Photosensitization of Nanostructured TiO<sub>2</sub> with WS<sub>2</sub> Quantum Sheets

Thomalla, Markus; Tributsch, H.

doi:10.1021/jp061371q

Cited by 86 publications

(55 citation statements)

References 26 publications

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“…A bulk heterojunction solar cell made from TiO 2 nanoparticles, MoS 2 atomic layer nanosheets and poly(3-hexylthiophene) (P3HT) was recently demonstrated with 1.3% photoconversion efficiency 145 . Similarly, electrochemical solar cells with TiO 2 were sensitized with WS 2 , which acts as a stable, inorganic absorber material 146,147 . TMDCs have also been demonstrated as conductors and electron-blocking layers in polymer LEDs 53,148 .…”

Section: Optoelectronicsmentioning

confidence: 99%

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides

et al. 2012

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699M any two-dimensional (2D) materials exist in bulk form as stacks of strongly bonded layers with weak interlayer attraction, allowing exfoliation into individual, atomically thin layers 1 . The form receiving the most attention today is graphene, the monolayer counterpart of graphite. The electronic band structure of graphene has a linear dispersion near the K point, and charge carriers can be described as massless Dirac fermions, providing scientists with an abundance of new physics 2,3 . Graphene is a unique example of an extremely thin electrical and thermal conductor 4 , with high carrier mobility 5 , and surprising molecular barrier properties 6,7 .Many other 2D materials are known, such as the TMDCs 8,9 , transition metal oxides including titania-and perovskite-based oxides 10,11 , and graphene analogues such as boron nitride (BN) 12,13 . In particular, TMDCs show a wide range of electronic, optical, mechanical, chemical and thermal properties that have been studied by researchers for decades 9,14,15 . There is at present a resurgence of scientific and engineering interest in TMDCs in their atomically thin 2D forms because of recent advances in sample preparation, optical detection, transfer and manipulation of 2D materials, and physical understanding of 2D materials learned from graphene.The 2D exfoliated versions of TMDCs offer properties that are complementary to yet distinct from those in graphene. Graphene displays an exceptionally high carrier mobility exceeding 10 6 cm 2 V -1 s -1 at 2 K (ref. 16) and exceeding 10 5 cm 2 V -1 s -1 at room temperature for devices encapsulated in BN dielectric layers 5 ; because pristine graphene lacks a bandgap, however, fieldeffect transistors (FETs) made from graphene cannot be effectively switched off and have low on/off switching ratios. Bandgaps can be engineered in graphene using nanostructuring [17][18][19] , chemical functionalization 20 and applying a high electric field to bilayer graphene 21 , but these methods add complexity and diminish mobility. In contrast, several 2D TMDCs possess sizable bandgaps around 1-2 eV (refs 9,14), promising interesting new FET and optoelectronic devices.TMDCs are a class of materials with the formula MX 2 , where M is a transition metal element from group IV (Ti, Zr, Hf and so on), group V (for instance V, Nb or Ta) or group VI (Mo, W and so on), and X is a chalcogen (S, Se or Te). These materials form layered structures of the form X-M-X, with the chalcogen atoms in two hexagonal planes separated by a plane of metal atoms, as shown in Fig. 1a. Adjacent layers are weakly held together to form the bulk crystal in a variety of polytypes, which vary in stacking orders and metal atom coordination, as shown in Fig. 1e. The overall symmetry of TMDCs is hexagonal or rhombohedral, and the metal atoms have octahedral or trigonal prismatic coordination. The electronic properties of TMDCs range from metallic to semiconducting, as summarized in Table 1. There are also TMDCs that exhibit exotic behaviours such as charge density waves ...

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Section: Optoelectronicsmentioning

confidence: 99%

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides

et al. 2012

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“…Among TMDs, WS 2 has been studied intensively. It is an indirect-gap semiconductor in its bulk form, while it shows a transition to direct-gap character in its monolayer form [24][25][26]. It was shown by Ramasubramaniam that the optoelectronic properties of WS 2 and MoX 2 (X=S or Se) monolayers are tunable through quantum confinement of carriers within the monolayers [27].…”

Section: Introductionmentioning

confidence: 99%

Mg(OH)2−WS2 van der Waals heterobilayer: Electric field tunable band-gap crossover

et al. 2016

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Magnesium hydroxide [Mg(OH) 2 ] has a layered brucitelike structure in its bulk form and was recently isolated as a new member of two-dimensional monolayer materials. We investigated the electronic and optical properties of monolayer crystals of Mg(OH) 2 and WS 2 and their possible heterobilayer structure by means of first-principles calculations. It was found that both monolayers of Mg(OH) 2 and WS 2 are direct-gap semiconductors and these two monolayers form a typical van der Waals heterostructure with a weak interlayer interaction and a type-II band alignment with a staggered gap that spatially separates electrons and holes. We also showed that an out-of-plane electric field induces a transition from a staggered to a straddling-type heterojunction. Moreover, by solving the Bethe-Salpeter equation on top of single-shot G 0 W 0 calculations, we show that the low-energy spectrum of the heterobilayer is dominated by the intralyer excitons of the WS 2 monolayer. Because of the staggered interfacial gap and the field-tunable energy-band structure, the Mg(OH) 2 −WS 2 heterobilayer can become an important candidate for various optoelectronic device applications in nanoscale.

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“…It forms sandwich interlayer structure created by S-Mo-S layers, which are loosely bound to each other only by van der Waals forces (Rapoport et al 2005). Such structures, at the bulk and nanoscale, exhibit a broad array of applications, such as electrochemical hydrogen storage (Chen et al 2001), cathode material for rechargeable lithium batteries and solar cells (Imanishi et al 1992;Thomalla and Tributsch 2006), electric transport (Kopnov et al 2006), useful solid lubricant (Rapoport et al 2003), an intercalation host (Aharon et al 2006), and field emission tips (Nemanic et al 2003). For example, molybdenum disulfide may be an alternative material for next-generation nanoelectronic devices viz., transistor (Radisavljevic et al 2011) and tandem photovoltaic configurations because its electronic properties are superior to silicon (Li et al 2005) and its band gap transforms from indirect to direct at nanoscale.…”

Section: Introductionmentioning

confidence: 99%

Innovative biofilm inhibition and anti-microbial behavior of molybdenum sulfide nanostructures generated by microwave-assisted solvothermal route

et al. 2014

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The incessant use of antibiotics against infectious diseases has translated into a vicious circle of developing new antibiotic drug and its resistant strains in short period of time due to inherent nature of microorganisms to alter their genes. Many researchers have been trying to formulate inorganic nanoparticles-based antiseptics that may be linked to broad-spectrum activity and far lower propensity to induce microbial resistance than antibiotics. The way-out approaches in this direction are nanomaterials based (1) bactericidal and (2) bacteriostatic activities. We, herein, present hitherto unreported observations on microbial abatement using non-cytotoxic molybdenum disulfide nanostructures (MSNs) which are synthesized using microwave assisted solvothermal route. Inhibition of biofilm formation using MSNs is a unique feature of our study. Furthermore, this study evinces antimicrobial mechanism of MSNs by reactive oxygen species (ROS) dependent generation of superoxide anion radical via disruption of cellular functions.

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Photosensitization of Nanostructured TiO₂ with WS₂ Quantum Sheets

Cited by 86 publications

References 26 publications

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides

Mg(OH)2−WS2 van der Waals heterobilayer: Electric field tunable band-gap crossover

Innovative biofilm inhibition and anti-microbial behavior of molybdenum sulfide nanostructures generated by microwave-assisted solvothermal route

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Photosensitization of Nanostructured TiO2 with WS2 Quantum Sheets

Cited by 86 publications

References 26 publications

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides

Mg(OH)2−WS2 van der Waals heterobilayer: Electric field tunable band-gap crossover

Innovative biofilm inhibition and anti-microbial behavior of molybdenum sulfide nanostructures generated by microwave-assisted solvothermal route

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Photosensitization of Nanostructured TiO₂ with WS₂ Quantum Sheets