X-ray Photoelectron Spectroscopy Surface Quantification of Sulfided CoMoP Catalysts – Relation Between Activity and Promoted Sites – Part I: Influence of the Co/Mo Ratio

Gandubert, A. D.; Legens, C.; Denis, Guillaume; Rebours, S.; Payen, Edmond

doi:10.2516/ogst:2007007

Cited by 103 publications

(55 citation statements)

References 12 publications

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“…XPS profile of Co 2p shows a peak at binding energy of 778.7 which is suggestive for the presence of Co in Co x W (1− x ) S 2 . This value is very close to the one reported for Co 2p in CoWSx, CoMoP, or CoMoS phases . Here also, the absence of any cobalt sulfide phase, like Co 9 S 8 , can be substantiated as there is no peak corresponding to Co (at 778.1 ± 0.1 eV) for our case.…”

Section: Resultssupporting

confidence: 90%

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Engineering the Electronic Structure of 2D WS₂Nanosheets Using Co Incorporation as Co_xW_(1-_x₎S₂for Conspicuously Enhanced Hydrogen Generation

Shifa

Wang

Liu

et al. 2016

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Transition metal dichalcogenides (TMDs), as one of potential electrocatalysts for hydrogen evolution reaction (HER), have been extensively studied. Such TMD-based ternary materials are believed to engender optimization of hydrogen adsorption free energy to thermoneutral value. Theoretically, cobalt is predicted to actively promote the catalytic activity of WS2 . However, experimentally it requires systematic approach to form Cox W(1- x ) S2 without any concomitant side phases that are detrimental for the intended purpose. This study reports a rational method to synthesize pure ternary Cox W(1- x ) S2 nanosheets for efficiently catalyzing HER. Benefiting from the modification in the electronic structure, the resultant material requires overpotential of 121 mV versus reversible hydrogen electrode (RHE) to achieve current density of 10 mA cm(-2) and shows Tafel slope of 67 mV dec(-1) . Furthermore, negligible loss of activity is observed over continues electrolysis of up to 2 h demonstrating its fair stability. The finding provides noticeable experimental support for other computational reports and paves the way for further works in the area of HER catalysis based on ternary materials.

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Section: Resultssupporting

confidence: 90%

“…Comparison of the fabricated Co x W (1− x ) S 2 nanosheet with the state‐of‐the‐art HER electrocatalysts in terms of Tafel slope and the overpotential required to achieve current density of 10 mA cm −2 . Data from references …”

Section: Resultsmentioning

confidence: 99%

Engineering the Electronic Structure of 2D WS₂Nanosheets Using Co Incorporation as Co_xW_(1-_x₎S₂for Conspicuously Enhanced Hydrogen Generation

Shifa

Wang

Liu

et al. 2016

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“…On inset b) corresponding to the intermediate Δμ S , the Co/Mo ratio is 0.29 which is very close to the optimal ratio required for catalytic activity [72,73]. In this case, it can be noticed that the number of mixed CoMo sites per crystallite is equal to 9 (including M-edge and corner sites).…”

Section: Nano-crystallite Morphologiesmentioning

confidence: 53%

A DFT Study of CoMoS and NiMoS Catalysts: from Nano-Crystallite Morphology to Selective Hydrodesulfurization

Krebs

Daudin²,

Raybaud³

2009

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Étude DFT des catalyseurs CoMoS et NiMoS : de la morphologie des nano-cristallites à l'hydrodésulfuration sélective -Cet article présente des résultats récents obtenus dans des études utilisant la théorie de la fonctionnelle de la densité (DFT) pour la caractérisation à l'échelle atomique des phases actives Co(Ni)MoS utilisées en catalyse d'hydrodésulfuration (HDS) sélective. L'effet des conditions du milieu réactionnel sulfo-réducteur sur la stabilité et la nature des sites actifs localisés au bord des nano-cristallites Co(Ni)MoS est mis en évidence. En combinant les calculs DFT et un modèle thermodynamique, il apparaît que la teneur en promoteur sur les bords des cristallites en conjonction avec la morphologie des cristallites dépend des conditions sulfo-réductrices. Nous montrons ensuite comment la nature des sites actifs Co(Ni)Mo influence l'HDS sélective de molécules soufrées légères (alkylthiophènes) vis-à-vis de l'hydrogénation (HydO) des oléfines légères (alkyl-butènes). La combinaison des calculs DFT d'adsorption de deux molécules modèles (2-méthyl-thiophène et 2,3-diméthyl-but-1-ène) avec la modélisation cinétique de la sélectivité HDS/HydO permet de proposer une explication de l'origine de cette sélectivité basée sur la compétition d'adsorption des réactifs. Abstract -A DFT Study of CoMoS and NiMoS Catalysts from Nano-Crystallite Morphology to Selective Hydrodesulfurization -This paper reports an overview of recent DFT studies on the atomic scale characterization of Co(Ni)MoS active phases used in selective hydrodesulfurization (HDS) catalysis. A peculiar attention is paid to the effect of the sulfo-reductive reaction conditions on the

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“…7(a) illustrates a broad scan XPS spectrum (from 0 to 1100 eV) of different spheres, which again conrms the elements of iron, cobalt and oxygen, similar to the EDS analysis. 39 The Co2p 3/2 satellite conrms the cobaltous ion, excluding the possibility of a trivalence state. 7(b) and (c).…”

Section: Xps Determination Of Cation Sites and Discussionmentioning

confidence: 99%

Solvothermal synthesis of Co_xFe_3−xO₄ spheres and their microwave absorption properties

et al. 2014

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Co x Fe 3Àx O 4 (x ¼ 0-1) spheres are synthesized via a solvothermal reaction using ethylene glycol (EG) as a solvent. They are characterized, and the results show that the prepared spheres are mainly 300-500 nm in diameter and constituted by small grains. For the EG solution containing stoichiometric ingredients (atomic ratio of Co 2+ : Fe 3+ ¼ 1 : 2), the obtained spheres are Co 0.9 Fe 2.1 O 4 at 200 C (sphere A) andCo 0.74 Fe 2.26 O 4 (sphere B) at 300 C, whose crystallites are 23 nm and 30 nm in size, respectively. VSM measurements reveal improved properties with sphere B. Variations of complex permittivity and permeability for different composite (75% mass ratio of spheres) have been studied as a function of frequency. The calculated reflectivity value indicates that the composite containing sphere A displays better microwave absorption capability. The minimum reflection loss reaches À41.089 dB at 12.08 GHz, with a matching thickness of 2 mm. The dielectric loss contributes even more than magnetic loss in the frequency range of 3-14 GHz. The synergistic effect of dual losses makes the submicrosphere a promising absorbent in X and Ku bands. The composite consisting of sphere B is inferior in dielectric properties owing to ferrous ion migration from octahedral to tetrahedral sites and due to the big crystallites lacking defects. After the calcination treatment of the spheres at 700 C, the dielectric loss turns out to be low due to the disappearing Fe 2+ 4 Fe 3+ pairs in adjacent octahedral sites and the loss of defects. Variations of the cobalt ratio in spheres can change the resonance frequency and crystallinity of the spheres and ultimately the minimum reflection loss and corresponding frequency band. The microwave absorption properties of mixed magnetite and cobalt ferrite spheres are influenced by the cationic stoichiometry and crystalline integrity.

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X-ray Photoelectron Spectroscopy Surface Quantification of Sulfided CoMoP Catalysts – Relation Between Activity and Promoted Sites – Part I: Influence of the Co/Mo Ratio

Cited by 103 publications

References 12 publications

Engineering the Electronic Structure of 2D WS₂Nanosheets Using Co Incorporation as Co_xW_(1-_x₎S₂for Conspicuously Enhanced Hydrogen Generation

Engineering the Electronic Structure of 2D WS₂Nanosheets Using Co Incorporation as Co_xW_(1-_x₎S₂for Conspicuously Enhanced Hydrogen Generation

A DFT Study of CoMoS and NiMoS Catalysts: from Nano-Crystallite Morphology to Selective Hydrodesulfurization

Solvothermal synthesis of Co_xFe_3−xO₄ spheres and their microwave absorption properties

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X-ray Photoelectron Spectroscopy Surface Quantification of Sulfided CoMoP Catalysts – Relation Between Activity and Promoted Sites – Part I: Influence of the Co/Mo Ratio

Cited by 103 publications

References 12 publications

Engineering the Electronic Structure of 2D WS2Nanosheets Using Co Incorporation as CoxW(1-x)S2for Conspicuously Enhanced Hydrogen Generation

Engineering the Electronic Structure of 2D WS2Nanosheets Using Co Incorporation as CoxW(1-x)S2for Conspicuously Enhanced Hydrogen Generation

A DFT Study of CoMoS and NiMoS Catalysts: from Nano-Crystallite Morphology to Selective Hydrodesulfurization

Solvothermal synthesis of CoxFe3−xO4 spheres and their microwave absorption properties

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Engineering the Electronic Structure of 2D WS₂Nanosheets Using Co Incorporation as Co_xW_(1-_x₎S₂for Conspicuously Enhanced Hydrogen Generation

Engineering the Electronic Structure of 2D WS₂Nanosheets Using Co Incorporation as Co_xW_(1-_x₎S₂for Conspicuously Enhanced Hydrogen Generation

Solvothermal synthesis of Co_xFe_3−xO₄ spheres and their microwave absorption properties