Controllable MXene nano-sheet/Au nanostructure architectures for the ultra-sensitive molecule Raman detection

Surface-enhanced Raman scattering (SERS) spectroscopy aims to augment the relatively weak molecular vibrations based on electromagnetic enhancement (EE) and chemical enhancement (CE) mechanisms, and offers a potential way for material identification, even up to the single-molecule level, under atmospheric conditions. We have subtly combined the advantages of EE and CE, and propose new MXene (Ti 3 C 2 T X ) nano-sheet/Au nanostructure architectures to break through the limitations of the Raman detection with long-time stability. The MXene nanosheets with excellent biocompatibility can effectively prevent structural distortion from the interaction with the Au NSs, and can also guarantee a high enhancement effect owing to the spatially extended electromagnetic field distribution and electron injection into the molecules. The self-assembled Au nanostructures are aggregated based on the Volmer-Weber growth model, and the electromagnetic field distribution radically evolves depending on the morphologies of the resultant Au nanostructures, leading to a drastic compensation for the limited EE of the MXene nano-sheets. Consequently, the intensified Raman vibrational signals of R6G molecules lead to a high enhancement factor of 2.9 × 10 7 , even at an ultra-low concentration of 10 −10 M. Similarly, the Raman signals of the methylene blue (MB) and crystal violet (CV) molecules can also be detected at low concentrations below 10 −8 M, manifesting universal applications of the MXene/Au architectures for ultra-sensitive molecular detection under atmospheric conditions. SERS spectroscopy aims to augment the relatively weak molecular vibrations based on electromagnetic and chemical enhancement mechanisms, and offers a potential way for material identification, even up to the single-molecule level, under atmospheric conditions.