Development of silver/gold nanocages onto indium tin oxide glass as a reagentless plasmonic mercury sensor

•A reagentless, sensitive and selective optical sensor for detection of Hg(II) was developed.•Silver–gold nanocages were prepared on the transparent indium tin oxide coated glass surface.•The nanomaterials could act as optical sensing probe as well as reducing agent.•The plasmonic sensor could be used to detect mercury ions in field analysis.

We demonstrate the utilization of silver/gold nanocages (Ag/Au NCs) deposited onto transparent indium tin oxide (ITO) film glass as the basis of a reagentless, simple and inexpensive mercury probe. The localized surface plasmon resonance (LSPR) peak wavelength was located at ∼800 nm. By utilizing the redox reaction between Hg2+ ions and Ag atoms that existed in Ag/Au NCs, the LSPR peak of Ag/Au NCs was blue-shifted. Thus, we develop an optical sensing probe for the detection of Hg2+ ions. The LSPR peak changes were lineally proportional to the concentration of Hg2+ ions over the range from 10 ppb to 0.5 ppm. The detection limit was ∼5 ppb. This plasmonic probe shows good selectivity and high sensitivity. The proposed optical probe is successfully applied to the sensing of Hg2+ in real samples.

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