Carbon Free Nanostructured Plate like WS 2 with Excellent Lithium Storage Properties

Experimental and theoretical insights into the supercapacitive performance of interconnected WS2 nanosheets

Transition metal dichalcogenides (TMDs) are fascinating and prodigious considerations in the electrochemical energy storage sector because of their two dimensional chemistry as well as heterogeneous characteristics. Herein, we synthesized interconnected WS2 nanosheets by a hydrothermal method followed by sulphuration at 850 °C in an argon atmosphere. The ultrathin WS2 nanosheet array is endowed with an excellent specific capacitance of 74 F g-1 at the current density of 3 A g-1 up 7000 cycles. Moreover, a symmetric supercapacitor was fabricated using WS2 nanosheets, which provided the admirable high specific capacity of 6.3 F g-1 at 0.05 A g-1 with the energy and power density of 5.6 × 102 mW h kg-1 and 3.6 × 10 5 mW kg-1, respectively. Density functional theory (DFT) simulations revealed the presence of populated energy states near the Fermi level resulting in a high quantum capacitance value, which supports the experimentally achieved high capacitance value. The attained results recommend interconnected WS2 nanosheets as a novel, robust, and low-cost electrode material for supercapacitor energy storage devices.

Sandwich-type architecture film based on WS2 and ultrafast self-expanded and reduced graphene oxide in a Li-ion battery

Since its discovery, graphene has been widely considered a great material that has advanced the Li-ion battery field and allowed development in its performance. However, most current graphene-related research is focused on graphene-based composites as electrode materials, highlighting the role of graphene in composite materials. Herein, we focused on a three-dimensional composite film with unique sandwich-type architecture based on ultrafast self-expanded and reduced graphene oxide (userGO) and exfoliated WS₂. This strategy allows non-active agents [e.g., carbon black and poly (vinylidene fluoride)] free electrodes in LIBs in the form of a film. The ultra-quick exothermal nature of the USER reaction allows the rapid release of internally generated gases to create highly porous channels inside the film. Hence, the improved Li-ion transport in the LIBs boosted the electrochemical performance of both film components (ex-WS₂ and reduced graphene), resulting in a high specific capacity of 762 mAh/g at .05 A/g and high Coulombic efficiency (101%) after 1,000 cycles. Overall, userGO showed the highest capacity at a low current, and ex-WS₂ provided a higher reversible capacity. These results showed that the expanded graphene layer is an excellent shield for ex-WS₂ to protect against pulverization, promoting both stability and capacity.

Differential pulse voltammetry determination of salbutamol using disulfite tungsten/activated carbon modified glassy carbon electrode

In the present article, the disulfide tungsten/activated carbon derived from Eichhornia crassipes (WS₂/AC) was synthesized by the hydrothermal process. The received materials were examined by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray - mapping, and nitrogen adsorption/desorption isotherms. The morphology of WS₂/AC was tailored to have a micro/meso/macro structure that facilized large electric conductivity and quick ion diffusion. The WS₂/AC sample was used as an electrode modifier for developing an electrochemical sensor for salbutamol detection. WS₂/AC exhibited excellent oxidation toward salbutamol. Through some optimized conditions, the electrochemical signal of the proposed sensor varied linearly to the salbutamol concentration ranging from 1 to 210 μM with a low LOD (detection limit) of 0.52 μM. The developed sensor showed several merits: easy producing, convenient usage, fabulous selectivity, and good repeatability as well as reproducibility. Finally, the suggested technique can be applied to determine salbutamol in people's biological fluid with satisfactory recoveries of 98.5-104.4% and without statistics different from standard HPLC.

Recent Advances in WS2 and Its Based Heterostructures for Water-Splitting Applications

The energy from fossil fuels has been recognized as a main factor of global warming and environmental pollution. Therefore, there is an urgent need to replace fossil fuels with clean, cost-effective, long-lasting, and environmentally friendly fuel to solve the future energy crisis of the world. Therefore, the development of clean, sustainable, and renewable energy sources is a prime concern. In this regard, solar energy-driven hydrogen production is considered as an overriding opening for renewable and green energy by virtue of its high energy efficiency, high energy density, and non-toxicity along with zero emissions. Water splitting is a promising technology for producing hydrogen, which represents a potentially and environmentally clean fuel. Water splitting is a widely known process for hydrogen production using different techniques and materials. Among different techniques of water splitting, electrocatalytic and photocatalytic water splitting using semiconductor materials have been considered as the most scalable and cost-effective approaches for the commercial production of sustainable hydrogen. In order to achieve a high yield of hydrogen from these processes, obtaining a suitable, efficient, and stable catalyst is a significant factor. Among the different types of semiconductor catalysts, tungsten disulfide (WS2) has been widely utilized as a catalytic active material for the water-splitting process, owing to its layered 2D structure and its interesting chemical, physical, and structural properties. However, WS2 suffers from some disadvantages that limit its performance in catalytic water splitting. Among the various techniques and strategies that have been constructed to overcome the limitations of WS2 is heterostructure construction. In this process, WS2 is coupled with another semiconducting material in order to facilitate the charge transfer and prevent the charge recombination, which will enhance the catalytic performance. This review aims to summarize the recent studies and findings on WS2 and its heterostructures as a catalyst in the electrocatalytic and photocatalytic water-splitting processes.