In Situ Functionalized Fluorescent WS₂-QDs as Sensitive and Selective Probe for Fe³⁺ and a Detailed Study of Its Fluorescence Quenching

Abstract

Most of the reports suggest that liquid exfoliated WS2-QDs are unstable; therefore the need of present day is to develop a novel synthesis route for producing long-term stable WS2-QDs. Herein, we report a bottom-up single-step hydrothermal growth of in situ functionalized blue fluorescent WS2-QDs with stable fluorescence in aqueous media without subsequent treatments. Presence of various functional groups over the surface of f-WS2-QDs provides high solubility and stability to f-WS2-QDs in aqueous media preserving its fluorescence. Further, photoluminescence property of f-WS2-QDs has been employed to devise an optical sensor with a high sensitivity (K D ∼ 104 M–1) and selectivity for ferric (Fe3+) ions. Under the optimal condition, response of the sensor is found to be linear in the range of 0–55 μM with a limit of detection (LOD) of 1.32 μM, which is within the maximum permissible level of Fe3+ (∼5.4 μM) in human drinking water by the USEPA. Further, we have also carried out a detailed evaluation on fluorescence quenching kinetics of f-WS2-QDs. Nonlinear behavior of S–V plot and TRPL measurements suggest that quenching is a mixed phenomenon of dynamic as well as static processes. Finally we have proposed a mechanism for fluorescence quenching of f-WS2-QDs in the presence of Fe3+.

Layered tungsten-based composites and their pseudocapacitive and electrocatalytic performance

“…The oxidised sulphate groups were generated from residues after reaction or intermediate products formed during the transformation of WS 2 from WO x . 20 The peak percentage areas for both S 2p 3/2 and S 2p 1/2 in the sample decreased with increased temperature from 400 to 800 °C, i.e. , WS_400 to WS_800.…”

Yellow Fluorescent Carbon Dots for Selective Recognition of As3+ and Fe3+ Ions

“…The photoexcited electrons cannot come back to the lower energy highest occupied molecular orbital (HOMO) of the C-dots; rather complexation occurs with the vacant 4p/3d orbital in the proximity of the As 3+ /Fe 3+ ions. Now, the electronic transition is forbidden from the 4p/3d orbital to the HOMO level, resulting in significant fluorescence quenching. , …”

“…Now, the electronic transition is forbidden from the 4p/3d orbital to the HOMO level, resulting in significant fluorescence quenching. 64,65 3.6. Solid-Phase Detection of As 3+ and Fe 3+ Ions.…”

Tungsten disulfide: synthesis and applications in electrochemical energy storage and conversion

“…[90] as tungsten sources, and thiourea (CH 4 N 2 S) [91], l-cysteine [92] and Na 2 S [93] as sulfur sources placed in a sealed system under certain temperature and pressure. By using hydrothermal/solvothermal strategies, various kinds of morphologies such as quantum dots [94,95], nanoparticles [96][97][98], nanosheets [99][100][101], nanotubes [102][103][104], nanorods [105,106], nanofibers [107], nanoflowers [108,109] and microspheres [110] could be successfully prepared (some of the representative morphologies are shown in Fig. 7a-h).…”