Modeling the Structure of Amorphous MoS<sub>3</sub>: A Neutron Diffraction and Reverse Monte Carlo Study.

Hibble, Simon J.; Wood, Glenn B.

doi:10.1002/chin.200415002

Cited by 3 publications

(3 citation statements)

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“…Thus, when acidified, thiomolybdates produce a brown amorphous MoS 3 compound which is stable in mineral acids. 7,59,60 In the same lines, MoS 2 is stable in reasonably concentrated acids (e.g., in 0.5 M H 2 SO 4 , extensively used to study its electrocatalytic properties 6,8 ). On the other hand, there are no known Mo(V) or Mo(VI) stable sulfates and therefore the Mo−O−S bond is easily hydrolyzed.…”

Section: Overall Oxidation Kinetics and Mechanisticmentioning

confidence: 97%

Oxidation of Nanodispersed MoS₂ in Ambient Air: The Products and the Mechanistic Steps

Afanasiev

Lorentz

2019

J. Phys. Chem. C

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Oxidation of finely divided molybdenum sulfide in ambient air has been studied for air exposure times from 10 min to 1 year to clarify the nature of the reaction products and the mechanistic steps. At the initial steps, for air exposure times from several minutes to several hours, rapid oxidation of MoS 2 edges occurs with simultaneous formation of hydroxyl species and surface disulfide S 2 2− moieties as attested by 1 H NMR, X-ray photoelectron spectra, and temperature-programmed reduction. Prolonged air exposure of MoS 2 nanodispersions leads to deep oxidation. According to the results of X-ray absorption spectroscopy, UV−visible, and electron paramagnetic resonance spectroscopies, the main oxidation products are soluble paramagnetic molybdenum blue species and sulfuric acid. As shown by EXAS fitting, the major product is oxo-bridged dimolybdenyl Mo(V, VI) species. Ambient moisture plays an important role in the oxidation process as it contributes to the formation of sulfuric acid which leads to liquescence of the material and to deep oxidation without formation of a protective passivation layer.

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Section: Overall Oxidation Kinetics and Mechanisticmentioning

confidence: 97%

Oxidation of Nanodispersed MoS₂ in Ambient Air: The Products and the Mechanistic Steps

Afanasiev

Lorentz

2019

J. Phys. Chem. C

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“…The lower Tafel slope of MoS 3 in general (compared to bulk MoS 2 ) could also attribute to its amorphous nature. 3,4 It was discussed by Chia et al that the electrochemical process can result in the presence of a higher amorphous phase of the material. 35 A detailed study by Li et al exploring the relationship between the crystallinity and Tafel slope also reported lower Tafel slopes for the material with correspondingly lower crystallinity.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The structure of MoS 3 is still debatable with literatures citing either Mo 5+ (S 2 2− ) 0.5 (S 2− ) 2 or Mo 4+ (S 2 2− )(S 2− ). 4,24,26,28,30,38 From Tables 1 and 2, it is apparent that the increase in Mo 4+ is likely due to a reduction of Mo (A) . Less informative is the S spectra as it is hard to distinguish terminal S 2 2− from unsaturated S 2− at the lower binding energy and between the bridging S 2 2− and apical S 2at the higher BE because of their similar BE.…”

Section: Acs Omegamentioning

confidence: 99%

Molybdenum Sulfide Electrocatalysis is Dramatically Influenced by Solvents Used for Its Dispersions

Chua¹,

Pumera

2018

ACS Omega

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Transition metal dichalcogenides, especially MoS 2 and related MoS 3 , have attracted attention as potential replacement of platinum for electrochemical energy applications. These materials are typically treated before the use in solvents. It is assumed that these solvents do not influence follow-up electrochemistry. Here, we show that the oxygen reduction overpotentials as well as inherent electrochemistry of MoS 3 is dramatically influenced by solvents used, them being water, acetonitrile, dimethylformamide, or ethanol. This has a profound impact on the interpretation of the electrochemical studies and the choice of MoS x solvent treatment.

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Amorphous MoS2 from a machine learning inter-atomic potential

Kety,

Namsrai,

Nawaz

et al. 2024

The Journal of Chemical Physics

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Amorphous molybdenum disulfide has shown potential as a hydrogen evolution catalyst, but the origin of its high activity is unclear, as is its atomic structure. Here, we have developed a classical inter-atomic potential using the charge equilibration neural network method, and we have employed it to generate atomic models of amorphous MoS2 by melting and quenching processes. The amorphous phase contains an abundance of molybdenum and sulfur atoms in low coordination. Besides the 6-coordinated molybdenum typical of the crystalline phases, a substantial fraction displays coordinations 4 and 5. The amorphous phase is also characterized by the appearance of direct S–S bonds. Density functional theory shows that the amorphous phase is metallic, with a considerable contribution of the 4-coordinated molybdenum to the density of states at the Fermi level. S–S bonds are related to the reduction of sulfur, with the excess electrons spread over several molybdenum atoms. Moreover, S–S bond formation is associated with a distinctive broadening of the 3s states, which could be exploited for experimental characterization of the amorphous phases. The large variety of local environments and the high density of electronic states at the Fermi level may play a positive role in increasing the electrocatalytic activity of this compound.

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Modeling the Structure of Amorphous MoS₃: A Neutron Diffraction and Reverse Monte Carlo Study.

Cited by 3 publications

References 1 publication

Oxidation of Nanodispersed MoS₂ in Ambient Air: The Products and the Mechanistic Steps

Oxidation of Nanodispersed MoS₂ in Ambient Air: The Products and the Mechanistic Steps

Molybdenum Sulfide Electrocatalysis is Dramatically Influenced by Solvents Used for Its Dispersions

Amorphous MoS2 from a machine learning inter-atomic potential

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Modeling the Structure of Amorphous MoS3: A Neutron Diffraction and Reverse Monte Carlo Study.

Cited by 3 publications

References 1 publication

Oxidation of Nanodispersed MoS2 in Ambient Air: The Products and the Mechanistic Steps

Oxidation of Nanodispersed MoS2 in Ambient Air: The Products and the Mechanistic Steps

Molybdenum Sulfide Electrocatalysis is Dramatically Influenced by Solvents Used for Its Dispersions

Amorphous MoS2 from a machine learning inter-atomic potential

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Modeling the Structure of Amorphous MoS₃: A Neutron Diffraction and Reverse Monte Carlo Study.

Oxidation of Nanodispersed MoS₂ in Ambient Air: The Products and the Mechanistic Steps

Oxidation of Nanodispersed MoS₂ in Ambient Air: The Products and the Mechanistic Steps