Atom-resolved scanning tunneling microscopy investigations of molecular adsorption on MoS2 and CoMoS hydrodesulfurization catalysts

Lauritsen, Jeppe V.; Besenbacher, Flemming

doi:10.1016/j.jcat.2014.12.034

Cited by 113 publications

(73 citation statements)

References 75 publications

(121 reference statements)

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“…As such, an equivalent model of the promoted MoO 3 (010) surface corresponds to a system, in which all Mo atoms in the top layer are replaced by the promoter metal atoms. This model choice was adopted from prior work on MoS 2 without further stability considerations to allow for direct comparison of our results with the exhaustive theoretical work published for MoS 2 catalysts, and to confirm that design strategies can be translated from HDS to HDO catalysis …”

Section: Resultsmentioning

confidence: 97%

“…To study the effect of transition metal promotion of MoO 3 on oxygen vacancy formation, we chose a model system that closely resembles the MoS 2 case. Based on exhaustive literature evidence, it is known that Co and Ni substitute preferentially Mo atoms at the S edge . In fact, the most common catalyst models assume a complete substitution of Mo atoms with the promoter metal at the S edge .…”

Section: Resultsmentioning

confidence: 99%

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Learning from the past: Are catalyst design principles transferrable between hydrodesulfurization and deoxygenation?

Kasiraju

Grabow

2018

AIChE Journal

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Molybdenum-oxide (MoO 3 ) is a promising catalyst candidate for hydrodeoxygenation (HDO) of pyrolysis vapor or liquefaction products to renewable fuels or value-added chemicals. Density functional theory is used to study the mechanism and active site requirements for HDO of furan over the MoO 3 (010) facet and contrast our results with prior work on hydrodesulfurization (HDS) of thiophene over MoS 2 model catalysts. The potential energy diagram for HDO over a realistically terminated MoO 3 (010) surface facet reveals that the elementary reaction steps for deoxygenation are facile, but the formation of oxygen-vacancies is slow and endothermic. In general, HDO over MoO 3 and HDS over MoS 2 exhibit mechanistic similarities, which suggests that knowledge transfer from the mature HDS system to the emerging field of HDO catalysis is possible. For example, transition metal promotion of MoO 3 resulted in an improvement of the kinetics and thermodynamics of oxygen vacancy formation, similar to Co and Ni promotion of MoS 2 . V C 2018 American Institute of Chemical Engineers AIChE J, 00: 000-000, 2018

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Learning from the past: Are catalyst design principles transferrable between hydrodesulfurization and deoxygenation?

Kasiraju

Grabow

2018

AIChE Journal

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“…[64] The edges of basal plane-terminated, typically plate-like crystallites, on the other hand, contain dangling bonds and may act as reactive sites, as may also other kinds of defect sites. Thus, it is possible that the film growth proceeds mainly on the edges and defects, which could explain the slow growth.…”

Section: Wwwadvmatinterfacesdementioning

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

111

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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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“…While the edge sites of MoS 2 show high activity for the HER, the basal plane of the room‐temperature stable 2H‐phase MoS 2 is catalytically inert . Several strategies have been proposed to enhance the activity of MoS 2 , including preparing nanostructures, enhancing defect concentration, introducing a degree of disorder and oxygen incorporation, and doping with transition metal atoms, such as Pt at the 1–2% level . Among those efforts, it has been shown that alkaline metal intercalation can transform MoS 2 into a metallic tetragonal phase (T‐phase) in which the basal plane becomes active for hydrogen production .…”

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confidence: 99%

Rhenium‐Doped and Stabilized MoS₂ Atomic Layers with Basal‐Plane Catalytic Activity

et al. 2018

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The development of stable and efficient hydrogen evolution reaction (HER) catalysts is essential for the production of hydrogen as a clean energy resource. A combination of experiment and theory demonstrates that the normally inert basal planes of 2D layers of MoS2 can be made highly catalytically active for the HER when alloyed with rhenium (Re). The presence of Re at the ≈50% level converts the material to a stable distorted tetragonal (DT) structure that shows enhanced HER activity as compared to most of the MoS2‐based catalysts reported in the literature. More importantly, this new alloy catalyst shows much better stability over time and cycling than lithiated 1T‐MoS2. Density functional theory calculations find that the role of Re is only to stabilize the DT structure, while catalysis occurs primarily in local Mo‐rich DT configurations, where the HER catalytic activity is very close to that in Pt. The study provides a new strategy to improve the overall HER performance of MoS2‐based materials via chemical doping.

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Atom-resolved scanning tunneling microscopy investigations of molecular adsorption on MoS2 and CoMoS hydrodesulfurization catalysts

Cited by 113 publications

References 75 publications

Learning from the past: Are catalyst design principles transferrable between hydrodesulfurization and deoxygenation?

Learning from the past: Are catalyst design principles transferrable between hydrodesulfurization and deoxygenation?

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

Rhenium‐Doped and Stabilized MoS₂ Atomic Layers with Basal‐Plane Catalytic Activity

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Atom-resolved scanning tunneling microscopy investigations of molecular adsorption on MoS2 and CoMoS hydrodesulfurization catalysts

Cited by 113 publications

References 75 publications

Learning from the past: Are catalyst design principles transferrable between hydrodesulfurization and deoxygenation?

Learning from the past: Are catalyst design principles transferrable between hydrodesulfurization and deoxygenation?

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

Rhenium‐Doped and Stabilized MoS2 Atomic Layers with Basal‐Plane Catalytic Activity

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

Rhenium‐Doped and Stabilized MoS₂ Atomic Layers with Basal‐Plane Catalytic Activity