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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