Visual sensing of Hg 2+ using unmodified Au@Ag core–shell nanoparticles

摘要

In this work, we have developed a novel visual Hg_(2+)sensor in aqueous solution using unmodified Au@Ag core–shell nanoparticles at room temperature, based on a redox reaction between Ag-shell and Hg_(2+). The prepared Au@Ag core–shell nanoparticles exhibited good monodispersity. In the presence of Hg_(2+), Hg_(2+)was reduced into Hg (0) by Ag-shell, and deposited on the surface of Au-core to form Au–Hg alloys and caused nanoparticles aggregation, leading to the color changes of the solution from yellow to purplish red, and the surface plasmon resonance spectra of Au@Ag core–shell nanoparticles red shift. Under the optimal conditions, the visual sensor could selectively detect Hg_(2+)as low as 0.4?μM with the naked eye and 5.0 nM by UV–vis spectra analysis methods. The designed sensor had several advantages: (1) the nanoparticles surface need not be functionalized. (2) The color change of the solution was in 2?s and could easily be observed with naked eyes. The visual sensor had been applied to detection of Hg_(2+)in tap and lake water, which obtained satisfied result.