Ag@WS2 quantum dots for Surface Enhanced Raman Spectroscopy: Enhanced charge transfer induced highly sensitive detection of thiram from honey and beverages

Novel SERS substrates is urgently in demand for rapid and sensitive analysis of toxic agrochemicals from food. In this work, a monodispersed tungsten disulfide quantum dots modified silver nanosphere (Ag@WS(2)QD) was prepared and used as SERS substrate. Ag@WS(2)QD generated uniform and stable SERS signals within 2 min, displaying great promise in mixing and reading detection. Compared to unmodified colloidal silver nanoparticles, 4 times higher analytical enhancement factor was found in Ag@WS(2)QD. Density functional theory calculation verified the enhanced charge transfer within the coupling systems of molecule-Ag@WS(2)QD. Besides, the unique surface properties are beneficial for the enrichment of specific molecule. Both the chemical extraction and enhanced charge transfer contributes to rapid and sensitive SERS detection of Ag@WS(2)QD. A mixing and reading SERS method for thiram from honey and four kinds of juice was developed from Ag@WS(2)QD, showing great promise for rapid and direct SERS detection for toxic agrochemicals and further applications.

Automated summary

This study developed novel SERS substrates using monodispersed tungsten disulfide quantum dots modified silver nanospheres (Ag@WS(2)QD) for rapid and sensitive analysis of toxic agrochemicals. Ag@WS(2)QD showed uniform and stable SERS signals within 2 minutes, with a 4 times higher analytical enhancement factor compared to unmodified colloidal silver nanoparticles. Enhanced charge transfer and unique surface properties contribute to the rapid and sensitive SERS detection using Ag@WS(2)QD.