Layer-by-layer Thin Film of Ti3C2 MXene and Gold Nanoparticles as an Ideal SERS Platform

The combination of plasmonic metals and MXene, as a new and interesting member of the 2D material class, may provide unique advantages in terms of low cost, versatility, flexibility, and improved activity as an ideal surface-enhanced Raman spectroscopy (SERS) platform. Despite the recent progress, the present studies on the utilization of plasmonic metal/MXene-based SERS systems are quite limited and thereby benefits of the extraordinary properties of this combination cannot be realized. In this study, for the first time, we propose layer-by-layer (LbL) thin films of Ti3C2 MXene and gold nanoparticles (AuNPs) as a robust SERS platform (Ti3C2/AuNPs). For this, Ti3C2 MXene was synthesized from the Ti3AlC2 MAX phase, and the Ti3C2/AuNP LbL film was fabricated via a vacuum-assisted filtration method to create consecutive layers of each material. This procedure produced densely distributed AuNPs in the LbL film in a well-controlled manner. The SERS activity tests for methylene blue and DTNB as Raman reporter molecules showed that they exhibited enhancement factors of 1.5 × 106 and 1.2 × 106 and limits of detection of 1 × 10-8 M, and 2.5 × 10-8 M, respectively. Various mechanisms, including the formation of hotspots due to AuNPs on the interlayer of Ti3C2, improved surface roughness and resultant optical activity, as well as the synergistic effect between Ti3C2 and AuNPs, contributed to the resultant SERS activity to some extent. This study has proven the feasibility of the Ti3C2/AuNP LbL system as a robust SERS-based sensor platform, paving the way for its use in various biological and chemical applications.