Quasi-metal 2D Ag2Te nanosheets for high performance surface-enhanced Raman scattering detection
Semiconductor-based surface-enhanced Raman scattering (SERS) substrates have attracted significant attention due to their high uniformity, reproducibility, stability, and cost-effectiveness. However, the Raman enhancement in semiconductors primarily relies on the chemical mechanism (CM), which typically results in a lower enhancement capability compared to traditional noble metals. In this study, we developed a novel two-dimensional (2D) SERS substrate, Ag2Te nanosheets (NSs), synthesized through a simple one-step redox reaction utilizing 2D Te NSs as the template. The 2D Ag2Te NSs not only exhibit strong interfacial interactions with molecules, thereby supporting the CM, but also possess quasi-metallic properties with low resistivity (2.8 × 10−4 Ω cm) and high density of free electrons (4.15 × 10^22 cm−3), giving rise to a significant visible-region surface plasmon resonance (SPR) band and contributing to enormous electromagnetic mechanism (EM). By synergizing CM and EM, the 2D Ag2Te NSs SERS substrate achieved an ultra-low limit of detection (LOD) of 10−10 M with an enhancement factor (EF) of 2.6 × 10^7 for methylene blue (MB), outperforming most semiconductors, even rivaling noble metals. The quasi-metallic properties of 2D Ag2Te NSs also benefit their sensitivity to multiple molecules. The accuracy and reliability were demonstrated in real-sample detections with recoveries of 91.5%–108.3% for various target molecules. These excellent performances, combined with remarkable cost-effectiveness, demonstrate the potential of 2D Ag2Te NSs as a practical SERS substrate with broad applicability. Furthermore, the inherent structural simplicity of these nanosheets creates significant opportunities for further sophisticated nanostructural engineering to advance the SERS performance in the future.