WS2 Nanosheets Research Articles

Influence of PEGylation on WS2 Nanosheets and Its Application in Photothermal Therapy.

Photothermal therapy (PTT) is an alternative cancer therapy with minimal side effects and higher efficiency and selectivity. In this study, WS2 nanosheets were developed by ultrasonic exfoliation with different ratios of polyethylene glycol (PEG), and their effects on physicochemical properties were studied. The utilization of PEG during sonication significantly influenced the size and thickness of the resulting WS2 nanosheet layers, which was confirmed through scanning electron microscopy, atomic force microscopy, and dynamic light scattering analyses. PEG functionalization also improved the dispersibility of WS2 in aqueous solution by making its surface hydrophilic, which resulted in better biocompatibility. The intrinsic near-infrared absorbance of the nanosheets positions them as valuable agents for PTT. The study further explores the efficacy of these nanosheets as photothermal agents in the ablation of MDAMB-231 breast cancer cells. Although the use of PEG to demonstrate exfoliation and biocompatibility for WS2 has been reported previously, the effect of PEGylation on various physicochemical properties has not been studied in-depth until now. This study paves the way for the use of highly versatile PEG across a range of 2D material systems.

Integrated wearable foam modified with WS2 nanosheets@MoS2 quantum dots for oral disease diagnosis and healthcare monitoring

To develop a sensitive point-of-care platform for screening hidden caries, periodontitis and functional dyskinesia is highly desirable. Breath analysis is considered as a promising method for non-invasive clinical diagnostics. When further combined with monitoring the movement disorders of maxillofacial region, the accuracy of disease diagnosis can be greatly improved. However, the design and investigation of integrated sensing platform for multiple stimuli are currently limited. In this study, a multifunctional heterostructure combined p-type WS2 nanosheets with n-type MoS2 quantum dots (WS2/MoS2 heterostructure) is designed for realizing multi-parameters sensing via assistance of different substrate. The gas sensor based on an optimized WS2/MoS2 heterostructure (W:Mo = 300:1) exhibits an enhanced response (73.1 % to 1 ppm) and the limit of detection is 10 ppb at room temperature (25 °C) under UV assistance. The improvements in gas sensing performance can be attributed to the synergistic effect of heterostructure, sensitization of QDs and UV photoactivation. The electromechanical sensor achieved by modified WS2/MoS2 heterostructure on conductive TPU foam exhibits excellent linearity, as well as a wide sensing range of 10 %–160 % strain and 5–250 kPa pressure, respectively. In addition, it is effective in perceiving subtle or large oral and maxillofacial movements. Finally, a multifunctional wearable platform is successfully employed to differentiate the respiratory biomarkers of healthy individuals from simulated exhaled breath in patients with caries and periodontitis, and to discriminate bite force of incisors and molars in diverse populations. This wearable device offers a promising, practical, and sustainable strategy for mobile treatment platforms and personalized healthcare.

One-pot synthesis of Fe2O3/WS2 heterojunction for improved visible-light-driven photo-Fenton-like reaction

The Fe2O3/WS2 composite was synthesized using a one-pot solid-state reaction, resulting in highly dispersed Fe2O3 on two-dimensional (2D) WS2 nanosheets. The obtained composites outperformed pure WS2 and Fe2O3 in photo-Fenton-like (PFL) activity for the degradation of Rhodamine B under visible light, with the highest elimination efficiency of 95.61% after 70 mins of treatment. The Fe(III)/Fe(II) cycling reaction can be strengthened by the photogenerated electrons from WS2 to Fe2O3, which significantly increases the efficiency of H2O2 consumption and then enhances the PFL activity. This is due to the possibly promoting charge transfer over the hetero-interface of Fe2O3 and WS2, accelerating strong redox power, and elongating photo-induced charge carriers’ lifetime.

Casein-assisted exfoliation of tungsten disulfide nanosheets for biomedical applications

Our regular life can be more challenging by bone abnormalities. Bone tissue engineering is used for repairing, regenerating, or replacing bone tissue that has been injured or infected. It is effective in overcoming the drawbacks of conventional bone grafting methods like autograft and allograft by enhancing the effectiveness of bone regeneration. Recent discoveries have shown that the exfoliation of transition metal dichalcogenides (TMDs) with protein is in great demand for bone tissue engineering applications. WS2 nanosheets were developed using casein and subsequently characterized with different analytical techniques. Strong absorption peaks were observed in the UV–visible spectra at 520 nm and 630 nm. Alginate and alginate–casein WS2 microspheres were developed. Stereomicroscopic images of the microspheres are spherical in shape and have an average diameter of around 0.8 ± 0.2 mm. The alginate-casein WS2 microspheres show higher content of water absorption and retention properties than only alginate-containing microspheres. The apatite formation in the simulated bodily fluid solution was facilitated more effectively by the alginate-casein-WS2 microspheres. Additionally, alginate-casein-WS2 microspheres have a compressive strength is 58.01 ± 4 MPa. Finally, in vitro cell interaction studies reveals that both the microspheres are biocompatible with the C3H10T1/2 cells, and alginate-casein-WS2-based microspheres promote cell growth more significantly. Alginate-casein-WS2 microspheres promote alkaline phosphatase activity, and mineralization process. Additionally, alginate-casein-WS2-based microspheres exponentially enhance the genes for ALP, BMP-2, OCN, and Collage type-1. The produced alginate-casein-WS2 microspheres could be a suitable synthetic graft for a bone transplant replacement.

One-step hydrothermal synthesis of core-shell structural silicon carbide@WS2 with high efficiency for microwave absorption

The rapid development of communication technology has put new demands on high-efficiency microwave absorbing materials. In this study, silicon carbide particles are totally wrapped with two-dimensional WS2 through one-step hydrothermal method. Such core-shell structural SiC@WS2 composites show the minimum reflection loss of −50.52 dB with the thickness of 2.1 mm, and broadest absorbing bandwidth of less than −10 dB is 4.60 GHz with the thickness of 1.9 mm. The introduction of WS2 nanosheets enhance interfacial polarization and multiple scattering for composites. Besides, the special core-shell structure improves the surface anisotropy resulting in a better match of electromagnetic parameters. This work provides a facile and efficient synthesis process to enhance the absorbing abilities of powder materials.

Ultra-thin WS2 decorated Co-based Metal‒organic framework derived materials for synergistic electrocatalysis towards pH-Universal hydrogen evolution reaction

Rational designing of a WS2-based hybrid material is extremely important to resolve low-edge sites and poor conductivity of bare WS2, but it is still challenging to construct applicable structures. In this study, an electrocatalyst with ultra-thin WS2 nanosheets homogeneously decorated on Co–N-co-doped carbon hollow nanocages (WS2-3/Co–N–CN-750) is developed, which has favorable hydrogen evolution reaction (HER) activity and stability. The performance of WS2-3/Co–N–CN-750 is significantly improved due to the collective synergy of the specific micro-morphology, interfacial structure, and electronic property. The hybridization of WS2 and Co9S8 can optimize the electronic structure, reduce hydrogen adsorption energy, slash the decomposition barrier of H2O, and accelerate the electron transfer to WS2. Furthermore, the marginal sites of WS2 are significantly increased by optimizing the aggregation growth of WS2. Besides, the precipitation of appropriate Co particles and the Co-based metal-organic framework (Co-MOF) lay a solid foundation for the favorable conductivity of the hybrid material. However, samples after stability tests reveal that cobalt sulfide is corroded and transformed in a locally strong alkali condition. This study highlights the synergies of multicomponent hybridization and provides insights into the stability of congeneric materials.

Probe ultrasonication synthesis of Eu2O3-doped 2D WS2 nanosheets for highly selective and sensitive quantification of human catecholamines by fluorescent quenching and shifting

Tungsten disulfide (WS2) nanosheets have been intensively investigated in many fields due to their high crystallinity, outstanding electrochemical properties, and structural integrity. A cutting-edge bottom-up approach with the assistance of probe ultrasonication and annealing was used to synthesize 2D WS2 nanosheets. These nanosheets were modified by probe ultrasonication-assisted doping of Eu2O3 to obtain the reddish-orange color fluorescence with a 68.32% relative quantum yield. This as-synthesized material was used to develop a quenching and shifting associated turn-off turn-on combined type bio-sensor for the detection of human catecholamines. It showed a perfect and wide linear range of 50–800 µM for norepinephrine, epinephrine, and dopamine while the reported detection limits were 0.36 µM, 0.91 µM, and 0.15 µM, respectively. It showed a great recovery of 95% for the human urine sample analysis with spiked analytes. In addition, this could be used as a drug quality assurance option for neurotransmitter drugs.

Confined oxidation of 2D WS2 nanosheets forming WO3/WS2 nanocomposites for room temperature NO2 gas sensing application

In this article, we synthesized WO3/WS2 nanocomposites by facile hydrothermal synthesis followed by thermal annealing treatment and analysed its gas sensing properties. The thermal annealing process was carried out in different temperatures from 400 ℃ to 600 ℃ to form WO3/WS2 nanocomposite. During the thermal annealing process, the hydrothermally synthesized pure WS2 nanosheets undergo partial oxidation constructing WO3 on the surface developing active heterojunctions leading to increment in the sensing performance. The fabricated WO3/WS2 samples showed superior sensitivity and selectivity towards NO2 gas molecules. The pristine WS2 nanosheets showed a response of 26% towards 10 ppm of NO2 gas with a response and recovery time of 13 s /18 s, whereas WO3/WS2 nanocomposite prepared by annealing at 600 ℃ showed a maximum response of around 123% with a short response time of 11 s and recovery time of 163 s. The DFT calculations were performed to understand the gas sensing performance and interfacial charge transfer between the WO3/WS2 nanocomposite and gas molecules. Therefore, this study demonstrates that the indigenous heterojunctions contribute extensively to improving the gas detection capabilities of WO3/WS2 nanocomposites at room temperature.

Low-Dose Exposure of WS2 Nanosheets Induces Differential Apoptosis in Lung Epithelial Cells.

Escalating the production and application of tungsten disulfide (WS2) nanosheets inevitably increases environmental human exposure and warrants the necessity of studies to elucidate their biological impacts. Herein, we assessed the toxicity of WS2 nanosheets and focused on the impacts of low doses (≤10 μg/mL) on normal (BEAS-2B) and tumorigenic (A549) lung epithelial cells. The low doses, which approximate real-world exposures, were found to induce cell apoptosis, while doses ≥ 50 μg/mL cause necrosis. Focused studies on low-dose exposure to WS2 nanosheets revealed more details of the impacts on both cell lines, including reduction of cell metabolic activity, induction of lipid peroxidation in cell membranes, and uncoupling of mitochondrial oxidative phosphorylation that led to the loss of ATP production. These phenomena, along with the expression situations of a few key proteins involved in apoptosis, point toward the occurrence of mitochondria-dependent apoptotic signaling in exposed cells. Substantial differences in responses to WS2 exposure between normal and tumorigenic lung epithelial cells were noticed as well. Specifically, BEAS-2B cells experienced more adverse effects and took up more nanosheets than A549 cells. Our results highlight the importance of dose and cell model selection in the assessment of nanotoxicity. By using doses consistent with real-world exposures and comparing normal and diseased cells, we can gain knowledge to guide the development of safety precautions for mitigating the adverse impacts of nanomaterial exposure on human health.

Decoration of Pt/Pd bimetallic nanoparticles on Ru-implanted WS2 nanosheets for acetone sensing studies

Bimetallic decoration is a promising technique for enhancing the gas-sensing characteristics of resistive sensors. In this study, pristine WS2 nanosheets (NSs), Ru-implanted WS2 NSs, separate Pt and Pd nanoparticles (NPs) decorated on Ru-implanted WS2 NSs, and Pt/Pd bimetallic NPs decorated on Ru-implanted WS2 NSs sensors were prepared and utilized for acetone detection in self-heating operations at low applied voltages (1–5 V). The gas sensors were characterized by employing various techniques to explore their phases, morphologies, and chemical compositions. The Ru-implanted WS2 NSs sensor decorated with Pt/Pd bimetallic NPs exhibited good selectivity and fast dynamics toward acetone. Also, the optimized sensor displayed an acceptable response to acetone even in a high-humidity environment. The enhanced acetone sensing of the optimized gas sensor was related to the spillover and catalytic effects of the implanted Ru and Pt/Pd NPs on acetone, enhanced oxygen ionosorption with the formation of defects under implantation, and the formation of Schottky barriers between Pt/Pd and Ru-implanted WS2. We successfully demonstrated the potential of this novel sensing material for room-temperature acetone sensing.

(Invited) Ultrafast Charge Transfer Dynamics in WS2–Au Nanohybrid System Fabricated by Pulsed Laser Ablation in Liquid

Nanosheet semiconductor materials have attracted much attention in recent years due to their unique optical, electronic, and chemical properties for various applications such as photodetectors, light emitters, photocatalysts, and biosensors. We have fabricated tungsten disulfide (WS2) nanostructures by pulsed laser ablation in liquid. We applied nanosecond and femtosecond lasers and found the latter to be suitable for nanosheet fabrication [1]. Visible light response was enhanced by attaching gold nanoparticles (AuNPs) onto WS2 nanosheets [2]. The charge transfer dynamics in the WS2-Au nanohybrid system was characterized using femtosecond diffuse reflectance spectroscopy. The nanosheet structure was found to reduce the bulk carrier property. Furthermore, modification with AuNPs was found to enhance the formation of carriers trapped deeply in the WS2 nanosheets. These findings will be useful for the design of future metal-nanosheet semiconductor hybrid systems.Reference Pankaj Koinkar, Kohei Sasaki, Tetsuro Katayama and Akihiro Furube, International Journal of Modern Physics B, 35, 2140007 (2021)Tatsuki Kokufu, Daichi Nakayama, Tetsuro Katayama, Koinkar Pankaj, and Akihiro Furube, The 13th Asia-Pacific Conference on Near-Field Optics, OL30-A13 (2022)

Evaluation of lubrication potential of Ni3Al-WS2-Cu-doped hBN self-lubricating hybrid composites

The lubricating potential of WS2 and Cu-doped hBN nanosheets (Cu-hBN) as solid lubricants in Ni3Al-based composites has been evaluated by conducting wear tests from room temperature (RT) to 800 °C. The results indicate a decreasing trend of coefficient of friction with increasing temperature from RT to 800 °C with Ni3Al showing the highest wear rate as well as coefficient of friction (0.65–0.42) and Ni3Al-WS2-Cu-hBN (0.44–0.18) showing the lowest at all the temperatures except at RT, 200 and 400 °C, at which Ni3Al-WS2 has the lowest coefficient of friction. The improved performance of Ni3Al-WS2-Cu-hBN reflects a cooperative synergy between WS2 and Cu-hBN at temperatures beyond 400 °C, whereas the combination did not reveal any assistive action below 400 °C.

Cost-effective synthesis of highly-dispersed WS2 nanosheets assembled on tourmaline for improved photocatalytic activity

Tungsten disulfide (WS2) has attracted much attention in photocatalysis due to the excellent visible light harvesting and charge transfer kinetics, yet practical applications have been severely limited by the restacking property. In this work, a novel WS2/tourmaline composite was fabricated by coupling hydrothermal and calcination methods. The highly dispersed WS2 nanosheets homogeneously deposited on the tourmaline surface were revealed by electron microscopy, with sufficient exposure of the photocatalytic sites to enhance the migration efficiency of interfacial electrons. The armadillo-like WS2/tourmaline composite exhibited excellent photocatalytic activity for rhodamine B (RhB), with a degradation efficiency of 89.4 % after 150 min irradiation, while only 30.4 % was achieved by the pure WS2 microspheres. Electron paramagnetic resonance and density functional theory (DFT) calculations showed that the WS2/tourmaline composites with more sulfur vacancies preferred to produce sufficient reactive species for photocatalytic RhB degradation. In addition, photogenerated holes (h+) play a more important role in the degradation process of RhB than superoxide radicals (·O2–) and hydroxyl radicals (·OH), as confirmed by radical quenching experiments. This work presents a new option for the low-cost preparation of high-performance 2D materials via mineral assembly.

WS2 nanosheets modified via ZnO nanorods (2D/1D) nanocomposite: An efficient photocatalyst for the removal of Cr (VI), humic acid and textile dyes from wastewater

In present study, photocatalytic removal of (i) chromium hexavalent Cr(VI) - heavy metal ion (HMI), (ii) humic acid (HA) - natural organic pollutant and (iii) textile dyes - (cationic: malachite green (MG), methylene blue (MB) and anionic: congo red (CR)) have been carried out using 2D/1D (tungsten disulphide (WS2) sheets/zinc oxide (ZnO) nanorods) nanocomposite. The synthesized 2D/1D heterostructure acts as a barrier for the recombination of photogenerated species and hence, enhanced the photocatalytic activity. The synthesis of high-purity and crystalline nanocomposite was confirmed by the X-ray diffraction studies. The uniform distribution of ZnO nanorods with an average diameter and length of ∼50 and ∼280 nm, respectively on the surface of WS2 nanosheets were confirmed by Field-emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM). The photocatalytic study shows that the photocatalytic removal efficiencies significantly, enhanced using synthesized nanocomposite from 4.1% to 83.6% for Cr(VI) and 23.5%–75.0% for HA as compared to pristine WS2, respectively. The enhanced removal efficiency achieved by the synthesized nanocomposite was explained with the help of (i) higher carrier concentration, (ii) low charge transfer resistance, (iii) appropriate surface charge and (iv) large surface area (85.48 m2/g), as determined from Mott-Schottky (MSK), Electrochemical Impedance Spectroscopy (EIS), Zeta potential, and Brunauer-Emmett-Teller (BET) experiments. The significant improvement in the removal efficiencies were also attributed to the pore size of nanocomposite, pore size belongs to the micropores (0.8–2.0 nm) region which facilitates large active sites for the sorption of contaminants. The observed optical bandgap 2.32 eV of the nanocomposite makes it a favourable material for photocatalytic removal and degradation of contaminants. The semblance of active species in photocatalytic degradation was analyzed through a trapping study and shows that superoxide radicals (O2.−) are the primary species in the removal process. Further, the confirmation of active species was carried out using EPR analysis and value of g-factor is also calculated. The intermediate products during the photocatalytic degradation are analyzed using high performance liquid chromatography (HPLC) technique. The synthesized WZ nanocomposite is an effective and promising material for the treatment of wastewater in the textile, mining, and agricultural industries for getting out the cleaner production.

Molecular dynamics simulation study on the friction performance of WS2 coated copper during the scratching process

Tungsten disulfide (WS2) has been assumed to have the excellent tribological property that has the potential to be used in the field of lubricating engineering. In this study, WS2 nanosheet was coated onto the surface of the copper to improve the wear resistance. The tribological properties of WS2 coated copper system were investigated by molecular dynamics (MD) simulation to understand the wear mechanisms from the nanoscale. The mechanical response of the bare and the WS2 coated copper in the indentation process were compared firstly. Then, scratching simulation tests were performed at the various indentation depths from 1.2 Å to 11.2 Å to understand the tribological mechanism from the elastic stage to the fracture stage. The effect of the nanoindentation depth and anisotropy orientation of WS2 on friction behavior were also analyzed during the scratching process. Results show that the load-bearing capacity and wear resistance of the copper substrate were improved by the WS2 coated layer before the fracture during the nanoindentation process, while the protection of the layer failed after rupture that the out-of-plane deformation induced the increase of the friction force. Additionally, the difference of the friction force could be induced by the lattice spacing of WS2 and the energy dissipation during ultralow friction stage. The crack propagation along the Zigzag direction dominated the fracture behavior in both Armchair and Zigzag orientation. This study provides important insights into the friction mechanism of the WS2 when conducting nanoscratching process.

WS2 nanosheets decorated multi-layered MXene based chemiresistive sensor for efficient detection and discrimination of NH3 and NO2

Unsatisfactory sensing performance in terms of lack of selectivity and cross-sensitivity to humid environment remains a challenging issue for Ti3C2Tx MXene-based sensors. In this direction, the present study investigates the WS2/MXene composite-based chemiresistive sensor, utilizing the synergistic benefits of active adsorption sites of WS2 nanosheets with large surface and high conductive platform of multi-layered MXene sheets. The different weight proportions of WS2 to MXene were synthesized and a sensor fabricated using 25 wt % WS2/MXene exhibited preeminent response of 3–29 % and 6.87–44 % within range of 0.1–5 ppm NH3 and 1–100 ppb NO2, respectively. More importantly, the opposite transient response curves were observed for NH3 (increase in resistance) and NO2 (decrease in resistance), which served as a basis for their discrimination. Further, density functional theory simulations were performed to better comprehend the gas detecting capabilities of material, showing the high adsorption energies of WS2/MXene surface towards NH3 and NO2. Moreover, the humidity cross-sensitivity studies with NH3 and NO2 were also taken, and the sensor showed high resilience to humidity. Finally, an LED sensing module was employed to further distinguish the detection of NH3 and NO2, which showed the possibility of practical application of dual sensing using single sensing material.

Topochemically prepared tungsten disulfide nanostructures as a novel pseudocapacitive electrode for high performance supercapacitor

The topochemical preparation of nanostructured materials (NMs) has received significant attention in recent years due to the exceptional electrochemical properties exhibited by the resulting NMs. This work focuses on the preparation of two-dimensional tungsten di-sulfide (WS2) nanostructures through the topochemical conversion of tungsten trioxide (WO3) nanostructures and also evaluates their potential applications as electrode materials for supercapacitors (SCs). The X-ray diffraction and photoelectron studies conducted in this research reveal the conversion of hexagonal WO3 into hexagonal WS2 nanosheets, accompanied by changes in oxidation states. The FE-SEM and HR-TEM studies confirm the formation of WS2 in the sheet-like morphologies with lateral dimensions of 100 × 100 nm. The electrochemical investigation, using techniques such as CV, galvanostatic CD, and EIS, confirmed the presence of intercalation pseudocapacitance in the WS2 electrode, with a higher electrode-specific-capacitance (260 F g−1) than that of WO3 electrode. The WS2 symmetric SC delivered high device capacitance (59.17 F g−1), energy density (8.21 Wh kg−1) and power density (3,750 W kg−1) with better cyclic stability over 5000 cycles. These experimental findings show that the topochemically synthesized WS2as novel supercapacitor electrodes might be useful for the advancement of future-generation energy storage devices.

Synthesis of highly efficient novel two-step spatial 2D photocatalyst material WS2/ZnIn2S4 for degradation/reduction of various toxic pollutants

In this article, we report the synthesis, characterization of novel biofriendly 2D/2D heterostructure WS2/ZnIn2S4 material in which 2D WS2 nanosheets are uniformly distributed spatially onto the spherically arranged 2D leaves of ZnIn2S4. We then studied the in-depth photocatalytic degradation activity of this novel nanocomposite and its pristine component materials on cationic dye: malachite green, anionic dye: congo red and reduction of heavy metal: chromium(VI) and the degradation efficiency of composite material was also tested on rhodamine-B, methylene blue, methyl orange dyes and acetaminophen/paracetamol drug. Form factor, structure factor and shape factor analysis has been carried out using X-ray diffractometry (XRD). Bond vibrations, functional groups and phonon vibration mode analysis has been done based on Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy. Morphological and compositional analysis has been done using field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDAX) and X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM). Surface area and pore size/distribution was characterized using Brunauer–Emmett–Teller (BET) method and Barrett-Joyner-Halenda Model. Degradation pathways and intermediate products are proposed using the high-performance liquid chromatography (HPLC). Photocatalytic activity of the nanocomposite WS2/ZnIn2S4 is compared with pristine ZnIn2S4 and pristine WS2, which shows more than 50% enhancement in both efficiency and rate of degradation/reduction for all the pollutants. A scavenger study was carried out to get insight of primary and secondary reactive oxygen species (ROS) taking part in degradation. Exciton lifetime, surface charge and stability, and flat band positions were studied based on time-correlated single photon counting (TCSPC) also known as time-resolved photoluminescence (TRPL), zeta potential, and Mott-Schottky respectively. Rate kinetics study was performed to analyze the physical and chemical behaviour of the nanocomposite with pollutants in consideration. Results show ∼100%, ∼90%, and ∼95% degradation efficiency by the heterostructure for malachite green (MG), congo red (CR), and reduction of heavy metal chromium (Cr(VI)) respectively within 5 min, which is a huge improvement as compared to pristine WS2 and pristine ZnIn2S4, both of which show the efficiencies of only ∼25% to∼75% in all the cases.

Synergetic electrochemical performance of tungsten oxide/tungsten disulfide/MWCNTs for high-performance aqueous asymmetric supercapattery devices

In this work, a binary WO3/WS2 nanocomposite is synthesized by a single-step sulfurization of WO3 through chemical vapor deposition (CVD) process. Then the synthesized composite was blended with MWCNTs to produce a WO3/WS2/MWCNTs ternary composite for a high-performance supercapacitor. X-ray diffraction, Raman, and X-ray photoelectron spectroscopy were used to investigate comprehensively structural characteristics and chemical bonding of the synthesized nanocomposite. FESEM reveals that agglomeration of 1D MWCNTs, and 2D WS2 nanosheets with WO3 nanoparticles enhance the surface area as well as conductivity of electrode material which in turn leads to superior electrochemical properties of the ternary nanocomposite. The electrochemical measurements suggest that the WO3/WS2/MWCNTs composite is the best-optimized electrode with a specific capacitance of 517 C/g. By employing the optimized electrode as positive and activated carbon (AC) treated as a negative electrode an asymmetric supercapattery (ASC) device was assembled. The ASC device displays a high energy density of 86 Wh/kg and power density of 11828 W/kg with only 5 % degradation in initial capacitance after 5000 continuous cycles. In conclusion, composting is a promising approach to boost the overall performance of supercapacitors.

Augmented photocatalytic water splitting performance of CdS nanorods encased with Co-C@WS2 nanostructures

Hydrogen production via photocatalytic water-splitting process is a favourable and eco-friendly technique which addresses the energy-environmental issues. However, the development of affordable, highly efficient as well as stable photocatalysts continues to be a challenging task. Here, we propose a photocatalyst based on CdS nanorods that are coupled with WS2 nanosheets and metal-organic framework (MOF) derived Co-C nanostructures to promote photo-assisted H2 evolution in the aqueous medium. The experimental outcomes demonstrate that the fabricated nanocomposite is highly active to produce H2 at a rate of 214.96 mmol. g−1. h−1, indicating highest values among CdS-based photocatalysts. Additionally, the nanocomposite displayed an excellent long-term stability for 40 h. Overall, the present work introduces a photocatalytic system devoid of noble-metals, illustrating the functionalities of MOF-derived materials along with 2D transition metal dichalcogenides for accelerating the H2 evolution rate of semiconductor photocatalysts.