Fabrication of Long-Range Film of Flower-Like Ag Nanoparticles for Highly Sensitive SERS Substrate

The fabrication of sensitive and homogeneous surface-enhanced Raman scattering (SERS) substrates is the key to its practical application. In this paper, flower-like silver nanoparticles (Ag NPs) were successfully synthesized in water/ethanol/n-octanol emulsions by an assistant of citric acid and sodium citrate. The size and surface roughness of flower-like Ag NPs can be adjusted by changing the experimental parameters, such as the ratio of citric acid to sodium citrate, and the concentration of ascorbic acid. The resulting flower-like Ag NPs were constructed to form a homogeneous single-layer film by a three-phase interfacial self-assembly method. The performance of the film as SERS substrate was investigated using Rhodamine 6G as a probe molecule, and the enhancement factor was as high as 2.7 × 10 7 . In addition, the SERS substrate exhibits excellent repeatability, with a relative standard deviation of 6.5% for point-to-point Raman intensity changes. The current research will provide a new strategy for SERS sensors in food, environment, and medical applications.