Charge-transfer-driven ultrasensitive SERS sensing in a two-dimensional titanium carbonitride MXene.

Two-dimensional (2D) MXenes stand out as promising platforms for surface-enhanced Raman scattering (SERS) sensing owing to their metallic feature, various compositions, high surface area, compatibility with functionalization, and ease of fabrication. In this work, we report a high-performance 2D titanium carbonitride (TiCN) MXene SERS substrate. We reveal that the abundant electronic density of states near the Fermi level of TiCN MXene boosts the efficiency of photo-induced charge transfer at the interface of TiCN/molecule, resulting in significant Raman enhancement. The SERS sensitivity of TiCN MXene is further promoted through a 2D morphology regulation and molecular enrichment strategies. Moreover, prohibited drugs are detectable on this substrate, presenting the potential of trace-amount analysis on TiCN MXene. This work provides a deep insight of the SERS mechanisms of TiCN MXene and broadens the practical application of transition metal carbonitride MXene SERS substrates.