Morphology Control of TiO Nanorods Using KBr Salt for Enhancing the Photocatalytic Activity of TiO and MoS/TiO Heterostructures.

In this study, the effect of KBr salt on the growth of TiO nanorods (NRs) was systematically studied. The addition of KBr with different concentrations provides a controllable growth of TiO NRs using hydrothermal method. The results revealed that the presence of KBr molecules affects the growth rate by suppressing the growth in the lateral direction and allowing for axial growth. This results in affecting the morphology by decreasing the diameter of the nanorods, and increasing the free space between them. Enhancing the free spaces between the adjacent nanorods gives rise to remarkable increase in the internal surface area, with more exposure side surface. To obtain benefit from the enlargement in the inner surface area, TiO NRs were used for the preparation of MoS/TiO heterostructures. To study the influence of the morphology on their activity, TiO NRs samples with different KBr concentrations as well as the MoS/TiO heterostructures were evaluated towards the photocatalytic degradation of Rhodamine B dyes.Open Access funding provided by Qatar National Library

Recent Progress in WS2 -Based Nanomaterials Employed for Photocatalytic Water Treatment

Water pollution is one of the most serious environmental issues globally due to its harmful consequences on the ecosystem and public health. Various technologies have been developed for water treatment such as photocatalysis, which has recently drawn scientists’ attention. Photocatalytic techniques using semiconductors have shown an efficient removal of various water contaminants during water treatment as well as cost effectivity and low energy consumption. Tungsten disulfide (WS2) is among the promising Transition Metal Dichalcogenides (TMDs) photocatalysts, as it has an exceptional nanostructure and special properties including high surface area and high carrier mobility. It is usually synthesized via hydrothermal technique, chemical vapor deposition (CVD), and liquid-phase exfoliation (LPE) to obtain a wide variety of nanostructures such as nanosheets and nanorods. Most common examples of water pollutants that can be removed efficiently by WS2-based nanomaterials through semiconductor photocatalytic techniques are organic contaminants, pharmaceuticals, heavy metals, and infectious microorganisms. This review summarizes the most recent work on employing WS2-based nanomaterials for different photocatalytic water treatment processes.Open Access funding provided by Qatar National Library

PREPARATION OF WS2/TIO2 NANOSTRUCTURES FOR PHOTOCATALYTIC 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 and the environmental issues. One of the promising routes is the semiconductor-based solar driven photocatalysis, which is believed to address several critical issues such as the production of sustainable chemical fuel, and the degradation of toxic pollutant dyes. Among various materials, oxide semiconductors, and especially TiO2 have been extensively studied and used as a photocatalyst, owing to its advantages such as low cost, nontoxicity, and chemical stability. However, the application of TiO2 as a photocatalyst is limited by some shortcomings such as high rate of electron-hole recombination and the relatively wide band gap that prevents the absorption of visible light. Therefore, some strategies are required to overcome these limitations. Various techniques and strategies have been constructed to overcome the drawbacks of TiO2 material such as nanostructured morphology and the construction of heterostructures. In this work, the photocatalytic performance of TiO2 was enhanced through two main routes. The first route is providing a controllable growth over the hydrothermally grown TiO2 nanorods. In this regard, the effect of KBr salt on the growth of TiO2 nanorods (NRs) was systematically studied. The results revealed that the presence of KBr molecules affects the growth rate by suppressing the growth in the lateral direction and allowing for axial growth. This results in affecting the morphology by decreasing the diameter of the nanorods, and increasing the free space between them. Enhancing the free spaces between the adjacent nanorods gives rise to a remarkable increase in the internal surface area, with more exposure side surface. The second route of enhancing the TiO2 photocatalytic activity is the construction of heterostructure. To get benefit from the enlargement in the inner surface area of the hydrothermally grown TiO2 NRs, WS2 nanoflakes / TiO2 nanorods heterostructure was obtained by optimizing the height between the precursor and the substrate, which provides a control over the size of the flakes. In addition, the achieved WS2/TiO2 heterostructures were evaluated as photocatalysts for Rhodamine B degradation, and photoelectrochemical activity (PEC)

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