WS2 Hybrid Structures

Rate performances at various current densities and EIS spectra-cycling stability image

In WS2 hybrid structures, atomic doping is one of the effective ways to change the physical and chemical properties of the material, such as band gap and optical properties. For example, Sasaki et al. demonstrated that the exciton absorption peaks at 1.94 and 2.34 eV, respectively, were broadened by Nb doping. This suggests that excitons in WS2 monolayers are sensitive to Nb doping because of the enhancement of the inhomogeneous broadening rate.

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IF-WS2 and NT-WS2 of WS2 Nanomaterials and Preparation

CV curves of the first three cycles for the WG electrode and first three galvanostatic charge-discharge profiles of the WG composite image

Various forms of WS2 nanomaterials include nanosheets, IF-WS2, NT-WS2, and other forms. Chemical gas-solid reactions are the most well-known and established method for the synthesis of IF WS2 nanoparticles and nanotubes. Tenne et al. initially synthesized IF WS2 nanoparticles and nanotubes using WO3 films and H2S in a reducing atmosphere (95% N2 + 5% H2) at 850 °C. However, only a small amount of products could be synthesized by this method.

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Most Common Form of Tungsten Disulfide Nanomaterials: Nanosheets

Polarization curves of WS2-RGO hybrid nanosheets and corresponding Tafel plots recorded on glassy carbon electrodes image

Nanosheets of tungsten disulfide nanomaterials are the most common form, and the main synthetic strategies can be divided into two categories: top-down and bottom-up approaches. Top-down approaches allow the production of small amounts or single-layer samples at a lower cost, which is very beneficial for basic research. Among these top-down methods, mechanical peeling via Scotch tape is the simplest method, with only a few or single layers of WS2 exfoliated via Scotch tape.

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Controlled Synthesis of Tungsten Disulfide Nanomaterials

Polarization curves and corresponding Tafel plots of bulk of WS2 WS2 nanofakes and WS2 nanorattles image

1T-WS2 structure and 2H-WS2 structure of tungsten disulfide nanomaterials controlled synthesis is important. The 1T-WS2 structure is considered an efficient co-catalyst for hydrogen evolution due to the increased density of catalytic active sites and the metal conductivity, while the 2H-WS2 structure can be used as a visible photosensitizer. Therefore, various synthetic methods for the crystalline phase modulation of WS2 have received much attention. Since the conversion from 1T-WS2 to stable 2H-WS2 can be easily achieved by annealing, the study of feasible methods to achieve the opposite conversion has received much attention.

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Electrical Characteristic and HER Mechanism of Tungsten Disulfide Nanomaterials

Schematic illustration of the forming process of WS2 samples with different morphologies image

Due to the promising applications of tungsten disulfide nanomaterials in the field of energy conversion and storage, efforts have been made to study and improve its electrical characteristic and HER mechanism of WS2, such as carrier concentration (p), mobility (μ), and resistivity (ρ). According to theoretical predictions, WS2 has the highest electron mobility in semiconductor TMDCs due to the reduced effective mass.

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Light Absorption and Photocatalytic Characteristics of Tungsten Disulfide Nanomaterials

Schematic description of the main liquid exfoliation and ALD mechanisms image

Compared with semiconducting materials, tungsten disulfide nanomaterials exhibit higher light absorption, and photocatalytic properties are another important property. For semiconductor materials, light absorption properties are very important, especially for photocatalysis. When WS2 absorbs photons, transitions between in-band, out-of-band, and impurity defects occur, which can form specific absorption spectra. The characteristic absorption peak of bulk WS2 is near the wavelength of 910 nm and is located in the near-infrared (NIR) region. By forming nanostructures, a blue shift of the WS2 characteristic absorption peak can be observed.

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Tungsten Disulfide Nanomaterials Applied in Energy Conversion and Storage

Schematic illustration of absolute band positions with respect to the vacuum level image

Due to the rapid growth of the global population and rapid socio-economic development, energy and environmental issues have received widespread attention. As a transition metal disulfide, tungsten disulfide nanomaterials have made important research advances in the field of energy conversion and storage. Given the versatility and rich microstructure of these materials, the plasticity and controlled synthesis of tungsten disulfide (WS2) nanomaterials are of interest to researchers.

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Crystal Structures of Tungsten Disulfide and Tungsten Diselenide

Top and side views of a repeated unit cell of 2D tungsten diselenide image

An article published in the Journal of Solid State Chemistry by Schutte et al. illustrates that crystal structures of tungsten disulfide (WS2) and tungsten diselenide (WSe2) host the same type of layered structure as molybdenum disulfide (MoS2). In addition to the common hexagonal 2H form of WS2, a rhombohedral form, 3R-WS2, has also been reported, which is isotypic to the rhombohedral form of MoS2.

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Crystal Structure of Tungsten Disulfide

Proposed reaction mechanism for photocatalytic H2 production on the WS2-CdS catalyst image

The crystal structure of tungsten disulfide (WS2) belongs to the P63/mmc space group with lattice parameters of a = 0.31532 nm and c = 1.2323 nm measured by X-ray diffraction. As a typical representative of two-dimensional layered transition metal dichloride (TMDC) materials with a structure consisting of 0.6-0.7 nm thick X-M-X interlayers (M is transition metal; X = S, Se, Te).

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Application of Tungsten Disulfide Nanomaterials in Cancer Therapy

Cancer treatment options image

In recent years, tungsten disulfide nanomaterials (WS2NM) have had important applications in cancer therapy. Researchers have synthesized chitosan-functionalized WS2 nanocomposites (CS/ WS2/Ru) implanted with ruthenium nanoparticles. Chitosan is biocompatible and non-toxic, making it an excellent candidate for drug delivery systems. On the other hand, the biological properties of chitosan can be improved due to the small size and large surface area of WS2.

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