Two-dimension Flower-Shaped Au@Ag Nanoparticle Arrays as Effective SERS Substrates with Highly Sensitivity and Reproducibility for Detection of Thiram
A simple and controllable route is presented for construction of two-dimension (2D) flower-shaped Au@Ag nanoparticle (NP) arrays through in-situ chemical reduction growth of Ag nanosheets on the Au NP arrays. Such micro/nanostructured arrays composed of interlaced Ag nanosheets can act as a good candidate for SERS substrate due to a lot of “hot spots” generated by the rough surface of the nanosheets and small nanogaps less than 10 nm between the Au@Ag NPs. After optimizing the experimental parameters (the array periodicity of 500 nm and the growth time of 20 min), the flower-shaped Au@Ag NP array as a SERS substrate has a low detection limit (10-11 M) of thiram, which is commonly used pesticide molecules and causes environmental pollution due to the excessive use. They also exhibit very good SERS signal uniformity and repeatability (RSD≈7.4%) because abundance of “hot spots” and highly ordered structures on a large scale. Such 2D flower-shaped Au@Ag NP arrays with economical preparation and excellent SERS property are meaningful for the practical applications of organic molecular Raman detection.