Electrochemically induced Fenton reaction of few-layer MoS₂ nanosheets: preparation of luminescent quantum dots via a transition of nanoporous morphology

Abstract

Electrochemically induced Fenton (electro-Fenton) reaction was used for efficient and controllable preparation of hydroxyl radicals, leading to the generation of luminescent quantum dots through etching of as-exfoliated MoS2 nanosheets. Morphologic changes of MoS2 nanosheets during the electro-Fenton reaction were monitored using transmission electron microscopy, showing that etching of MoS2 nanosheets induced by hydroxyl radicals resulted in rapid homogeneous fracturing of the sheets into small dots via a transition of nanoporous morphology. The as-generated dots with vertical dimensional thickness of ca. 0.7 nm and plane size of ca. 5 nm were demonstrated to be MoS2 quantum dots (MoS2-QDs), and their photoluminescence properties were explored based on quantum confinement, edge effect, and intrinsic characteristics. Moreover, the degree of etching and the concomitant porosity of MoS2 nanosheets could be conveniently tuned via the electro-Fenton reaction time, resulting in a new morphology of nanoporous MoS2 nanosheets, with potential new applications in various significant areas.

Chemical Dissolution Pathways of MoS2 Nanosheets in Biological and Environmental Media

“…A recent review article presented a thermodynamic analysis suggesting that MoS 2 and other TMD nanosheet materials would be unstable to oxidative dissolution in O 2 -containing aqueous media, but no data were available to reveal if the kinetics are sufficiently fast for measureable degradation over relevant time scales. 7 If strong oxidizing agents such as hydroxyl radicals or H 2 O 2 are introduced, then etching of MoS 2 is indeed observed and leads to formation of MoS 2 quantum dots and soluble molybdenum species, 41 but of course these data are not directly relevant to the reaction with O 2 as the sole oxidant.…”

The use of tungsten disulfide dots as highly selective, fluorescent probes for analysis of nitrofurazone

“…These methods include liquid exfoliation [8,9], hydrothermal synthesis [10,11], pyrolysis [12], chemical vapor deposition [13] and electrochemical Li-intercalation [14]. TMDCs have a wide variety of mechanical and electronic applications with semiconductors of MoS 2 [15,16], MoSe 2 [17,18], WS 2 [19,20] and WSe 2 [21,22]. In particular, the WS 2 material consists of 2D covalently bonded S-W-S layers separated by a van der Waals gap.…”

Na‐Cation‐Assisted Exfoliation of MX2 (M = Mo, W; X = S, Se) Nanosheets in an Aqueous Medium with the Aid of a Polymeric Surfactant for Flexible Polymer‐Nanocomposite Memory Applications

“…The result insists that the Na‐assisted exfoliation did not cause the oxidation of MX 2 during the process. The peaks at 226.6, 163.4, and 162.2 eV are attributed to S 2s, S 2p 1/2 , and S 2p 3/2 photoelectrons of divalent sulfide ions . Na 1s photoelectron peak was detected at 1071 eV as well as Mo and S from as‐filtered samples, but Na was entirely removed after water washing.…”