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Cobalt compounds; Cobalt metallography; Electronic structure; Heavy metals; High resolution transmission electron microscopy; Hydrophilicity; Ligands; Metal ions; Metal nanoparticles; Morphology; Nanosensors; Nickel compounds; Nickel metallography; Optical correlation; Optical properties; Silver alloys; Silver metallography; Silver nanoparticles; Synchrotron radiation; X ray absorption spectroscopy; X ray photoelectron spectroscopy, Alloy nanoparticle; Coordination compounds; Functionalized; Morphological analysis; Nano-structured; Negatively charged; Silver nanoparticle (NPs); State of the art, Mercury compounds
Abstract:
In this work, the electronic and molecular structure, as well as the morphology, of innovative nanostructured materials whose optical properties respond to the presence of heavy metals in water samples was investigated. In particular, the here discussed silver nanoparticles (NPs) stabilized by a hydrophilic ligand (sodium 3-mercapto-1-propanesulfonate, 3MPS) are able to reveal the presence of mercury ions at ppm levels. The sensitivity of the proposed nanosensor to Hg(II) in 1-5 ppm range was ascertained by optical tests; then, the local chemistry and electronic structure of the nanostructured coordination compounds made of functionalized silver nanoparticles (NPs) and metal ions, and their correlation with the resulting nanoaggregates' shape and morphology, were investigated by state-of-the-art synchrotron radiation (SR)-induced spectroscopies and transmission electron microscopy (TEM). In particular, SR-induced X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) measurements allowed us to gather complementary information about the silver-mercury interaction, which is only partially mediated by the negatively charged 3MPS ligand, different from what was observed for analogous nanosensors applied to other bivalent heavy metal ions, for example, Co(II) and Ni(II). TEM morphological analysis sheds light on the structure of the AgNP-3MPS/Hg aggregates, revealing the formation of Ag/Hg alloy nanoparticles. © 2020 ACS. All rights reserved.
