A flexible dual-mode EC-SERS sensor of SPE/RGO/Au@Ag film for sensitively detecting thiram residues on fruit peels

The presence of thiram residues on fruit peels posed a significant risk to human health. Here, we prepared an electrochemical surface-enhanced Raman spectroscopy (EC-SERS) sensor of SPE/RGO/Au@Ag flexible film to detect thiram residues on fruit peel. The surface of this film was evenly covered with Au@Ag nanoparticles, which allowed it to specifically identify thiram residues through the formation of Ag-S bond. In addition, an electrochemical method was used to modulate the energy level matching between the SERS film and the thiram molecules to improve the chemical enhancement effect of the SERS. The results indicated that the charge transfer degree between the SERS film and the thiram molecules was up to 0.875. The SPE/RGO/Au@Ag film achieved a limit of detection (LOD) of 2.1 pM at -1.3 V. Owing to its excellent SERS performance, the SPE/RGO/Au@Ag film could successfully recognize the thiram residues on apple and orange peels, with recoveries of 91% to 107% and from 89% to 102%, respectively. The flexible EC-SERS sensor offers considerable promise for sensitively recognizing thiram residues on fruit peels.