Selective Surface-Enhanced Raman Scattering-based Sensing 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 (MB), rhodamine 6G (R6G), and crystal violet (CV) as probe molecules, employing the laser excitation of 532 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, giving the highest enhancement for CV and lowest for MB at 10^-4 M concentration. Moreover, only CV was detected from the mixture of all three dyes at a lower concentration 10^-5 M, indicating a possibility of selective SERS sensing on novel 2D materials like Nb₂CT_X. The results clearly infer that the charge transfer interaction plays a major role in the SERS mechanism. Our findings provide an insight on the development of inexpensive, and selective SERS substrates based on 2D MXenes for molecular detection.

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