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Triplea??wavelength Qa??switched ytterbiuma??doped fiber laser based on tungsten oxide as saturable absorber
摘要： In this article, a multiwavelength Q-switched ytterbium-doped fiber laser using tungsten oxide nanoparticles (WO3 NPs) as a saturable absorber (SA) is reported for the first time. The SA was prepared by depositing micron-sized layers of WO3 NPs suspension onto the surface of the fiber tip via direct deposition process. After embedding the SA into an ytterbium-doped fiber laser cavity, self-starting Q-switched performance was realized at a bleaching threshold of 179 mW having a minimum pulse width of 2.92 μs and maximum pulse energy of 9.26 nJ with variable repetition rates from 14.8 to 71.3 kHz. By boosting the pump power and proper adjustment of the polarization controller, steady dual- and triple-wavelength operations were obtained at pump powers of 210 and 275 mW, respectively. The obtained results confirm the practical use of WO3 as an effective nonlinear modulator for multiwavelength and pulsed fiber lasers near 1 μm wavelength band.
关键词： multiwavelength,passive saturable absorber,YDFL,Q-switching,tungsten oxide nanoparticles
更新于2025-09-23 15:19:57
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Niobium incorporated WO3 nanotriangles: Band edge insights and improved photoelectrochemical water splitting activity
摘要： In this work, a facile hydrothermal method is proposed to fabricate Nb-doped WO3 nanotriangle thin films, and their band edge properties and photoelectrochemical water splitting activity were explored. The process of doping and thin film formation was simultaneously achieved in a single step hydrothermal condensation of peroxopolytungstic acid solution containing Nb precursor. The crystallographic study reveals that doping of Nb into WO3 lattice obstructs the reconstructive transformation of orthorhombic WO3·0.33H2O during annealing consequently producing hexagonal phase instead of the monoclinic phase. The insertion of Nb causes the increase in band gap and induces oxygen vacancies in WO3. Uniform distribution of Nb in WO3 was observed containing majorly Nb5+ valence and a small amount of Nb4+ state. PEC characterization showed the increase in photocurrent, (at AM 1.5G illumination) incident photon to current and photoconversion efficiency values of WO3 upon Nb doping. Band edge analysis revealed that both conduction and valence band edge of WO3 show downward shift towards higher potential vs. RHE whereas the Fermi level show upward shift as a result of Nb doping.
关键词： Band edge,Niobium,Reconstructive transformation,Tungsten oxide,Photoelectrochemical water splitting
更新于2025-09-19 17:15:36
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Facile Synthesis of Fluorescent Tungsten Oxide Quantum Dots for Telomerase Detection Based on the Inner Filter Effect
摘要： The traditional detection of telomerase activity is mainly based on the polymerase chain reaction (PCR), which has the disadvantages of being time-consuming and susceptible to interference, and we here propose a facile method to fabricate fluorescent tungsten oxide quantum dots (WOx QDs) and employ them for telomerase activity sensing. It is found that the fluorescence of WOx QDs can be significantly quenched by hemin based on the inner filter effect (IFE). However, in the presence of telomerase, the primer-DNA can be extended to generate repeating unit of TTAGGG to form G-quadruplex, and thus hemin can be encapsulated to reduce its absorbance, resulting in decreased IFE and efficient fluorescence recovery of WOx QDs. Based on the fluorescence changes of IFE between hemin and WOx QDs, the telomerase activity with the range of 50-30000 HeLa cells can be detected and the lowest detection amount can reach 17 cells. The method exhibits good versatility that can be also applied to the telomerase detection from A549 and L929 cells. In addition, because of the good biocompatibility of the sensor, it can be used for real-time monitoring of telomerase activity in living cells, showing great potential in tumor diagnosis and inhibitor drug screening.
关键词： inner filter effect,G-quadruplex,hemin,telomerase activity detection,fluorescent tungsten oxide quantum dots
更新于2025-09-19 17:13:59
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Plasmonic Molybdenum Tungsten Oxide Hybrid with Surface-Enhanced Raman Scattering Comparable to that of Noble Metals
摘要： The Surface-enhanced Raman Scattering (SERS) research is in full swing owing to its high sensitivity and high selectivity, however, the substrate with a superexcellent performance for SERS is largely confined to noble metals (Au and Ag, etc.). Although the SERS active substrate has been extended to semiconductor and transition metal, it is frustrating that their sensitivity is insufficient for widespread practical application. Here we report the plasmonic molybdenum tungsten oxide hybrid (MWO) nanomaterials (NMs) which can be used as a high-performance substrate with noble metal-comparable SERS. MWO NMs can achieve the trace detection of rhodamine 6G (R6G), basic fuchsin (BF), and oil red O (ORO). The detection limit concentration for R6G is 10-8 M with the maximum enhancement factor is up to 6.09×107. The superexcellent SERS performance was put down to the cooperative enhancement effect of electromagnetic enhancement mechanism (EM) and the charge transfer mechanism (CT). Moreover, in the proposed system, the EM and CT contribution was distinguished by employing the PVP, which serves as a barrier layer to prevent the CT process from MWO NMs to R6G. This remarkable MWO NMs can be obtained with a facile method and this research shows a new insight on the non-noble metal-based SERS substrate.
关键词： Molybdenum tungsten oxide hybrid,R6G,Noble metal-comparable,SERS,Plasmonic
更新于2025-09-19 17:13:59
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Effects of oxidation state on photovoltaic properties of reactively magnetron sputtered hole-selective WO<sub>x</sub> contacts in silicon heterojunction solar cells
摘要： The stoichiometry value x of WOx, or its oxidation state, is crucial for improving performances of the hole-selective contact heterojunction silicon solar cell. However, it is challenging to tune the films’ oxidation state using the well-known evaporation method. In this study, a simulation was performed to analyze the effect of x on short-circuit current (Jsc) loss, attributed to the hole-selective contact in the device. Compared to the thickness of WOx layer, x has a more important role in minimizing Jsc loss. Based on the simulation, the WOx/c-Si heterojunction solar cells having hole-selective WOx contacts with tuned x to vary its oxidation state were fabricated using reactive magnetron sputtering. The relationships of the open-circuit voltage (Voc) and Jsc with respect to x were similar. The experimentally determined Jsc increased from 34.7 to 36.6 mA/cm2 when x was increased from 2.72 to 2.77; this result is consistent with the simulation. Nevertheless, fill factor (FF) reduced with the increase of x, owing to the reduced conductivity of WOx. Both oxidation state and film conductivity must be as high as possible to simultaneously achieve high Voc, Jsc, and FF. The lowest x yielded a solar cell efficiency of 13.3%.
关键词： Current loss,Tungsten oxide,Hole-selective contact,Heterojunction solar cell
更新于2025-09-19 17:13:59
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Fabrication of dopamine enveloped WO3?x quantum dots as single-NIR laser activated photonic nanodrug for synergistic photothermal/photodynamic therapy against cancer
摘要： Tungsten oxide is a promising nanodrug in phototherapy via transforming light energy to reactive oxygen species and heat. Nevertheless, the phototherapeutic activity of the tungsten oxide nanomaterials is generally activated under 980 nm laser, which is close to the absorption of normal tissue, resulting in unfavorable heating effect on normal tissues. Therefore, the tungsten oxide nanomaterials which can be excited under 808 nm are highly required to avoid overheating and obtain deep tissue penetration of near-infrared (NIR) laser. Here, we successfully synthesized a novel dopamine enveloped tungsten oxide nanodots (WO3?x/Dpa-Mel NPs) via facile one-step solvothermal route, using dopamine as the template and reductant in triethylene glycol solvent. Under the 808 nm laser irradiation, the as-obtained WO3?x/Dpa-Mel NPs exhibit excellent photodynamic activity and stability. Meanwhile, the WO3?x/Dpa-Mel NPs also possess high photothermal conversion property. Thus, the photothermal therapy (PTT) and photodynamic therapy (PDT) can be triggered simultaneously under single 808 nm laser irradiation. Additionally, the inherited good biocompatibility and dispersity in aqueous solution from dopamine hydrochloride (Dpa-Mel) also make the WO3?x/Dpa-Mel NPs more suitable for in vivo application. The as-obtained WO3?x/Dpa-Mel NPs exhibit an excellent synergistic phototherapy effect on solid tumor ablation in vivo without damaging healthy tissues under single 808 nm NIR light irradiation, indicating WO3?x/Dpa-Mel NPs can serve as a multifunctional therapeutic nanoplatform to realize the synergistic cancer therapy.
关键词： Photothermal therapy,Combined cancer therapy,Tungsten oxide,Photodynamic therapy
更新于2025-09-19 17:13:59
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Hyperthermia Induced by Near-Infrared Laser-Irradiated CsWO3 Nanoparticles Disintegrates Preformed Lysozyme Amyloid Fibrils
摘要： This research study attempts to prove the concept of the applicability of hyperthermia to treating the lysozyme amyloid fibrils (LAF)’s self-assembled fibrillary aggregates by a feedback-modulated temperature controller ranging from 26 °C to 80 °C, and separately, by near-infrared (NIR) laser-irradiated cesium tungstate (CsWO3) nanoparticle (NPs). The dependence of the final morphology of the amyloidal assembly on external heating and the photothermal effect of the NPs on treating the fibrillary assembly were investigated and analyzed. Experimentally, atomic force microscopy (AFM), optical stereoscopy, and scanning electron microscopy (SEM) were used primarily to ensure mutual interaction between LAF and NPs, optically elucidate the surface contour and final fibrillary assembly upon the influence of thermal treatment, and further reveal fine-details of the optical samples. Finally, conclusive remarks are drawn that the fibrillary structures doped with the NPs exhibit an increasing degree of unique orthogonality. As the temperature rises, utter deformation of the dendritic structures of fibrillary assemblies at 70 °C was found, and NIR laser-irradiated CsWO3 NPs have been demonstrated to be useful in topically destructing pre-assembled LAFs, which may be conducive to the future development of neurodegenerative therapeutic techniques.
关键词： neurodegenerative diseases,self-assembled nanocomposite,lysozyme amyloid fibrils,hyperthermia,cesium tungsten oxide nanoparticles
更新于2025-09-16 10:30:52
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Improving the charge balance and performance of CdSe/ZnS quantum-dot light-emitting diodes with a sputtered zinc-tin-oxide electron-transport layer and a thermally evaporated tungsten-oxide charge-restricting layer
摘要： The charge carrier balance and performance of CdSe/ZnS quantum-dot light-emitting diodes (QD-LEDs) with a vacuum-deposited electron-transport layer (ETL) and carrier-restricting layer (CRL) were successfully improved. Optimizing the fabrication process of the reactively sputtered zinc-tin-oxide (ZTO) ETL and adopting a thermally evaporated tungsten-oxide (WOx) CRL improved the electron-hole balance, thus leading to QD-LEDs with improved performance. Impedance spectroscopy analysis was successfully exploited in investigating charge carrier injection into each layer of the QD-LED and electron-hole recombination behaviors. The QD-LED with optimized ZTO ETL and without WOx CRL exhibited 2600 cd m?2 luminance and 3.2 cd A?1 current efficiency, and the QD-LED with both optimized ZTO ETL and a WOx CRL exhibited 3900 cd m?2 luminance and 5.1 cd A?1 current efficiency. These results imply a practical method for improving the electron-hole balance and performance of QD-LEDs, and provide a reliable technique for analyzing the carrier behavior of QD-LEDs.
关键词： CdSe/ZnS quantum-dot,light-emitting diodes,tungsten-oxide,charge balance,zinc-tin-oxide,impedance spectroscopy
更新于2025-09-11 14:15:04
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Analog Resistive Switching and Synaptic Functions in WOx/TaOx Bilayer Through Redox Induced Trap-Controlled Conduction
摘要： In this study, the abrupt set/reset behavior of the Ta/TaOx/Pt resistive switching (RS) device is reformed to a gradual mode by inserting a WOx layer between the TaOx active layer and the Ta top electrode. With the WOx acting as a redox layer to exchange oxygen vacancies at the interface, the defect states in TaOx are regulated via applying bias and the analog resistive switching is rationalized by trap-controlled space-charge-limited conduction mechanism. Continual change in device resistance can be achieved by repeated voltage sweeping. Based on the analog RS behavior, the potentiation and depression behaviors with excellent linearity are also demonstrated by identical voltage pulse stimulation and the operating current is maintained at less than 10?6 A. Furthermore, essential synaptic functions, such as paired-pulse facilitation (PPF), long- and shot-term potentiation (LTP and STP), experience dependent plasticity (EDP) and learning-relearning are also demonstrated to mimic the biological synapses for the application of neuromorphic computing.
关键词： synaptic function,tungsten oxide,space-charge-limited conduction,Analog resistive switching,redox layer
更新于2025-09-11 14:15:04
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Hydrogen gas sensing properties of WO3 sputter-deposited thin films enhanced by on-top deposited?CuO nanoclusters
摘要： Magnetron-based gas aggregation cluster source (GAS) was used to prepare high-purity CuO (cupric oxide) nanoclusters on top of sputter-deposited thin film of tungsten trioxide (WO3). The material was assembled as a conductometric hydrogen gas sensor and its response was tested and evaluated. It is demonstrated that addition of CuO clusters noticeably enhances the sensitivity of the pure WO3 thin film. With an increasing amount of CuO clusters the sensitivity of CuO/WO3 system rises further. When CuO clusters form a sufficiently thick and compact layer, the resistance response is reversed. Based on the sensorial behavior, conventional and near-ambient pressure X-Ray photoemission spectroscopies, and resistivity measurements, we propose that the sensing mechanism is based on the formation of nano-sized p-n junctions in between p-type CuO and n-type WO3. The advantages of the GAS technique for preparing sensorial and/or catalytically active materials are emphasized.
关键词： Hydrogen gas sensor,Gas aggregation cluster source,Magnetron sputtering,Tungsten oxide,Nanocomposites,Cupric oxide
更新于2025-09-10 09:29:36