Sandwich-like Ag@Cu@CW SERS substrate with tunable nanogaps and component based on the Plasmonic nanonodule structures for sensitive detection crystal violet and 4-aminothiophenol

It is critical in nano physics nowadays to fabricate a superior surface enhanced Raman scattering (SERS) substrate which provides the high-density 'hot spots' for obtaining the strong local electric field. A sensitive, large-scale and low-cost sandwich-like Ag@Cu@CW SERS active substrate was successfully fabricated by decorating the Cu and Ag nanoparticles on the cicada wing (CW) with uniformly-distributed nanopillars via a simple method with the DC magnetron sputtering system. The SERS properties of the surface rough Ag@Cu@CW substrate with optimal nanogaps have been investigated in terms of the enhancement factor (EF, ~3.1369 × 10⁵), limit of detection (10⁻¹¹ M of 4-ATP), relative standard deviation (RSD, <15%) and sample-to-sample repeatability. The high-density 'hot spots' formed by the appropriate nanogaps and specific plasmonic nanostructures would give rise to stronger local electromagnetic field, which was also confirmed by the 3D finite-difference time-domain (3D-FDTD) simulation. For practical application, the crystal violet (CV) as the carcinogenic dyes used widely in the aquaculture were detected with the LOD of 10⁻¹⁰ M using our Ag@Cu@CW SERS substrate, suggested that the Ag@Cu@CW has a potential value in sensitive and quantitative detection of environment pollutant and chemical sensing.