Au-Ag Nanoparticles with Controllable Morphologies for the Surface-Enhanced Raman Scattering Detection of Trace Thiram

Surface-enhanced Raman scattering (SERS) technique has been limitedly applied to the detection of trace thiram due to the weak activity of employed substrates. In this work, Au-Ag nanoparticles (NPs) with controllable morphologies are synthesized and used as SERS-active substrates for the detection of trace thiram. Porous-spiny Au-Ag NPs are synthesized with spherical Ag NPs as intermediates through in situ redox. Annular Au-Ag NPs can be further obtained by heating porous-spiny Au-Ag NPs. Here, the morphology transformation of Au-Ag NPs is first completed by means of the element diffusion theory, providing a strategy for the morphology control of complex Au-Ag NPs. Additionally, these Au-Ag NPs with optimized morphologies were chosen as substrates for the successful SERS detection of trace thiram. Especially, porous-spiny Au-Ag NPs show superior sensitivity and reproducibility. Meanwhile, using porous-spiny Au-Ag NPs as SERS-active substrates, thiram can be quantitatively detected in the range from 10-3 to 10-11 M. Thus, it is inferred that Au- Ag NPs with optimized morphologies will have great potential in the field of trace analyte detection related to food safety and environmental protection.