Oxygen-Tailored MoS2 as a High-Performance Substrate for Pressure-Induced Surface-Enhanced Raman Spectroscopy

Pressure-induced SERS (PI-SERS) has garnered increasing attention due to its applications in enhancing Raman signals under extreme conditions. However, the effective implementation of PI-SERS enhancement and the elucidation of its underlying mechanisms remain open questions. In this study, we introduce an innovative approach utilizing oxygen-tailored MoS2 as SERS substrates, significantly improving PI-SERS performance. This method enables the detection of trace dye molecules at ambient conditions and enhances SERS performance under high-pressure environments. Compared to MoS2, the oxygen-incorporated MoS2 (MoS1.4O1.6) substrate lowers the detection limit to 10-7 M of Rhodamine 6G (R6G) molecules and achieves a maximum enhancement factor (EF) of 1.53 × 106. Density functional theory (DFT) calculations reveal the significant intermolecular charge transfer (CT), which consequently results in pronounced Raman enhancement. The SERS performance of MoO3 substrates exhibits a gradual decrease with increasing pressure, with an abrupt increase observed at 8.49 GPa. This increase can be attributed to the resonant coupling between pressure-induced bandgap narrowing of MoO3 and the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of R6G molecules. This study provides new insights into the PI-SERS enhancement mechanism, offering promising perspectives for advancing SERS applications in high-pressure scenarios.