Vacuum-assisted thermal evaporation deposition for the preparation of AgNPs/NF 3D SERS substrates and their applications

Herein, a 3D SERS substrate based on nickel foam (NF) and silver nanoparticles (AgNPs/NF 3D SERS) was synthesized using vacuum-assisted thermal evaporation deposition. The performance of the AgNPs/NF 3D SERS substrate was investigated using rhodamine 6G (R6G) as a probe molecule at different AgNP deposition levels. The highest sensitivity of the substrate with a limit of detection (LOD) of 10−9 M and an enhancement factor (EF) of 1.56 × 106 was achieved when the optimal amount of AgNPs was reached. Moreover, the use of R6G at 10−6 M concentration as the probe molecule ensured the relative standard deviation (RSD) of 9.2% for the AgNPs/NF 3D SERS substrate, and its SERS performance hardly decreased after 30 days of placement at room temperature, which evidenced that the prepared SERS substrate had favorable stability and repeatability. Finally, the substrate was used to analyze carbendazim in deionized and river water in two different environments. The results revealed that the LOD of CBZ was as low as 10−7 M under both conditions, and there was a good linear relationship between the CBZ concentration and the SERS signal intensity (R2 = 0.955 and 0.927, respectively), which demonstrated the great potential of AgNPs/NF 3D SERS substrates for pesticide residue identification in practical analysis.