A one-step colorimetric method of analysis detection ofHg2+ based on an in situ formation of Au@HgS core–shell structures

Abstract

A new approach for the detection of Hg²⁺ is reported based on color changes from which gold nanoparticles (Au NPs) are surrounded by a layer of HgS quantum dots to form in situ Au@HgS core–shell nanostructures. The surface plasmon resonance (SPR) absorption of the gold core was changed due to a shell layer of HgS formed on the surface of the Au NPs, which brings the colour change of the aqueous solution. Therefore, Hg²⁺ can be recognized by visualizing the colour change of the Au@HgS core–shell nanostructures, and can be detected quantitatively by measurement of the UV-vis spectra. Some effects on the detection of Hg²⁺ were investigated in detail. This method was used to detect Hg²⁺ with excellent selectivity and high sensitivity. In our method, the lowest detected concentrations for mercury ions were 5.0 × 10⁻⁶ M observed by the naked eye and 0.486 nM as measured by UV-vis spectra. At the range from 8.0 × 10⁻⁵ to 1.0 × 10⁻⁸ M of Hg²⁺, this method was shown to have a good linear relationship.