Exfoliated−Restacked Phase of WS<sub>2</sub>

Tsai, Hui Lien; Heising, Joy; Schindler, J. L.; Kannewurf, Carl R.; Kanatzidis, Mercouri G.

doi:10.1021/cm960579t

Cited by 172 publications

(148 citation statements)

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“…33,34 This process leads to the formation of colloidal suspensions of mono-and fewlayered nanosheets (Figure 1a). The photoanodes were prepared by restacking the exfoliated nanosheets from solution onto F:SnO 2 doped glass (FTO).…”

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confidence: 99%

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MoS₂/WS₂ Heterojunction for Photoelectrochemical Water Oxidation

et al. 2017

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The solar-assisted oxidation of water is an essential half reaction for achieving a complete cycle of water splitting. nanosheets results in a 10-fold increase in incident-photon-to-current-efficiency compared to the individual constituents. This proves that charge carrier lifetime is tailorable in atomically thin crystals by creating heterojunctions of different compositions and architectures. Our results suggest that the MoS 2 and WS 2 nanosheets and their bulk heterojunction blend are interesting photocatalytic systems for water oxidation, which can be coupled with different reduction processes for solar-fuel production.

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Section: Resultsmentioning

confidence: 99%

“…Figure 1a). 33,34 The suspension was sonicated using a VWR USC300T sonic bath (80W) for 30 minutes at 0°C…”

Section: Discussionmentioning

confidence: 99%

MoS₂/WS₂ Heterojunction for Photoelectrochemical Water Oxidation

et al. 2017

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“…Such chemical exfoliation methods produce gram quantities of submicrometre-sized monolayers 52 , but the resulting exfoliated material differs structurally and electronically from the bulk material 49 . In particular, for MoS 2 the process changes the electronic structure of the exfoliated nanosheets from semiconducting to metallic, and the Mo atom coordination is changed from trigonal prismatic (2H-MoS 2 ) to octahedral (1T-MoS 2 ) 49,[53][54][55] .…”

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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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“…The anisotropic form originates from the diffraction of the X-ray beam by a lattice with two dimensional translation symmetry without any ordering in the third dimension. [34][35][36] Therefore, the peak shape is the first indicator for the absence of order in the third dimension, signifying turbostratic 6 disorder. A similar conclusion can be drawn from the out-of-plane PXRD, where the pellets of [RuCl 3 ] x-and t-RuCl 3 feature an exponential intensity decay for the series of (00l) reflections with higher order.…”

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Magnetic Properties of Restacked 2D Spin 1/2 honeycomb RuCl₃ Nanosheets

et al. 2016

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Spin 1 2 honeycomb materials have gained substantial interest due to their exotic magnetism and possible application in quantum computing. However, in all current materials out-of-plane interactions are interfering with the in-plane order, hence a true 2D magnetic honeycomb system is still of demand. Here, we report the exfoliation of the magnetic semiconductor α-RuCl 3 into the first halide monolayers and the magnetic characterization of the spin 1 2 honeycomb arrangement of turbostratically stacked RuCl 3 monolayers. The exfoliation is based on a reductive lithiation/hydration approach, which gives rise to a loss of cooperative magnetism due to the disruption of the spin 1 2 state by electron injection into the layers. After an oxidative treatment, cooperative magnetism similar to the bulk is restored. The oxidized pellets of restacked single layers feature a magnetic transition at T N = 7 K in the in-plane direction, while the magnetic properties in the out-of-plane direction vastly differ from bulk α-RuCl 3 . The macro- Binary halide nanosheets have been predicted based on chemical intuition 3,4 or ab initio calculations. 7 Yet, no single layer halides have been synthesized so far, even though this class of compounds features an array of interesting electrical and magnetic properties.The magnetic semiconductor α-RuCl 3 is one such example. While it was investigated in the past as a host for intercalants 8,9 and as a lithium ion conductor, 10 current research focuses on its magnetic properties. Due to its layered honeycomb structure of spin 1 2 Ru 3+ centers in combination with spin orbit coupling (SOC), it is one of the few known materials featuring a zigzag antiferromagnetic (AF) ground state below a temperature of T N1 = 8 K. [11][12][13] In the zigzag order, the magnetic moments form ferromagnetic (FM) zigzag chains, whose magnetization direction is opposed to the neighboring chains within the plane. Additionally, there is a further magnetic phase transition observed at T N2 = 14 K. The origin of this transition is currently still under debate. This type of ordering was first observed in Na 2 IrO 3 14-16 and explained by the Kitaev-Heisenberg model, 17,18 which describes that a frustrated spin 1 2 honeycomb arrangement could lead to a variety of interesting spin structures. Based on the competition among the exchange interactions up to the third neighbor, the system could possibly be pushed into a quantum spin liquid regime by the manipulation of the competing interactions, thereby opening up applications in quantum computing. 17,19 Yet, the Na + ions in the interlayer space of Na 2 IrO 3 lead to disadvantageous interactions between the iridate layers, which interfere with theoretical predictions of a honeycomb arrange-2 ment of spin 1 2 magnetic arrays. 20 Eliminating the interlayer interaction could provide a route to manipulate the spin structure of real materials featuring a spin 1 2 honeycomb arrangement. In RuCl 3 , where no charged ions are in between the honeycomb layers, the interlayer in...

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Exfoliated−Restacked Phase of WS₂

Cited by 172 publications

References 16 publications

MoS₂/WS₂ Heterojunction for Photoelectrochemical Water Oxidation

MoS₂/WS₂ Heterojunction for Photoelectrochemical Water Oxidation

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides

Magnetic Properties of Restacked 2D Spin 1/2 honeycomb RuCl₃ Nanosheets

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Exfoliated−Restacked Phase of WS2

Cited by 172 publications

References 16 publications

MoS2/WS2 Heterojunction for Photoelectrochemical Water Oxidation

MoS2/WS2 Heterojunction for Photoelectrochemical Water Oxidation

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides

Magnetic Properties of Restacked 2D Spin 1/2 honeycomb RuCl3 Nanosheets

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Exfoliated−Restacked Phase of WS₂

MoS₂/WS₂ Heterojunction for Photoelectrochemical Water Oxidation

MoS₂/WS₂ Heterojunction for Photoelectrochemical Water Oxidation

Magnetic Properties of Restacked 2D Spin 1/2 honeycomb RuCl₃ Nanosheets