Green synthesis of Cu@Ag core–shell nanoparticles as efficient colorimetric sensing for Hg(II) ion

Cu@Ag nanoparticles (NPs) were synthesized using the aqueous extract of Citrus paradisi peel as a reducing and stabilizing agent. The Cu@Ag NPs were confirmed by FT-IR, XRD, UV–Vis, EDX, FE-SEM, and EDX mapping. The Cu@Ag NPs-based colorimetric sensor was utilized for rapid and simple detection of Hg 2+ ions in water. With adding Hg 2+ ions to Cu@Ag NPs solution, the color of the solution changed from yellow to pink. The absorption band decreases at 411 nm and the second absorption band appears at 492 nm. The detection limit for Hg 2+ ions was determined as 5 × 10 −6 M. Sensitivity and selectivity colorimetric sensors were studied toward other metal ions (Ca 2+ , Hg 2+ , Ba 2+ , Mn 2+ , Mg 2+ , Ni 2+ , Zn 2+ , Co 2+ , Fe 2+ , Cd 2+ , Pb 2+ ). It was found that these ions do not interfere with the detection of Hg 2+ ions. This method of detection was successfully used to detect Hg 2+ ions in an aqueous solution.