Methoxy Formation Induced Defects on MoS<sub>2</sub>

Evans, Prescott E.; Jeong, Hae Kyung; Hooshmand, Zahra; Le, Duy; Rawal, Takat B.; Alvillar, Sahar Naghibi; Bartels, Ludwig; Rahman, Talat S.

doi:10.1021/acs.jpcc.8b02053

Cited by 10 publications

(7 citation statements)

References 57 publications

(91 reference statements)

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“…The deconvolution and peak fitting of the C 1s spectra during CH 3 OH dosing [Figure 1c] reveal the presence of the CH 3 O peak at 285.7 eV. 52,53 The CH 3 O formation is also confirmed from the weak peak at 530. ) may be present in small amounts as an intermediate product in dehydrogenation, its easy desorption to the gas phase (due to its small adsorption energy on the Cu surface) 18 makes it undetectable at low pressure.…”

Section: Methodsmentioning

confidence: 93%

Effect of the Chemical States of Copper on Methanol Decomposition and Oxidation

Wang,

Li,

Zhu

et al. 2024

J. Phys. Chem. C

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The decomposition and oxidation reactions of CH 3 OH over metallic Cu(100) and Cu 2 O-covered Cu(100) surfaces are studied by using a combination of in situ ambientpressure X-ray photoelectron spectroscopy, Auger electron spectroscopy, and density functional theory calculations. We identify the sequential chemical transformation pathways from bond cleavage to the formation of intermediates and final products under operational conditions. Accumulative surface adsorption of CH 3 O species on metallic Cu( 100) impedes the decomposition of CH 3 OH. Co-dosing on metallic Cu(100) with low pressures of 1 × 10 −4 Torr CH 3 OH + 1 × 10 −4 Torr O 2 results in partial oxidation of CH 3 OH, where the chemisorbed O ads reduces surface sites available for CH 3 O adsorption, decreasing the surface activity for CH 3 OH decomposition. In contrast, the Cu 2 O overlayer formed under the elevated pressures of 0.33 Torr CH 3 OH + 0.66 Torr O 2 promotes the total oxidation of CH 3 OH into the final products of CO 2 and H 2 O, arising from the active reaction between lattice O within Cu 2 O and intermediates of CH 3 O, CH 2 O, HCOO, and CO. Despite the more favorable O−H bond scission, C−O bond scission also occurs to result in surface accumulation of CH x on metallic Cu(100), blocking active sites for decomposition reactions of CH 3 OH and CH 3 O. By comparison, the CH x species on the Cu 2 O-covered Cu(100) undergo oxidation into CO 2 and H 2 O with lattice O in the Cu 2 O overlayer, thereby freeing active sites for the total oxidation of CH 3 OH. These results highlight the distinct roles of metallic Cu and Cu 2 O in the pathways of CH 3 OH decomposition and oxidation reactions, offering practical insights for the design of Cu-based catalysts with tailored reactivity and selectivity.

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Section: Methodsmentioning

confidence: 93%

Effect of the Chemical States of Copper on Methanol Decomposition and Oxidation

Wang,

Li,

Zhu

et al. 2024

J. Phys. Chem. C

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“…For instance, it has been shown that the exposure of MoS 2 to methanol (e.g., in a water/methanol system) can lead to the formation of sulfur vacancies. [120] The Li-intercalation-exfoliation is the other main type of exfoliation method for the production of TMDs, in which their parent crystals are immersed in a solution containing lithium ions such as hexyllithium or n-butyllithium under inert and dry conditions for a few days. During this process, Li intercalates into the interlayer spaces of TMDs and reacts to form compositions such as Li x MX 2 .…”

Section: Transition Metal Dichalcogenides (Tmds)mentioning

confidence: 99%

“…[ 119 ] However, due to their significantly higher exfoliation energy (surface energy), [ 98 ] delamination of the TMDs is more difficult than graphene, which is a big challenge for the production of high concentration suspensions and ink formulation. Since the exfoliation method (e.g., the dispersion medium) can drastically affect the chemical/structural properties of the TMDs (will be discussed later), [ 120 ] and hence their performance, the exfoliation/synthesis of the 2D TMDs requires further attention. Therefore, before discussing the printing/coating of this group of 2D materials, their LPE, which is usually the starting point for ink formulation, will be briefly reviewed.…”

Section: Semiconductive Inksmentioning

confidence: 99%

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Functional Ink Formulation for Printing and Coating of Graphene and Other 2D Materials: Challenges and Solutions

et al. 2022

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The properties of 2D materials are unparalleled when compared to their 3D counterparts; many of these properties are a consequence of their size reduction to only a couple of atomic layers. Metallic, semiconducting, and insulating types can be found and form a platform for a new generation of devices. Among the possible methods to utilize 2D materials, functional printing has emerged as a strong contender because inks can be directly formulated from dispersions obtained by liquid‐phase exfoliation. Printed graphene‐based devices are shifting from laboratory applications toward real‐world and mass‐producible systems going hand in hand with a good understanding of suitable exfoliation methods for the targeted type of ink. Such a clear picture does not yet exist for hexagonal boron nitride (h‐BN), the transition metal dichalcogenides (TMDs), and black phosphorous (BP). Rather, reports of applications of these 2D materials in printed devices are scattered throughout the literature, not yet adding to a comprehensive and full understanding of the relevant parameters. This perspective starts with a summary of the most important features of inks from exfoliated graphene. For h‐BN, the TMDs, and BP, the characteristic properties when exfoliated from solution and strategies to formulate inks are summarized.

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“…11 It therefore calls for prudent ways to activate the basal plane of h-BN. Taking cues from prior studies on MoS 2 , [12][13][14][15][16][17] proposals have been made to activate the basal plane on h-BN by the creation of defects, 18,19 deposition of metal atoms or molecules, [20][21][22][23] creation of grain-boundaries, 24 and application of strain to the defective surface. 25 Quite akin to defect-laden single-layer MoS 2 (with sulfur vacancies), which calculations predict to be a possible catalyst for hydrogenation of syngas to alcohol, 12 the basal plane of the single-layer h-BN can be chemically activated for similar reaction, in the presence of point or line defects on the surface.…”

Section: Introductionmentioning

confidence: 99%