Temperature-Modulated VO₂/Au Composite Nanoparticles for High-Performance SERS-Based Trace Detection

The nanoscale surface of the substrate is crucial for the molecule detection in surface-enhanced Raman spectroscopy (SERS) technology. In this work, we propose a VO2/Au composite nanoparticle structure as a high-performance SERS substrate, which was fabricated through a combination of evaporation coating, annealing, and spin coating. The Raman enhancement factor (EF) for rhodamine 6G (R6G) molecules reaches 4.4 × 109 with a minimum detection concentration of 10–10 M and the relative standard deviation (RSD) is only 12.9%. The results show that the nanoengineered substrate exhibits exceptional Raman activity at 20 °C, attributed to plasmonic hotspots and charge transfer mechanisms. When the temperature increases to 80 °C, the phase transition of VO2 is induced, leading to a weakening of the charge transfer. This enables the in situ modulation of the SERS signal. The VO2/Au composite nanoparticle structure prepared in this work exhibits strong Raman enhancement performance and in situ modulation of the SERS signal intensity, which shows great potential for applications in trace detection.