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Tungsten disulfide saturable absorber for passively Q-Switched YVO4/Nd:YVO4/YVO4 laser at 1342.2 nm
摘要： By using both tungsten disul?de saturable absorber (WS2-SA) and YVO4/Nd:YVO4(0.3 at.%)/YVO4 crystal, a passively Q-switched laser centered at 1342.2 nm is ?rst reported. Stable Q-switched pulses can be obtained. At the pump power of 12 W, a shortest pulse width of 550 ns and a pulse repetition rate of 97 kHz can be observed by a digital oscilloscope, corresponding to maximum pulse energy of 5.55 μJ and pulse peak power of 10.1 W. The results promote the promising applications of WS2-SA in all-solid-state laser at 1.3 μm.
关键词： WS2 saturable absorber,Diode-pumped lasers,Q-switched lasers,1342.2 nm laser
更新于2025-11-28 14:23:57
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Investigation of Surface Plasmon Resonance (SPR) in MoS2- and WS2-Protected Titanium Side-Polished Optical Fiber as a Humidity Sensor
摘要： In this paper, we report the effects of a side-polished fiber (SPF) coated with titanium (Ti) films in different thicknesses, namely 5 nm, 13 nm, and 36 nm, protected by a thin layer of transition metal dichalcogenides (TMDCs) such as molybdenum disulfide (MoS2) and tungsten disulfide (WS2), which provide ultra-sensitive sensor-based surface plasmon resonance (SPR) covering from the visible to mid-infrared region. The SPF deposited with Ti exhibits strong evanescent field interaction with the MoS2 and WS2, and good optical absorption, hence resulting in high-sensitivity performance. Incremental increases in the thickness of the Ti layer contribute to the enhancement of the intensity of transmission with redshift and broad spectra. The findings show that the optimum thickness of Ti with 36 nm combined with MoS2 causes weak redshifts of the longitudinal localized surface plasmon resonance (LSPR) mode, while the same thickness of Ti with WS2 causes large blueshifts. The redshifts are possibly due to a reduced plasmon-coupling effect with the excitonic region of MoS2. The observed blueshifts of the LSPR peak position are possibly due to surface modification between WS2 and Ti. Changing the relative humidity from 58% to 88% only elicited a response in Ti/MoS2. Thus, MoS2 shows more sensitivity on 36-nm thickness of Ti compared with WS2. Therefore, the proposed fiber-optic sensor with integration of 2D materials is capable of measuring humidity in any environment.
关键词： tungsten disulfide (WS2),side-polished fiber (SPF),molybdenum disulfide (MoS2)
更新于2025-11-28 14:23:57
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Architectural Design of Photodetector Based on 2D (MoS <sub/>2</sub> ?Nanosheets)/1D (WS <sub/>2</sub> ?Nanorods) Heterostructure Synthesized by Facile Hydrothermal Method
摘要： Hydrothermal technique is utilized to synthesize 2D/1D heterostructure based on MoS2 (nanosheets)/WS2 (nanorods) for photodetector application. The sensor was fabricated by drop cast technique. X-Ray Diffraction (XRD), Fourier Transform Infra-red (FTIR) Spectroscopy, Field-Emission Scanning Electron Microscopy (FESEM), UV-Visible (Uv-Vis), Raman and X-Ray Photoelectron spectroscopy (XPS) were performed to characterize the synthesized sample. The optical sensor based on heterostructure was studied as a function of laser wavelength (λex): 635 nm (red), 785 nm (infra-red) and 1064 nm (near infra-red) and power of illuminated laser sources. The device exhibits photoresponsivity in a broadband range from the visible to the near-infrared (600–1065 nm, yield a photoresponsivity (Rp) = 15 μA/W and high speci?c detectivity (D?) = 24 × 106 jones at λex = 785 nm). The photoresponsive characteristics of MoS2/WS2 heterostructure hold the principle of simple power law.
关键词： MoS2 nanosheets,photodetector,hydrothermal method,WS2 nanorods,2D/1D heterostructure
更新于2025-11-21 11:01:37
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One-pot bottom-up fabrication of biocompatible PEGylated WS2 nanoparticles for CT-guided photothermal therapy of tumors in?vivo
摘要： Background: Tungsten disulfide (WS2), which enjoyed a good potential to be a promising clinical theranostic agent for cancer treatment, is still subject to the tedious synthesis procedure. Methods: Here, we reported a one-pot 'bottom-up' hydrothermal strategy for the fabrication of PEGylated WS2 nanoparticles (NPs). The WS2-PEG nanoparticles were characterized systematically. The CT imaging and photothermal therapy against tumor as well as biosafety in vitro and in vivo were also investigated. Results: The obtained WS2-PEG NPs enjoyed obvious merits of good solubility and favorable photothermal performance. WS2-PEG NPs exhibited desirable photothermal ablation ability against cancer cells and cancer cell-bearing mice in vitro and in vivo. MTT assay and histological analysis demonstrated the low cytotoxicity and biotoxicity of WS2-PEG NPs, providing a valid biosafety guarantee for the coming biomedical applications. In addition, thanks to the obvious X-ray attenuation of W atom, the WS2-PEG NPs can also be served as a favorable contrast agent for CT imaging of tumors. Conclusion: WS2-PEG NPs has enjoyed a good potential to be a promising clinical CT-guided photothermal therapeutic agent against cancers.
关键词： Photothermal therapy,Computed tomography,WS2,Tumor,Nanoparticles
更新于2025-11-14 17:03:37
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Percolation Effects in Electrolytically-Gated WS <sub/>2</sub> /Graphene Nano:Nano Composites
摘要： Mixed networks of conducting and non-conducting nanoparticles show promise in a range of applications where fast charge transport is important. While the dependence of network conductivity on the conductive mass fraction (Mf) is well understood, little is known about the Mf-dependence of mobility and carrier density. This is particularly important as the addition of graphene might lead to increases in the mobility of semiconducting nanosheet-network transistors. Here, we use electrolytic gating to investigate the transport properties of spray-coated composite networks of graphene and WS2 nanosheets. As the graphene Mf is increased, we find both conductivity and carrier density to increase in line with percolation theory with percolation thresholds (~8 vol%) and exponents (~2.5) consistent with previous reporting. Perhaps surprisingly, we find the mobility increases modestly from ~0.1 cm2/Vs (for a WS2 network) to ~0.3 cm2/Vs (for a graphene network) which we attribute to the similarity between WS2-WS2 and graphene-graphene junction resistances. In addition, we find both the transistor on- and off-currents to scale with Mf according to percolation theory, changing sharply at the percolation threshold. Through fitting, we show that only the current in the WS2 network changes significantly upon gating. As a result, the on-off ratio falls sharply at the percolation threshold from ~104 to ~2 at higher Mf. Reflecting on these results, we conclude that the addition of graphene to a semiconducting network is not a viable strategy to improve transistor performance as it reduces the on:off ratio far more than it improves the mobility.
关键词： graphene,ionic liquid,thin film transistor,WS2,carrier density,composite,mobility,Printed electronics
更新于2025-10-22 19:40:53
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Rectify Effect of Pedot:PSS/WS <sub/>2</sub> Heterostructure
摘要： Recently, devices based on organic and two-dimensional (2D) materials have been recognized as the easiest way to fabricate hybrid 2D van der Waals (vdW) heterojunction devices for electronic and optoelectronic applications. Depositing organic materials on 2D materials is typically demonstrated by thermal evaporation using high voltage and vacuum systems. In this paper, a simple way to fabricate organic/n-2D heterostructures, where Pedot:PSS is chosen to be the organic material due to its high conductivity, excellent film forming ability and good stability, while WS2 is selected as the n-2D material due to its well-known properties has been presented. By systematically studying the gate dependent and temperature-dependent I–V characteristics of the Pedot:PSS/WS2 heterojunctions, it is demonstrated that the device shows a diode-like behavior with rectification ratio (RF) of (cid:1)5 and a turn on voltage of (cid:1)2 V at room temperature (RT). Furthermore, the rectification ratio of the junction reaches up to 103 using a back-gate bias voltage (Vgs) of 20 V together with drain–source voltage (Vds) ranging from (cid:3)4 to 4 V. On the basis of the results, it is demonstrated that this simple technique of fabricating organic/2D vdW heterojunctions can extend to other organics and 2D materials.
关键词： 2-D heterjunction,Pedot:PSS,WS2
更新于2025-09-23 15:23:52
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Full spectrum responsive In2.77S4/WS2 p-n heterojunction as an efficient photocatalyst for Cr(VI) reduction and tetracycline oxidation
摘要： In the present work, wrinkled n-type WS2 nanosheets were synthesized and then used to construct the In2.77S4/WS2 p-n heterojunction photocatalyst. Experimental results reveal that the as-prepared hybrids present excellent photocatalytic activity for Cr(VI) reduction and tetracycline oxidation under visible and infrared light irritation. The photocatalytic efficiency of the as-prepared catalysts is found to increase initially followed by the decrease with the more weight content of WS2. When WS2 is up to 4 wt%, the as-prepared photocatalysts exhibit the highest photocatalytic activity, and are capable of reducing 99.1 % of Cr(VI) in 60 min and oxidizing 87.5 % of tetracycline in 20 min, much higher than 86.6 and 40.0 % of pure In2.77S4, respectively. This enhanced photocatalytic activity is attributed to the construction of In2.77S4/WS2 p-n heterojunction between p-In2.77S4 and n-WS2. The detailed clarification of photocatalytic mechanism is also elaborated in the paper.
关键词： In2.77S4,photocatalysis,heterojunction,WS2
更新于2025-09-23 15:23:52
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Edge/Defect-rich, Metallic, and Oxygen-heteroatom-doped WS2 Superstructure with Superior Electrocatalytic Performance for Green Solar Energy Conversion
摘要： Two-dimensional tungsten sulfide is widely applied in electrocatalysis field. However, WS2 possesses catalytic active sites located at the layer edge and an inert surface for catalysis. Therefore, increasing the exposure of active sites at the edge and effectively activating the inert sites on the surface is important challenges. Here, we synthesize edge/defect-rich and oxygen-heteroatom-doped WS2 (ED-O-WS2) superstructure. The power-conversion efficiency (PCE) of dye-sensitized solar cells (DSCs) based on ED-O-WS2 counter electrode reach 10.36% (under 1 Sun, AM 1.5, 100 mW cm?2) and 11.19% (under 40 mW cm?2). These values are, to our knowledge, the highest reported efficiency for DSCs based on Pt-free counter electrodes in I3-/I- electrolytes. Analysis of micro-nano structure and electrocatalytic mechanism indicate that ED-O-WS2 exhibit metallic properties in the electrolyte, and that rich edge/defect and oxygen doping in ED-O-WS2 play an important role in improving the catalytic activity of WS2. Moreover, ED-O-WS2 displays better catalytic reversibility for I3-/I- electrolytes than that of noble metal Pt.
关键词： WS2,green solar energy conversion,dye-sensitized solar cells,counter electrode
更新于2025-09-23 15:23:52
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Superior photocatalytic activity of tungsten disulfide nanostructures: role of morphology and defects
摘要： Tungsten disulphide (WS2) nanostructures, WS2 nanosheets (WNS) and WS2 nanorods (WNR), were synthesized by varying the surfactant, N-cetyl-N,N,N-trimethyl ammonium bromide (CTAB), concentration using facile hydrothermal technique. Samples were characterized by high-resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM) for morphology, X-ray diffraction (XRD) to confirm their phase and crystal structure, photoluminescence (PL) and Raman studies for the determination of defect density, Tauc plot for the determination of band gap, Fourier transform infra red (FTIR) spectroscopy for functional groups and bonds, and Brunauer–Emmett–Teller (BET) isotherms for the determination of pore size and surface area. A comparative study using WS2 nanostructures (WNS and WNR) was conducted to observe the photocatalytic degradation efficiency (?) and degradation kinetics on methylene blue (MB) and 4-chlorophenol (4-CP). The superior photocatalytic performance of WNS over WNR is attributed to enhanced pore size and reduced defect density. High-performance liquid chromatography was carried out for the determination of intermediate products during photocatalytic degradation.
关键词： Raman,High-performance liquid chromatography,WS2 nanostructures,Photoluminescence,Photocatalysis
更新于2025-09-23 15:23:52
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Polarized THz Emission from In-Plane Dipoles in Monolayer Tungsten Disulfide by Linear and Circular Optical Rectification
摘要： Recent advances in the development of polarized terahertz (THz) emission from nanomaterials have not only opened up a new “TeraNano” interdiscipline but also provided a new tool for nonlinear optical process research. Herein, THz radiation mechanism of monolayer tungsten disulfide (WS2) is first investigated by both linear and circular polarization laser excitations at room temperature. The results reveal that polarized THz emission is dominated by the optical rectification based on in-plane nonlinear dipoles, which is totally different from that of bulk WS2. The mechanism is verified by the azimuthal angle and pump polarization angle dependence of THz emission in both experiment and theory. Furthermore, controllably elliptically polarized THz emission is observed with the maximum ellipticity of ≈0.52 based on nonresonant nonlinear process under the circularly polarized excitation. A clear understanding of THz radiation mechanism of 2D materials will facilitate further design, optimization, and polarization control of integrable 2D THz optoelectronics.
关键词： THz radiation,monolayer WS2,in-plane nonlinear dipoles,optical rectification,elliptically polarized THz emission
更新于2025-09-23 15:23:52