Hierarchical nanoarchitectonics with three-layer (Ag/Ag 2 O/Ag) spherical nanoarrays with highly sensitive SERS performance

In recent years, multilayer metal arrays have received much attention in the fabrication of surface-enhanced Raman scattering (SERS) substrates. In this study, we prepared three-layer spherical nanoarrays by depositing double layers of Ag on hexagonal close-packed polystyrene (PS) sphere arrays and oxidizing the bottom layer of Ag to form oxide layer at ambient conditions, obtaining Ag/Ag 2 O/Ag three-layer spherical nanoarrays. By optimizing the thickness of silver layers and medium oxide layer, the SERS activity can be enhanced effectively. Using R6G molecule as the analyst, the SERS enhancement factor of the substrate can be up to 3.93 × 10 7 , indicating that the substrate has high SERS sensitivity. It was found by the experiment that the SERS performance of the three-layer Ag nanosphere array was about 5.2 times stronger than that of the single-layer Ag nanosphere array with the same thickness, and it had good reproducibility and uniformity. It shows that ultra-thin oxide layer in the three-layer structure played a key role in SERS enhancement.