Two-dimensional FeS nanoflakes: synthesis and application to electrochemical sensor for mercury(II) ions

We report a facile solvothermal method to prepare troilite FeS two-dimensional nanoflakes. The morphology and size were observed by transmission electron microscopy (TEM), the intrinsic crystallography of the obtained FeS nanoflakes was characterized by powder X-ray diffraction and high-resolution TEM, and the composition was analyzed by X-ray photoelectron spectroscopy. Furthermore, the prepared FeS nanoflakes were successfully modified on an electrode to fabricate a sensor for Hg²⁺ detection. The electrochemical detection mechanism was expected that Hg²⁺ ions interact with FeS to form stable HgS in the nanoflakes, which provided a sensitive approach for electrochemical detection of Hg²⁺ selectively. The detection limit for Hg²⁺ was 4 nM in a PBS solution. The prepared sensor based on the FeS nanoflakes shows the better performance than that with bulk-FeS materials for the Hg²⁺ detection. The proposed FeS nanoflakes also exhibit good applicability for monitoring Hg²⁺ in real water specimens.