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.