Strongly luminescent monolayered MoS2 prepared by effective ultrasound exfoliation

Abstract

Intense ultrasound in a pressurized batch reactor was used for preparation of monolayered MoS2 nanosheets from natural mineral molybdenite. Exfoliation of bulk MoS2 using ultrasound is an attractive route to large-scale preparation of monolayered crystals. To evaluate the quality of delamination, methods like X-ray diffraction, Raman spectroscopy and microscopic techniques (TEM and AFM) were employed. From single- or few-layered products obtained from intense sonication, MoS2 quantum dots (MoSQDs) were prepared by a one-pot reaction by refluxing exfoliated nanosheets of MoS2 in ethylene glycol under atmospheric pressure. The synthesised MoSQDs were characterised by photoluminescence spectroscopy and laser-scattering particle size analysis. Our easy preparation leads to very strongly green luminescing quantum dots.

Fabrication of blue luminescent MoS 2 quantum dots by wet grinding assisted co-solvent sonication

“…For the synthesis of strong photoluminescence MoS 2 QDs, the exfoliation of bulk MoS 2 to monolayer is a pre-requisite and important step. When the size of the exfoliated mono layer MoS 2 is less than 100 nm, it leads to the confinement and edge effects which causes the photoluminescence emission [40]. Due to the transition from indirect to direct band gap MoS 2 nanostructures show unique photoluminescence properties.…”

“…We also used this strategy to synthesize MoS 2 QDs using bath and probe sonication in NMP and DCB and it was found to be an efficient method because the concentration (yield) of the as synthesizedMoS 2 QDs was found to be 7mg mL -1 . During sonication, the increase in temperature and pressure of the solution results the generation of hydrodynamic forces which cleave larger particles into smaller particles [40].…”

Fast and Straightforward Synthesis of Luminescent Titanium(IV) Dioxide Quantum Dots

“…Each Ti oxide is also a component in O 1s but the reliable literature data are rather poor for some of the oxides. The elsewhere reported shift in Ti 2p between Ti4+ and Ti3+ is from 1.2 eV [16] up to 1.6 eV [17,18] and between Ti4+ and Ti2+ from 2.4 eV [12] up to 3.1 eV [15]. The reported BE of components varies in the literature due to the calibration process and the charging effect.…”

“…The bulk sample was exfoliated using high intensity ultrasound in the pressurized reactor and obtained nanosheets form with ethylene glycol under reflux at temperature 198 ∘ C quantum dots [11][12][13]. In this paper, we for the first time presented fast, simple, and scalable bottom-up method for synthesis luminescent titania quantum dots TiQDTs from titania oxosulphate and hydrazine hydrate as coupling agents and ethylene glycol, dimethyl sulfoxide, octadecene, dodecanethiol, dimethylformamide, and tetraethyl orthosilicate as solvents.…”

Fabrication of novel heterostructured few layered WS2-Bi2WO6/Bi3.84W0.16O6.24 composites with enhanced photocatalytic performance

“…1, compared with the pattern of bulk WS 2 , the exfoliated few-layered WS 2 only possesses a broad and weak (0 0 2) diffraction peak, which is attributed to the destruction of van der Waals interactions between adjacent nanosheets [5,[43][44][45]. And the BET results show that the surface area of WS 2 became twice as much after exfoliation.…”