Functionalization of Two‐Dimensional Transition‐Metal Dichalcogenides

Chen, Xin; McDonald, Aidan R.

doi:10.1002/adma.201505345

Cited by 195 publications

(175 citation statements)

References 49 publications

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“…In monolayer MoS 2 (thickness ≈0.6 nm), the band gap becomes direct with a width of 1.8 eV. [1] Importantly, to meet the requirements of different applications, properties of MoS 2 and other TMDCs can be tuned by controlling the thickness, [1] doping and alloying, [5][6][7][8] surface modification and functionalization, [9][10][11] strain, [12,13] and by creating heterostructures with other 2D materials. [6,[14][15][16] The appealing properties of TMDCs have led to a wide range of proposed applications.…”

Section: Doi: 101002/admi201700123mentioning

confidence: 99%

Atomic Layer Deposition of Crystalline MoS₂ Thin Films: New Molybdenum Precursor for Low‐Temperature Film Growth

Mattinen

Hatanpää

Sarnet

et al. 2017

Adv Materials Inter

105

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Compared to the most well-known 2D material, graphene, which is a semi-metal, the semiconducting 2H phase of MoS 2 is advantageous in having a band gap suitable for electronic applications. In bulk form, MoS 2 has an indirect band gap of 1.3 eV, which increases as a function of decreasing film thickness. In monolayer MoS 2 (thickness ≈0.6 nm), the band gap becomes direct with a width of 1.8 eV. [1] Importantly, to meet the requirements of different applications, properties of MoS 2 and other TMDCs can be tuned by controlling the thickness, [1] doping and alloying, [5][6][7][8] surface modification and functionalization, [9][10][11] strain, [12,13] and by creating heterostructures with other 2D materials. [6,[14][15][16] The appealing properties of TMDCs have led to a wide range of proposed applications. MoS 2 has been extensively studied as a channel material in conventional field-effect transistors, [17][18][19][20][21] as well as phototransistors and other optoelectronic devices. [16,21,22] The 2D structure of TMDCs plays a crucial role in possible applications relying on more exotic quantum phenomena, such as valleytronics. [23,24] MoS 2 has also shown promise in, for example, catalysis, [25] batteries, [26] photovoltaics, [27] sensors, [28] and medicine. [29] The production of high-quality, large-area MoS 2 films with a thickness controllable down to a monolayer, as required in many of the aforementioned applications, still remains a major challenge. Additionally, in many cases, the processing temperature should be kept as low as possible in order to avoid damaging sensitive substrates, such as polymers or nanostructures. Initially, flakes of monolayer MoS 2 were produced from natural MoS 2 crystals using micromechanical exfoliation, a topdown method capable of producing high-quality monolayers, albeit with poor throughput as well as limited control over flake thickness and dimensions. [4,30,31] Liquid-phase exfoliation of bulk crystals, on the other hand, offers good scalability, but often suffers from limited flake size, poor crystallinity, or contamination. [4,31,32] Bottom-up methods offer a more controllable way to produce MoS 2 films. High-quality MoS 2 thin films are most commonly deposited by chemical vapor deposition (CVD) or sulfurization of metal or metal oxide thin films. The most common Molybdenum disulfide (MoS 2 ) is a semiconducting 2D material, which has evoked wide interest due to its unique properties. However, the lack of controlled and scalable methods for the production of MoS 2 films at low temperatures remains a major hindrance on its way to applications. In this work, atomic layer deposition (ALD) is used to deposit crystalline MoS 2 thin films at a relatively low temperature of 300 °C. A new molybdenum precursor, Mo(thd) 3 (thd = 2,2,6,6-tetramethylheptane-3,5-dionato), is synthesized, characterized, and used for film deposition with H 2 S as the sulfur precursor. Self-limiting growth with a low growth rate of ≈0.025 Å cycle −1 , straightforward thickness control, and large-area uni...

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Section: Doi: 101002/admi201700123mentioning

confidence: 99%

Atomic Layer Deposition of Crystalline MoS₂ Thin Films: New Molybdenum Precursor for Low‐Temperature Film Growth

Mattinen

Hatanpää

Sarnet

et al. 2017

Adv Materials Inter

105

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“…[17][18][19] Secondly, chemical functionalisation to further tailor the materials' properties on demand is currently in its infancy. [20][21][22] With few exceptions, 23,24 the covalent chemistry is currently limited to CE-1T-TMDs, which are of less interest in optoelectronic applications due to its lack of visible optical absorption or emission. In addition to the functionalisation routes involving the addition of organic molecules, 20,21 it has been shown that CE-1T-TMDs react with AuCl 3 even in the absence of additional reducing agents.…”

Section: Introductionmentioning

confidence: 99%

“…[20][21][22] With few exceptions, 23,24 the covalent chemistry is currently limited to CE-1T-TMDs, which are of less interest in optoelectronic applications due to its lack of visible optical absorption or emission. In addition to the functionalisation routes involving the addition of organic molecules, 20,21 it has been shown that CE-1T-TMDs react with AuCl 3 even in the absence of additional reducing agents. [25][26][27][28] As a result, Au 0 is produced and nucleates to form Au nanoparticles (AuNPs).…”

Section: Introductionmentioning

confidence: 99%

Production of monolayer-rich gold-decorated 2H–WS2 nanosheets by defect engineering

et al. 2018

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Chemical functionalization of low-dimensional nanostructures has evolved as powerful tool to tailor the materials' properties on demand. For two-dimensional transition metal dichalcogenides, functionalization strategies are mostly limited to the metallic 1T-polytype with only few examples showing a successful derivatization of the semiconducting 2H-polytype. Here, we describe that liquid-exfoliated WS 2 undergoes a spontaneous redox reaction with AuCl 3 . We propose that thiol groups at edges and defects sites reduce the AuCl 3 to Au 0 and are in turn oxidized to disulfides. As a result of the reaction, Au nanoparticles nucleate predominantly at edges with tuneable nanoparticle size and density. The drastic changes in nanosheet mass obtained after high loading with Au nanoparticles can be exploited to enrich the dispersions in laterally large, monolayered nanosheets by simple centrifugation. The optical properties (for example photoluminescence) of the monolayers remain pristine, while the electrocatalytic activity towards the hydrogen evolution reaction is significantly improved.

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“…

biomedicine, [2,3] tribology, [4] photonics, [5] and electrocatalysis, [6] among others. [7] This progress has focused on the functionalization of mono-or few-layer nanosheets with lateral dimensions greater than 100 nm by combining chemical exfoliation, [8][9][10][11][12] micromechanical exfoliation, [13] or liquid exfoliation [14] with the reaction of functionalities. [7] This progress has focused on the functionalization of mono-or few-layer nanosheets with lateral dimensions greater than 100 nm by combining chemical exfoliation, [8][9][10][11][12] micromechanical exfoliation, [13] or liquid exfoliation [14] with the reaction of functionalities.

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mentioning

confidence: 99%

Simultaneous Fabrication and Functionalization of Nanoparticles of 2D Materials with Hybrid Optical Properties

Ibrahim

Irannejad

Wales

et al. 2018

Advanced Optical Materials

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biomedicine, [2,3] tribology, [4] photonics, [5] and electrocatalysis, [6] among others. Significant progress has been made recently in fabricating and functionalizing 2D nanosheets of transition metal dichalcogenides. [7] This progress has focused on the functionalization of mono-or few-layer nanosheets with lateral dimensions greater than 100 nm by combining chemical exfoliation, [8][9][10][11][12] micromechanical exfoliation, [13] or liquid exfoliation [14] with the reaction of functionalities. The formation and functionalization of smaller 2D nanoparticles or quantum dots, on the other hand, is still in its infancy.In what has been cited as the first direct evidence of covalent functionalization of a nanoscale transition metal dichalcogenide, Tuxen et al. produced MoS 2 monolayer nanoclusters in ultrahigh vacuum on a gold substrate and attached dibenzothiophene molecules to the clusters via controlled vapor exposure. [15,16] Beyond substrate-supported nanoclusters, the functionalization of nongraphene 2D nanoparticles suspended in solution was reported last year. Atkin et al. combined ultrasonication of WS 2 with microwave treatment in a citric acid-containing solution to produce monolayer WS 2 nanosheets ≈20-80 nm in diameter decorated with 2-5 nm carbon dots. [6] Jung et al. impinged BN flakes with super-heated nanoparticles then exposed them to water vapor to produce edge-hydroxylated BN quantum dots with 8 nm lateral size. [2] These techniques for fabricating and functionalizing 2D nanosheets and smaller nanoparticles are relatively slow (in some cases requiring several days), often require dangerous chemicals and elevated temperatures, and their demonstration has been material specific. In the case of functionalized 2D nanoparticles other than graphene, such as functionalized MoS 2 , WS 2 , and BN quantum dots, potentially exciting multifunctional optical properties have not been realized. The ability to produce a variety of hybrid 2D nanoparticles that possess the optical properties of both the host 2D material and functional groups would be extremely valuable for many of the aforementioned applications.We introduce a rapid femtosecond laser technique that simultaneously reduces the dimensions of flakes of 2D materials to a few nanometers and dissociates solvent molecules to bond with the edges of the freshly cleaved 2D sheets, in order to produce functionalized nanoparticles of 2D materials. Etha nol, a common and inexpensive solvent, is used to facilitate functionalization A general, rapid technique is introduced to simultaneously fabricate and functionalize nanoparticles of 2D materials. A femtosecond laser is used to irradiate flakes of 2D materials in an ethanol-containing solvent. The highly energetic laser pulses exfoliate and cleave the flakes into nanosheets with diameters of ≈3 nm and simultaneously dissociate the solvent molecules. The dissociated carbon and oxygen atoms bond with the freshly cleaved 2D nanoparticles to satisfy edge sites, resulting in the formation of hybrid 2D nanoparticles...

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Functionalization of Two‐Dimensional Transition‐Metal Dichalcogenides

Cited by 195 publications

References 49 publications

Atomic Layer Deposition of Crystalline MoS₂ Thin Films: New Molybdenum Precursor for Low‐Temperature Film Growth

Atomic Layer Deposition of Crystalline MoS₂ Thin Films: New Molybdenum Precursor for Low‐Temperature Film Growth

Production of monolayer-rich gold-decorated 2H–WS2 nanosheets by defect engineering

Simultaneous Fabrication and Functionalization of Nanoparticles of 2D Materials with Hybrid Optical Properties

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Functionalization of Two‐Dimensional Transition‐Metal Dichalcogenides

Cited by 195 publications

References 49 publications

Atomic Layer Deposition of Crystalline MoS2 Thin Films: New Molybdenum Precursor for Low‐Temperature Film Growth

Atomic Layer Deposition of Crystalline MoS2 Thin Films: New Molybdenum Precursor for Low‐Temperature Film Growth

Production of monolayer-rich gold-decorated 2H–WS2 nanosheets by defect engineering

Simultaneous Fabrication and Functionalization of Nanoparticles of 2D Materials with Hybrid Optical Properties

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Product

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Atomic Layer Deposition of Crystalline MoS₂ Thin Films: New Molybdenum Precursor for Low‐Temperature Film Growth

Atomic Layer Deposition of Crystalline MoS₂ Thin Films: New Molybdenum Precursor for Low‐Temperature Film Growth