Synthesis and Application of Cu@Ag Bimetallic Hetero-Nanoflower Structures with High SERS Performance

The fabrication of surface-enhanced Raman scattering (SERS) substrates with high hotspot density and superior sensitivity is a critical bottleneck limiting their practical applications. In this paper, a three-dimensional (3D) SERS substrate based on high-density Cu@Ag bimetallic heterostructured nanoflowers (Cu@Ag NF) was constructed using citric acid etching-assisted electrochemical deposition (ED) technology and high-vacuum electron beam evaporation coating technology, which provides an efficient and low-cost preparation process for the SERS substrate. The performance of a Cu@Ag 3D-SERS substrate was evaluated systematically using crystal violet (CV) as the probe molecule. This substrate exhibited a limit of detection (LOD) as low as 10–12 M (pM), and the signal intensities at its five characteristic peaks were more than 10 times higher than those of the Ag@ITO substrate, indicating its high sensitivity. In addition, the substrate demonstrated excellent uniformity (relative standard deviation (RSDs) < 11% for 15 randomly tested points) and long-term stability (no significant signal attenuation after 2 weeks of storage at room temperature). This work provides valuable guidance for the facile, scalable, and low-cost fabrication of high-performance SERS substrates, and presents a reliable strategy for the detection of trace organic pollutants in practical scenarios.