Superhydrophobic PP-Si@AgNPs as a high-performance SERS substrate

A three-dimensional superhydrophobic porous pyramidal silicon decorated with silver nanoparticles was developed for high-performance SERS detection. • The hierarchical porous structure enhances light absorption and plasmonic “hot spots”. • The superhydrophobic surface enables efficient analyte enrichment by reducing the droplet contact area and mitigating the coffee-ring effect. • The substrate exhibits excellent sensitivity, high enhancement factor, and outstanding reproducibility. • It was successfully applied for the sensitive detection of trace pollutants in real samples. Surface-enhanced Raman scattering (SERS) enables label-free detection with molecular fingerprinting, but its application is often limited by complex fabrication processes and nonuniform signal distributions. To address these issues, we developed a three-dimensional superhydrophobic substrate consisting of porous pyramidal Si decorated with silver nanoparticles (PP-Si@AgNPs). Compared with the conventional Si@AgNPs and Py-Si@AgNPs, the hierarchical structure enhances light absorption to 78% at 532 nm and increases the specific surface area exposed under the laser spot. The superhydrophobic surface (152.6°) reduces the droplet contact area by 88.6%, increasing the surface density of analyte molecules by 8.8-fold and enhancing the SERS intensity by 7.85-fold. Using rhodamine 6G as a probe molecule, the substrate presents a detection limit of 10 −13  M and an enhancement factor of 5.85 × 10 9 . The relative standard deviations of 3.34% and 6.39% indicate excellent spot-to-spot and batch-to-batch reproducibility. Moreover, the substrate enables low-concentration detection of malachite green in fish skin extract (7.8 × 10 −11  M), thiram in apple extract (1.6 × 10 −8  M), and melamine in milk (1.0 × 10 −8  M), highlighting strong potential for practical analytical applications. Download: Download high-res image (50KB) Download: Download full-size image