La,S-CeO₂/Ag-based reusable SERS substrate for simultaneous detection of multiple hazardous molecules

This study presents a three-dimensional, bowtie-like La, S co-modified CeO₂/Ag composite as a high-performance, reusable surface-enhanced Raman scattering (SERS) substrate. The substrate demonstrates exceptional sensitivity for Congo red (CR) with a low detection limit of 10^-11 M, an enhancement factor of 4.3 × 10⁷, and a wide linear response (R² = 0.997). It also exhibits excellent reproducibility (RSD = 3.25%) and remarkable long-term stability, retaining ∼90% of its initial SERS activity after three months. The superior performance is attributed to a synergistic enhancement mechanism, where the unique architecture provides dense electromagnetic hot spots, and the La-S co-modification optimizes the electronic structure to facilitate efficient charge transfer. Its practical utility is demonstrated through the detection of various pollutants, such as tetracycline (10^-11 M) and thiram, even in spiked lake water (10^-10 M). Significantly, the integrated photocatalytic self-cleaning function endows the platform with excellent reusability, with the SERS signal for CR and thiram retaining ∼83% and ∼76% respectively after five detection-degradation cycles. This work provides an effective strategy for developing multifunctional, reusable SERS substrates through structural and compositional engineering, showcasing great potential for applications in environmental monitoring and analytical science.