Optimization of SERS performance via solid substrate morphology modulation

Three-dimensional surface-enhanced Raman scattering (SERS) substrates exhibit superior enhancement performance compared to their two-dimensional counterparts, however, the effect of support morphology on SERS activity remains unclear. Here, we fabricated gold trioctahedra (Au TOH) featuring multiple sharp tips and edges, and transferred their monolayer onto silica wafers, polystyrene (PS) sphere arrays and microbowl arrays through interfacial self-assembly and wet-inverted transfer strategy. The effects of Au TOH size and substrate morphology on SERS performance were systematically investigated using 4-mercaptobenzoic acid (4-MBA) as the probe molecule. Expectedly, Au TOH monolayers on PS sphere arrays and microbowl arrays exhibits 6.23- and 4.26-fold higher SERS signal than their planar counterparts, which was verified by the finite-different time-domain simulation. The largest Au TOH-based PS sphere arrays achieved the strongest SERS performance with an enhancement factor of 1.03 × 10⁷, along with excellent signal homogeneity, batch-to-batch reproducibility, and temporal stability. The designed SERS substrate enables sensitive detection of thiram in tea samples at a concentration as low as 2.5 × 10^-6 M. Over all, this work advances the understanding of how support morphology modulates SERS enhancement and paves a new strategy for engineering ultrasensitive SERS platforms for practical applications.