Surface-enhanced Raman scattering on two-dimensional Nb2CTX MXene

MXenes have garnered significant attention for surface-enhanced Raman scattering (SERS) applications due to their exceptional electronic properties and remarkable hydrophilicity. However, niobium carbide (Nb2CTX), a notable member of the MXene family, has been underexplored for SERS applications. In this work, we present a comprehensive investigation of the SERS properties of Nb2CTx nanosheets, using methylene blue (MB) and crystal violet (CV) as probe molecules under laser excitations at 532 and 488 nm. The results revealed that the Raman enhancement of dye molecules on the Nb2CTx-based SERS substrate was determined by the interplay between laser energy and the probe molecule. The two orders of magnitude higher enhancement factor (EF) for MB (2.12 × 106) compared to CV (2.65 × 104) obtained using 532 nm laser excitation was attributed to a light-induced resonance charge transfer transition within the MB-Nb2CTX system. The distinctly different EF values for MB and CV suggest that SERS technology based on chemical mechanisms could enable selective molecular detection. Our results provide valuable insights into the SERS mechanism and contribute to the development of cost-effective and 2D MXene-based selective SERS substrates for molecular sensing applications.