Selective tellurium nanowire-based sensors for mercury(II) in aqueous solution

Abstract

We have developed a simple, colorimetric, and label-free tellurium nanowire (Te NW)-based probe for the detection of mercury ions (Hg(II)) in aqueous solution, operating on the principle of strong hybridization and galvanic replacement reaction of Te-Hg. The Te NWs (length: 920 nm; diameter: 20 nm) reacted with Hg(II) to induce dissolution and aggregation of the TeNWs. As a result, the absorption band of the Te NWs in a solution undergoes a decrease in the presence of Hg(II). Energy-dispersive X-ray spectroscopy and surface-assisted laser desorption/ionization measurements demonstrated the presence of Hg on the Te NWs. The Te NWprobe specifically and sensitively detected Hg(II) ions under optimal concentrations of pH, temperature, and sodium dodecyl sulfate (SDS) concentration.When using a mixture of Te NWs (3.0 nM) and SDS (5 μM) in 5 mMsodium phosphate (pH 4) at 50 °C, this sensor provides a limit of detection of 0.5 nM for Hg(II) (signal-to-noise ratio of 3) with high selectivity (at least 100 fold over other metal ions). Our approach abrogates the need for complicated chemosensors or sophisticated equipment. This cost-effective sensing system allows the rapid and simple determination of the concentrations of Hg(II) ions in real samples (in this case, river, lake, and tap water samples).