Solid-State Chemiresistors from Two-Dimensional MoS2 Nanosheets Functionalized with l-Cysteine for In-Line Sensing of Part-Per-Billion Cd2+ Ions in Drinking Water.
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ABSTRACT: Sensing of metal contaminants at ultralow concentrations in aqueous environments is vital in today's overpopulated world, with an extremely stringent limit (<5 ppb) for Cd2+ ions in drinking water. Here, we utilize sonochemically exfoliated molybdenum disulfide (MoS2) nanosheets functionalized with l-cysteine (Cys) as highly sensitive and selective two-dimensional (2D) materials for solid-state chemiresistors. We specifically targeted Cd2+ ions due to their high toxicity at low concentrations. MoS2-Cys nanosheets are fabricated using an ad hoc, low-complexity, one-pot synthesis method. Porous MoS2-Cys thin films with a high surface area are assembled from these nanosheets. Two-terminal chemiresistors incorporating MoS2-Cys films are demonstrated to be preferentially sensitive to Cd2+ ions at neutral pH, irrespective of other metal ions present in water flowing through the device. A 5 ppb concentration of the Cd2+ ions in the water stream increases the device resistivity by 20 times. Our devices operate at broad (1-500 ppb) range and fast (?1 s) response times. Cd2+ is selectively detected because of preferential, size-driven adsorption at the interstitials between l-cysteine functional groups, combined with pH-controlled charge transfer that removes electronic gap states from MoS2. MoS2-Cys-based chemiresistors can be deployed in-line to detect metal ions without any need for additional offline measurements.
SUBMITTER: Bazylewski P
PROVIDER: S-EPMC6964307 | biostudies-literature | 2020 Jan
REPOSITORIES: biostudies-literature
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