Size-dependent structure of MoS2 nanocrystals

Lauritsen, Jeppe V.; Kibsgaard, Jakob; Helveg, Stig; Topsøe, Henrik; Clausen, Bjerne S.; Lægsgaard, Erik; Besenbacher, Flemming

doi:10.1038/nnano.2006.171

Cited by 676 publications

(732 citation statements)

References 35 publications

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“…This edge configuration is particularly interesting because the metallic edge state on the S 2 dimers supports a strong 1D edge plasmon [19]. Depending on the growth conditions, the flakes favor different edge terminations or shapes [16,[25][26][27]. However, for alternative S-terminated edges, the 1D plasmons are expected to couple weaker to light [19] and they have not been reported in previous computational studies of Sterminated triangular flakes [28,29].…”

Section: Introductionmentioning

confidence: 90%

Effect of edge plasmons on the optical properties of MoS2 monolayer flakes

et al. 2017

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Finite MoS 2 nanoparticles are known to support metallic edge states that are responsible for their catalytic activity. In this work we employ time-dependent density-functional theory (TDDFT) to study the influence of such edge states on the optical properties of triangular MoS 2 monolayer flakes. We find that the edge states support collective plasmon-like excitations that couple strongly to the optical field leading to pronounced absorption peaks below the onset of interband transitions on the basal plane. Additionally, structural relaxation of the flakes can significantly distort the edge states. Thus, we observe that while an evenly-spaced edge configuration supports one-dimensional (1D) plasmon modes similar to those of an ideal 1D electron gas, the relaxed structures show mixed plasmon and single-electron excitations in the low-energy response. Our findings illustrate the sensitivity of the optical response of MoS 2 nanostructures to the details of the edge configuration.

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Section: Introductionmentioning

confidence: 90%

Effect of edge plasmons on the optical properties of MoS2 monolayer flakes

et al. 2017

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Section: Edges As Active Sitesmentioning

confidence: 99%

“…Not to our surprise, the structures of MoS 2 with different sizes are not exact the same, they possess different Mo or S edge coverage. A rearrangement of the S atoms at edges would influence bonding strength of Mo‐S, thus changes the stability and catalytic activity 42. Another phase of MoS 2 is called 1T phase, which is constructed by edge‐sharing MoS 6 octahedra.…”

Section: Edges As Active Sitesmentioning

confidence: 99%

Face the Edges: Catalytic Active Sites of Nanomaterials

Wang

2015

Advanced Science

158

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Edges are special sites in nanomaterials. The atoms residing on the edges have different environments compared to those in other parts of a nanomaterial and, therefore, they may have different properties. Here, recent progress in nanomaterial fields is summarized from the viewpoint of the edges. Typically, edge sites in MoS2 or metals, other than surface atoms, can perform as active centers for catalytic reactions, so the method to enhance performance lies in the optimization of the edge structures. The edges of multicomponent interfaces present even more possibilities to enhance the activities of nanomaterials. Nanoframes and ultrathin nanowires have similarities to conventional edges of nanoparticles, the application of which as catalysts can help to reduce the use of costly materials. Looking beyond this, the edge structures of graphene are also essential for their properties. In short, the edge structure can influence many properties of materials.

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“…This group of catalysts is already industrially established for hydrodesulfurization (HDS) of crude oil [15][16][17][18]. In HDS, the activity of the catalyst has been linked to the availability of edge sites on the MoS2 slabs with two adsorption sites for the sulfur containing compound on vacancy sites and hydrogen on Mo-S [16,[19][20][21][22]. As the mechanisms for HDS and HDO are similar, this type of sites are believed to be the active sites for HDO as well [23,24].…”

Section: Introductionmentioning

confidence: 99%

Deactivation of Ni-MoS2 by bio-oil impurities during hydrodeoxygenation of phenol and octanol

Mortensen

Gardini

Damsgaard

et al. 2016

Applied Catalysis A: General

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Deactivation of Ni-MoS2 by bio-oil impurities during hydrodeoxygenation of phenol and octanol, Applied Catalysis A, General http://dx.doi.org/10. 1016/j.apcata.2016.06.002 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Graphical abstractHighlights  Impurities as Cl, S, and K found in bio-oil will deactivate or inhibit MoS2-type catalyst by competing for the active sites  MoS2-based catalysts will produce sulfur containing hydrocarbons during HDO, but these can be removed again if a sufficiently high residence time is used enabling desulfurization of the product  Chlorine binds more strongly to the active sites of MoS2 based catalysts compared to H2O and H2S, while K irreversibly deactivates the catalyst 3 AbstractThe stability of Ni-MoS2/ZrO2 toward water, potassium, and chlorine containing compounds during hydrodeoxygenation (HDO) of a mixture of phenol and 1-octanol was investigated in a high pressure gas and liquid continuous flow fixed bed setup at 280°C and 100 bar. To maintain the stability of the catalyst, sufficient co-feeding of a sulfur source was necessary to avoid oxidation of the sulfide phase by oxygen replacement of the edge sulfur atoms in the MoS2 structure. However, the addition of sulfur to the feed gas resulted in the formation of sulfur containing compounds, mainly thiols, in the oil product if the residence time was too low. At a weight hourly space velocity (WHSV) of 4.9 h -1 the sulfur content in the liquid product was 980 ppm by weight, but this could be decreased to 5 ppm at a WHSV of 1.4 h -1 . A high co-feed of sulfur was needed when water was present in the feed and the H2O/H2S molar ratio should be below ca. 10 to maintain a decent stability of the catalyst. Chlorine containing compounds caused a reversible deactivation of the catalyst when co-fed to the reactor, where the catalytic activity could be completely regained when removing it from the feed. Commonly, chlorine, H2O, and H2S all inhibited the activity of the catalyst by competing for the active sites, with chlorine being by far the strongest inhibitor and H2S and H2O of roughly the same strength. Dissimilar, potassium was a severe poison and irreversibly deactivated the catalyst to <5% degree of deoxygenation when impregnated on the catalyst in a stoichiometric ratio relative to the active metal. This deactivation was a result of adsorption of potassium on the edge vacancy sites of the MoS2 slabs.

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Size-dependent structure of MoS2 nanocrystals

Cited by 676 publications

References 35 publications

Effect of edge plasmons on the optical properties of MoS2 monolayer flakes

Effect of edge plasmons on the optical properties of MoS2 monolayer flakes

Face the Edges: Catalytic Active Sites of Nanomaterials

Deactivation of Ni-MoS2 by bio-oil impurities during hydrodeoxygenation of phenol and octanol

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