Silver nanomaterials sensing of mercury ions in aqueous medium

Heavy metal ions pollution has become a critical issue around the world. In order to develop highly efficient and accurate nanosensor at low cost, the application of nanomaterials for inorganic toxic elements (e.g. Hg2+, Pb2+, Cd2+, Cr6+, As3+/As5+, Cu2+) remediation and sensing has attracted significant attentions in academia and industry. In this review article, the application of Ag nanomaterials (Ag NMs) for colorimetric and fluorescent sensing of Hg2+ ions in aqueous medium has been summarized. Two plausible mechanisms for Ag NMs sensing Hg2+ ions have been proposed, namely, Hg2+ oxidization Ag(0) of Ag NMs to form Ag/Hg amalgam, and Hg2+ coordination with functional groups (e.g. -SH, -OH, -NH2, -COOH) of surface stabilizing organic molecules of Ag NMs. The resulted aggregation of Ag NMs, spectra shift of UV-vis absorption, as well as visual color changing have been utilized for the sensing of Hg2+ in aqueous medium. Various organic, inorganic and nanomaterial stabilizers, particularly natural products from plant extracts, have been systematically summarized for developing commercially available field-test Ag NMs-based nanosensor with high sensitivity and selectivity. (c) 2021 Elsevier B.V. All rights reserved.