Selective sensing of Hg2+ ions by optical and colorimetric methods using gold nanorods embedded in a functionalized silicate sol–gel matrix

Abstract

A simple method was developed for the preparation of gold nanorods embedded in an amine functionalized silicate sol–gel matrix (Au–TPDT NRs) in an aqueous medium and its application towards optical sensing of mercuric (Hg²⁺) ions was demonstrated. A colorimetric sensor was developed for Hg²⁺ ions using the Au NRs embedded in an amine functionalized silicate sol–gel matrix. The optical and colorimetric detection of Hg²⁺ ions was carried out using the Au NRs embedded in a functionalized silicate sol–gel matrix based on the localized surface plasmon resonance (LSPR) of the Au NRs and the absorption spectra showed a significant blue shift in the LSPR band upon addition of Hg²⁺ ions. It was observed that the addition of optimum concentration of Hg²⁺ ions into the Au–TPDT NR solution led to a decrease in the intensity of the LSPR band and the color changed due to change in the morphology of Au NRs through formation of an AuHg amalgam. The selective detection of Hg²⁺ ions using the Au–TPDT NRs in the presence of other environmentally relevant metal ions was reported by optical and colorimetric methods. This method was successfully applied for the determination of Hg²⁺ ions in real water samples.