Flexible Polymer-Supported 1T/2H-MoS₂@Au Hybrid Substrates with Synergistic Plasmonic-Chemical Enhancement for Trace...

Flexible and application-oriented surface-enhanced Raman spectroscopy (SERS) substrates are in high demand for trace-level molecular detection in complex environmental matrices. Herein, we report the development of a flexible hybrid SERS substrate supported on polydimethylsiloxane (PDMS), integrating phase-engineered 1T/2H-MoS₂ nanoclusters decorated with Au nanoparticles (denoted as PDMS@1T/2H-MoS₂@Au). Benefiting from the synergistic coupling between localized surface plasmon resonance (LSPR) of Au nanoparticles and charge-transfer-induced chemical enhancement from 1T/2H mixed-phase MoS₂, the as-fabricated substrate exhibits strong and tunable SERS responses under multiwavelength excitation. Systematic SERS performance evaluations demonstrate that the substrate achieves high sensitivity with a detection limit down to 10^-10 M for methylene blue (MB), excellent signal uniformity with a relative standard deviation (RSD) of 6.57%, and long-term stability with negligible signal degradation over 2 months, outperforming most flexible SERS substrates. Notably, multivariate analysis based on principal component analysis (PCA) reveals selective signal amplification toward MB in multicomponent dye systems, where the first principal component shows a strong correlation with the Raman fingerprint of MB. After spectral normalization, the PCA score plots further confirm the reliable molecular discrimination capability among multiple dye molecules. Importantly, the practical applicability of the flexible PDMS@1T/2H-MoS₂@Au substrate is validated by the trace-level detection of the pesticide thiram on real apple surfaces through conformal contact, achieving a detection limit as low as 10^-9 M. This work presents an application-focused sensing workflow, from the elucidation of the enhancement mechanism to real-sample analysis, highlighting the great potential of flexible MoS₂-Au hybrid SERS substrates for advanced environmental and food safety molecular sensing.