Enhanced SERS Detection of Toxic Dyes Using Gold–Silver Core‐Shell Nanoparticles

Abstract Sensitive detection of organic pollutants in aqueous medium is crucial for environmental safety. In this regard, we demonstrate the surface‐enhancement Raman spectroscopy (SERS)‐based detection of organic dyes using Au–Ag core‐shell nanoparticles (NPs) prepared via a single‐step seed‐mediated method. This facile method allows straightforward optimization of Ag shell thickness on Au core by simply adjusting the concentration of silver nitrate in the growth solution. Subsequently, these NPs were employed for the SERS‐based trace detection of various organic dye pollutants, namely, crystal violet (CV), methylene blue (MB), and methyl orange (MO). The core‐shell NPs exhibited excellent sensitivity and enhancement of the Raman signal during organic dye detection. The SERS signal intensity was seen to depend sensitively on the Ag shell thickness and under optimal conditions, an experimental enhancement factor (EF) of 1.49 × 10 5 was obtained. Furthermore, detection limits of 10 −9 , 10 −7 , and 10 −6 M for CV, MB, and MO, respectively, were achieved. The SERS signal was also stable for 30 days owing to the combined effect of core‐shell structure formation and cetyltrimethylammonium bromide (CTAB) bilayer on NPs. To evaluate the potential of these core‐shell NPs in real‐world environmental applications, MB and MO dyes were detected in lake water samples.