Fig. 1. Preparation process of CNTs-FAgNPs substrate

Fig. 2. Morphology and structure of CNT-FAgNPs

Fig. 3. XRD，UV-Vis and XPS patterns of FAgNPs and CNT-FAgNPs

Fig. 4. SERS spectra of R6G

Fig. 5. Study on long-term stability of SERS substrate

Fig. 6. SERS sensitivity detection of furfural

Fig. 7. Quantitative analysis method for SERS detection of furfural in transformer oil and study on repeatability of SERS substrate