Surface-enhanced Raman scattering sensor of MoS2/Au@Ag film to detect the thiram residues in citrus

This study presents a surface-enhanced Raman scattering (SERS) sensing platform based on a MoS 2 /Au@Ag heterojunction for specifically detecting the residues of thiram pesticide. A Nano-MoS 2 film was firstly prepared by depositing MoS 2 nanosheets on the surface of a stainless steel sheet. Subsequently, Au nanoparticles and Ag nanoparticles were deposited on the surface of MoS 2 film to form a MoS 2 /Au@Ag heterojunction for SERS application. This well-performing SERS substrate was originated from the synergistic effect of electromagnetic (EM) enhancement and chemical (CM) enhancement to boost its SERS signal. Here, the CM contribution could be up to 41.8 % in the process of optimizing interfacial charge transfer (CT) pathways in MoS 2 /Au@Ag heterojunction. Thus, the SERS sensor based on MoS 2 /Au@Ag film showed an excellent signal homogeneity (RSD = 4.36 %) and an ultrahigh sensitivity to thiram molecules with a limit of detection (LOD) as low as 0.32 nM. Moreover, it could also recognize the thiram residues at 10 nM level in citrus peels, with a recovery rate of 91.0–109.0 %. The SERS sensor we developed in this study has a high sensitivity, excellent reproducibility, and long-term stability, which could be widely applied for the food safety monitoring