applications. Herein, we report a successful exfoliation of high-quality and fewlayered Nb₂CT_X nanosheets from its MAX phase (Nb₂AlC) and studied SERS activities using methylene blue, rhodamine 6G, and crystal violet as probe molecules, employing laser excitations of 532, 633, and 785 nm. The results showed that the Raman enhancement of the dye molecules on Nb₂CT_X-based SERS substrate was dependent on the laser-molecule combination, clearly indicating the charge transfer interaction playing a major role in the SERS mechanism. Our findings provide an insight on the development of inexpensive and efficient SERS substrates based on 2D MXenes for molecular detection.