- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Quantitative Understanding of the Ultra-Sensitive and Selective Detection of Dopamine using Graphene Oxide/WS2 Quantum Dot Hybrid
摘要： Herein, we report on the ultra-high sensitive and selective detection of dopamine (DA) at pico-molar level by a low cost sensing platform based on graphene oxide (GO) sheets anchored with tungsten disulfide quantum dots (WS2 QDs). The liquid phase exfoliated WS2 QDs are mostly bilayer type with an average particle size ~2.0 ± 0.3 nm, while the GO sheets are of few-layer thickness. The WS2 QDs are highly luminescent with photoluminescence (PL) quantum yield of ~15% and they exhibit excitation wavelength dependent spectral shift in PL due to the high degree of edge/defect states. In presence of GO, the PL intensity of WS2 QDs partially quenches due to van der Waals interaction and excited-state charge transfer from WS2 to GO. However, in the presence of DA, drastic quenching of PL occurs for WS2/GO hybrid and this enables selective detection of DA as low as 10 pM, which is the lowest among the reported values. We present a new model to quantitatively explain the GO mediated efficient charge transfer and unusual quenching of PL as a function of the DA concentration. Finally, the WS2/GO based sensor is utilized for the detection of DA in the river water and blood serum with a satisfactory recovery, which establishes its practical utility as an efficient environmental/biochemical sensor.
关键词： Fluorescence Quenching,Dopamine,Biosensor,Graphene Oxide,WS2 Quantum Dots
更新于2025-09-23 15:21:01
-
Highly Stable and Flexible Memristive Devices Based on Polyvinylpyrrolidone: WS2 Quantum Dots
摘要： Tungsten disulfide (WS2) quantum dots (QDs) embedded in polyvinylpyrrolidone (PVP) based flexible memristive devices were prepared, and those devices exhibited typical bistable electrical switching and remarkable nonvolatile memristive behaviors. Maximum electricity on/off ratio obtained from the current–voltage (I-V) curves of the device is close to 104. the set voltage of the device is +0.7 V, which effectively reduced the energy consumption. The retention times extracted from data for the devices were as large as 1 × 104 s, which points to these devices having nonvolatile characteristics. Moreover, the highly flexible characteristics of the devices were demonstrated by bending the devices. The carrier transport mechanisms were explained by fitting the I-V curves, and possible operating mechanisms of the devices can be described based on the electron trapping and detrapping processes. WS2 QDs uniformly dispersed in pure transparent N, N-Dimethylformamide (DMF) were obtained by using ultrasonication and a hydrothermal process in this work.
关键词： memristive devices,nonvolatile memory,polyvinylpyrrolidone,WS2 quantum dots,flexible electronics
更新于2025-09-19 17:13:59
-
Understanding the excitation wavelength dependent spectral shift and large exciton binding energy of tungsten disulfide quantum dots and its interaction with single-walled carbon nanotubes
摘要： Herein, we investigate the origin of excitation wavelength dependent spectral features and high fluorescence quantum yield in fluorescent 2D tungsten disulfide (WS2) quantum dots (QDs) of average size 2.4 nm. The as-prepared WS2 QDs possess high optical bandgap and reasonably high fluorescence quantum yield ~15.4% in the green region without any functionalization. The broad photoluminescence (PL) spectrum consists of multiple peaks owing to emissions from excitonic transitions and surface defect-related transitions. The excitation wavelength-dependent spectral redshift and narrowing of line shape in the PL peak are analyzed carefully, and it is attributed to the selective excitation/recombination of carriers from different energy levels. The temperature-dependent PL analysis yields an exciton binding energy of ~301 meV in the QDs. Furthermore, we study the interaction between fluorescent WS2 QDs and single-walled carbon nanotubes (SWCNTs) and explore the mechanism of systematic quenching of PL of QDs by SWCNTs. The nature of the Stern–Volmer plot is found to be linear, and the time-resolved fluorescence measurements reveal that the quenching follows primarily the static behavior. Our study further reveals that defect sites in SWCNTs primarily act as the binding sites for WS2 QDs and form non-fluorescent complexes for effective quenching of the PL. The strong interaction between the WS2 QDs and the SWCNTs is evidenced from the spectral shift in the X-ray photoelectron spectroscopy and Raman peaks. Our study reveals the origin of excitation wavelength dependent PL emission from WS2 QDs and the nature of the interaction between WS2 QDs and SWCNTs, which are important for their applications in biomedical imaging and sensing, such as surface-enhanced Raman scattering, etc.
关键词： WS2 quantum dots,Fluorescence quenching,Defects,Carbon nanotubes,Exciton binding energy
更新于2025-09-16 10:30:52
-
WS2 quantum dots seeding in Bi2S3 nanotubes: A novel Vis-NIR light sensitive photocatalyst with low-resistance junction interface for CO2 reduction
摘要： Efficient photocatalysts sensitive to visible and near infrared lights have attracted increased concerns owing to the high utilization efficiency of solar energy. Herein, WS2 quantum dots (WS2 QDs) doped Bi2S3 nanotubes with smooth surface were constructed by seed-mediated strategy with WS2 QDs as seeds, which show sensitive response to Vis-NIR lights. In WS2@Bi2S3 structure, exposed S atoms in WS2 QDs combined Bi3+ ions to form Bi-S bonds, and enabled the S-sharing between WS2 and Bi2S3 unit cells. The perfect junction interface between WS2 and Bi2S3 is straight and smooth without any disordered atoms, endowing low resistance for fast electron transfer on the interface and efficient separation of electron-hole pairs. Compared with pristine Bi2S3 nanotubes, the WS2@Bi2S3 nanotubes display enhanced photocatalytic activity in CO2 reduction, with 38.2 μmol g-1 of methanol and 27.8 μmol g-1 of ethanol achieved at optimal WS2 loading content (4 wt%) under Vis-NIR light irradiation for 4 h. It is proposed that the low-resistance interface between WS2@Bi2S3 heterojunction and the regulated electron pathway along Bi2S3 nanotubes account for the high photocatalytic activity, which enables WS2@Bi2S3 a promising and unique photocatalyst, and indicates a new direction for light harvest.
关键词： WS2 quantum dots,Bi2S3 nanotube,photocatalytic reduction of CO2,seed-mediated,heterojunction interface
更新于2025-09-12 10:27:22