Facile fabrication of PS/Cu₂S/Ag sandwich structure as SERS substrate for ultra-sensitive detection

In this work, a serials of PS(polystyrene)/Cu₂S/Ag sandwich substrates were successfully constructed using the magnetic sputtering method by adjusting the Ag sputtering time (0 min, 2 min, 4 min, 6 min, 8 min and 10 min) and used as the surface-enhanced Raman scattering (SERS) substrates. When the Ag sputtering time was 6 min, the strongest SERS signal was observed. The optimized SERS substrate has strong SERS activity on 4-mercaptobenzoic acid (4-MBA), the minimum detection limit was 10^-13 M and the enhancement factor was as high as 4.7 × 10⁷. In addition, the SERS signals were highly reproducible with small standard deviation. The SERS enhancement mechanism of the PS/Cu₂S/Ag system was attributed to the synergistic effect of the chemical mechanism and the electromagnetic enhancement mechanism. This strategy has find a new way for manufacturing SERS activity sensor with high sensitivity and reproducibility.