Owing to unique physical and chemical properties, transition metal dichalcogenides (TMDs) attract research interest. Among the family of TMDs, tungsten disulfide (WS₂) has a unique band structure due to its semiconductor properties; i.e., its broadband spectral response characteristics, ultra-fast bleaching recovery time, and excellent saturable light absorption.

The atomic structure of tungsten disulfide (WS₂) consists of a stack of three layers formed by a transition metal layer (W atom) sandwiched between two S-atom layers, each with a hexagonal lattice structure. In the three-layer stack, W and S atoms are bonded together by strong ion-covalent bonds. WS₂ formed by these three layers is held together by weak van der Waals interactions, which allow mechanical exfoliation of the WS₂ layer. In the bulk phase, polymorphism is a unique feature of TMDs.

Alloys are metals made by combining two or more metallic elements, primarily to provide greater strength or corrosion resistance. The tungsten alloy family has many industrial applications due to its strength. Tungsten offers a unique contribution because it imparts exceptional strength, corrosion resistance and other useful properties to base metals. In addition to being an excellent alloying element, tungsten can also serve as the basis for its own alloys, and this article will focus on the basic categories of these tungsten alloys. Below are some details on the 3 most common tungsten alloys widely used in industry. Their properties and applications will also be introduced.

The current applications on WS₂ nanomaterials still face challenges and should be investigated in depth in the following aspects. Firstly, the study mechanism of HER needs to be deepened and clarified in terms of the fundamental properties of WS₂. Advanced characterization methods, such as in situ techniques, can be combined to analyze the structural changes of the material during the catalytic process and reveal the catalytic process of WS₂-based nanomaterials, especially electrocatalysis.

Recently, researchers demonstrated a specific capacitance of 398.5 F.g^-1 for sheet tungsten disulfide anode materials. However, the performance of these materials remains unsatisfactory. Encouragingly, Nagaraju et al. synthesized WS₂ nanoparticles used as supercapacitor electrode materials, which provided a high capacitance value of 1439.5 F.g^-1 at a current density of 5 mA.cm^-2 and maintained excellent cycling stability of 77.4% after 3000 cycles. This result suggests that WS₂ can be considered a promising candidate for supercapacitor electrode materials.

Tungsten disulfide possesses a much larger interlayer spacing of 0.62 nm than that of graphite (0.34 nm). This would be very favorable for the reversible process of Na⁺ intercalation/de-intercalation, making WS₂ a promising anode material for sodium-ion batteries (SIBs). For example, Liu et al. reported WS₂ nanowires (NWs) with an expanded interlayer spacing of 0.83 nm.

As potential high-capacity anode materials for Lithium-ion batteries (LIBs), TMDCs have gained considerable attention, especially WS2 nanomaterials, which exhibit a higher theoretical specific capacity (433 mAh.g-1) than commercial graphite due to the 2D layer structure and the large platelet space. When used as an anode for lithium-ion batteries, WS2 exhibits an increasing lithium storage capacity. For example, Liu et al. prepared an ordered mesoporous WS2 as an anode for LIBs, which showed a high lithium storage capacity of 805 mAh.g-1 at a current of 0.1A.g-1.

Tungsten disulfide (WS2) is a semiconductor with a band gap, which gives WS2 a wide range of light absorption, and therefore, WS2 can be considered a promising photocatalyst for photocatalysis degradation of organic pollutants and hydrogen production from water decomposition. WS2 extends the light absorption region to the long-wave direction, and through morphological tuning, WS2 can achieve near-infrared photocatalytic activity.

WS₂ has attracted much attention due to its unique structural properties and suitable hydrogen binding energy (comparable to platinum group metals). WS₂ nanomaterials have been extensively investigated for energy conversion and storage systems.