Facile Bottom-up Preparation of WS2-Based Water-Soluble Quantum Dots as Luminescent Probes for Hydrogen Peroxide and Glucose

Abstract

Photoluminescent zero-dimensional (0D) quantum dots (QDs) derived from transition metal dichalcogenides, particularly molybdenum disulfide, are presently in the spotlight for their advantageous characteristics for optoelectronics, imaging, and sensors. Nevertheless, up to now, little work has been done to synthesize and explore photoluminescent 0D WS 2 QDs, especially by a bottom-up strategy without using usual toxic organic solvents. In this work, we report a facile bottom-up strategy to synthesize high-quality water-soluble tungsten disulfide (WS 2 ) QDs through hydrothermal reaction by using sodium tungstate dihydrate and l -cysteine as W and S sources. Besides, hybrid carbon quantum dots/WS 2 QDs were further prepared based on this method. Physicochemical and structural analysis of QD hybrid indicated that the graphitic carbon quantum dots with diameters about 5 nm were held onto WS 2 QDs via electrostatic attraction forces. The resultant QDs show good water solubility and stable photoluminescence (PL). The excitation-dependent PL can be attributed to the polydispersity of the synthesized QDs. We found that the PL was stable under continuous irradiation of UV light but can be quenched in the presence of hydrogen peroxide (H 2 O 2 ). The obtained WS 2 -based QDs were thus adopted as an electrodeless luminescent probe for H 2 O 2 and for enzymatic sensing of glucose. The hybrid QDs were shown to have a more sensitive LOD in the case of glucose sensing. The Raman study implied that H 2 O 2 causes the partial oxidation of QDs, which may lead to oxidation-induced quenching. Overall, the presented strategy provides a general guideline for facile and low-cost synthesis of other water-soluble layered material QDs and relevant hybrids in large quantity. These WS 2 -based high-quality water-soluble QDs should be promising for a wide range of applications in optoelectronics, environmental monitoring, medical imaging, and photocatalysis. Electronic supplementary material The online version of this article (10.1186/s11671-019-3109-5) contains supplementary material, which is available to authorized users.

2D CTAB-MoSe2 Nanosheets and 0D MoSe2 Quantum Dots: Facile Top-Down Preparations and Their Peroxidase-Like Catalytic Activity for Colorimetric Detection of Hydrogen Peroxide

“…The prominent band is centered at around 275 nm, which is ascribed to the intrinsic excitonic absorption of the QDs [ 49 , 50 ]. Such a significant blue-shift of the excitonic features directly reflects the dominating quantum confinement effect and is in accordance with previous studies on other TMD QDs [ 32 , 51 ]. Furthermore, there exists another mild absorption band at longer wavelengths.…”

“…It is observed that when the excitation wavelength was increased from 290 to 400 nm, the PL peak position monotonically increased from 390 to 470 nm. Similar excitation-dependent PL behavior has been reported in a few TMD QD reports [ 32 ]. In a strong quantum confinement regime, photons with higher energies resonantly excites smaller QDs with wider band gaps, pushing the emission peak to shorter wavelengths.…”

“…For instance, TMD in quantum dot (QD) form deserves more investigation because their pronounced quantum confinement effects (QCE) and edge effects further aid applications in catalysts and sensing [ 29 , 30 ]. Significant enhancement in photoluminescence (PL) quantum efficiency by QCE is favorable to develop a sensor by optical means [ 31 , 32 ]. Moreover, a few optical properties in the strong coupling regime for semiconductor QDs and nanostructures could be implemented to strengthen the functionality of biosensors [ 33 , 34 , 35 ].…”

Recent Developments in Synthesis and Photocatalytic Applications of Carbon Dots

“…CDs/MoS 2 exhibited good catalytic activity for the hydrogen evolution reaction with high cathodic current density and a positive onset over-potential of~0.109 V. Surprisingly, even better performance was observed when the CD/MoS 2 catalyst was exposed to visible light for 30 min. Recently, hybrid CDs/tungsten disulfide quantum dots (CDs/WS 2 QDs) have been prepared from sodium tungstate dihydrate and l-cysteine by a bottom-up hydrothermal method and were used as a luminescent probe for the detection of H 2 O 2 and the enzymatic sensing of glucose [70].…”

Advancements in 2D Materials Based Biosensors for Oxidative Stress Biomarkers

“…The presence of hydrogen peroxide resulted in the quenching of WS 2 QDs fluorescence, proportional to the analyte concentration. 194 The quenched fluorescence of Rhodamine-B by sulfur doped graphene oxide was used as the sensing signal for the detection of hydrogen peroxide. The limit of detection for this system was as low as 100 pM.…”