Highly Active Nonpromoted Hydrotreating Catalysts through the Controlled Growth of a Supported Hexagonal WS<sub>2</sub> Phase

Alphazan, Thibault; Bonduelle‐Skrzypczak, Audrey; Legens, C.; Boudene, Zoubeyr; Gîrleanu, Maria; Ersen, Ovidiu; Copéret, Christophe; Raybaud, Pascal

doi:10.1021/cs501311m

Cited by 40 publications

(46 citation statements)

References 79 publications

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“…3f, The four strong peaks at 34.8 eV, 35.4 eV, 36.7 eV and 37.4 eV can be indexed as W 4+ 4f and W 6+ 4f. 32 The decomposition of the W 4f spectrum shows that the incorporation of tungsten element. This is consistent with the previous results.…”

Section: Momentioning

confidence: 99%

3D Tungsten-Doped MoS₂Nanostructure: A Low-Cost, Facile Prepared Catalyst for Hydrogen Evolution Reaction

Liang

Mao

et al. 2016

J. Electrochem. Soc.

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Cost effective electrocatalysts for hydrogen evolution reactions are attractive for energy conversion and storage progress. A high performance hydrogen evolution reaction (HER) electrocatalyst of 3D MoS 2 nanostructure modified by tungsten incorporation is produced via hydrothermal method. By means of controllable tungsten incorporation, an optimized catalyst with rich defects was developed, exhibiting high hydrogen evolution activities. In general, the 3D MoS 2 -W3 exhibits an overpotential as low as 200 mV, accompanied with high exchange current density of 6.9 μA cm −2 and excellent stability after 3000 cycles. This work paves a new route in the design of efficient and durable non-precious-metal electrocatalysts for HER in acidic medium. Sustainable hydrogen production has attracted growing attention, and an advanced catalyst for the electrochemical hydrogen evolution reaction (HER) that results in increased efficiency of this important electrochemical process is urgently required.1-3 Although excellent HER performance has been reached for platinum and other precious metals, 4 replacing the expensive and rare catalysts with cost effective and high efficient alternatives still attract scientists' attention toward making the hydrogen production more economic and competitive. [5][6][7] During the past few years, transitional metal sulfides such as nanometer-scaled MoS 2 and WS 2 have attracted considerable attention in HER fields because of their low cost, high chemical stability, and excellent electrocatalytic properties. [8][9][10][11][12][13] Studies concluded that the unsaturated sulfur atoms on the edges of the 2D MoS 2 layers play a crucial role in HER catalysis 14 and the electric conductivity of catalysts is another crucial factor to affect the electrocatalytic activity. [15][16][17] Hence, increasing the number of active sites is an efficient pathway to enhance the HER activity. 18,19 The latest reported results show a new strategy to fabricate a new oxygen-incorporated MoS 2 ultrathin nanosheets catalyst that preferentially exposes active sites by incorporating oxygen atoms.20 Zhou et al. prepared ultrathin MoS 2(1−x) Se 2x alloy nanoflakes with monolayer or few-layer thickness, which possessed more active sites than single MoS 2 .21 Rao et al. studied rhenium-doped nanoparticles of MoS 2 with fullerene-like structures (IF-MoS 2 ), that not only changes the intrinsic nature of the MoS 2 but also increases its reactivity. 22Cationic doping with a small fraction of cobalt or nickel is also used to promote the electrocatalytic performance of MoS 2 . Besides, Ni, Co and Fe were adopted to improve the intrinsic activity, and more highly conductive materials were added to improve the electrical contact, including graphene, carbon nanotubes, carbon nanospheres, and so on. [23][24][25] With respect to the last issue, the structure design of MoS 2 has attracted great attentions to obtain more active sites. 26 Both of WS 2 and MoS 2 are transition-metal sulfides, which have the similar crystal structure. Moreover...

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Section: Momentioning

confidence: 99%

3D Tungsten-Doped MoS₂Nanostructure: A Low-Cost, Facile Prepared Catalyst for Hydrogen Evolution Reaction

Liang

Mao

et al. 2016

J. Electrochem. Soc.

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“…Sulfide model catalysts have also been analyzed by HR HAADF-STEM in order to confirm the orientation of MoS 2 slabs determined by GI-EXAFS. In fact, with STEM in the HAADF detection mode, intensity is proportional to the squared atomic number (Z²) of the observed atoms [54,55], making feasible the detection of MoS 2 slabs oriented perpendicular to the incident electron beam and thus parallel to the surface and possibly the determination of the associated 2D morphology [56][57][58][59]. The analysis was also performed on samples sulfided at 300 °C to compare HAADF-STEM images to GI-EXAFS results.…”

Section: Support Effect On the Orientation Of Mos 2 Slabsmentioning

confidence: 99%

Surface-dependent sulfidation and orientation of MoS2 slabs on alumina-supported model hydrodesulfurization catalysts

Bara

Lamic‐Humblot

Fonda

et al. 2016

Journal of Catalysis

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The constant improvement of hydrotreating (HDT) catalysts, driven by industrial and environmental needs, requires a better understanding of the interactions between the oxide support (mostly alumina) and the MoS 2 active phase. Hence, this work addresses the supportdependent genesis of MoS 2 on four planar, single crystal -Al 2 O 3 surfaces with different crystal orientations (C (0001), R , M and A). In contrast to classical surface science techniques, which often rely on UHV-type deposition methods, the Mo is introduced by impregnation from an aqueous solution, in order to mimic the standard incipient wetness impregnation. Comparison between different preparation routes, impregnation vs. equilibrium adsorption (selective adsorption), is also considered. AFM, XAS, TEM and XPS show that the -Al 2 O 3 orientation has a clear impact on the strength of metal-support interactions at the oxide state with consequences on the sulfidation, size, stacking and orientation of MoS 2 slabs. Aggregation of molybdenum oxide particles is observed on the C (0001) plane suggesting weak metal-support interactions leading to high sulfidation degree with large slabs. Conversely, the presence of well-dispersed individual oxide particles on the R plane implies stronger metal-support interactions leading to a low sulfidation degree and shorter MoS 2 slabs. Both A and M facets, of similar crystallographic structure, display an intermediate behaviors in terms of sulfidation rate and MoS 2 size in line with intermediary metal-support interactions. Polarization-dependent Grazing-Incidence-EXAFS experiments as well as HR HAADF-STEM analysis allow us to demonstrate a surface-dependent orientation of MoS 2 slabs. A predominant basal bonding is suggested on the C (0001) plane in agreement with the existence of weak metal-support interactions. Conversely, a random orientation (edge and basal-bonding) is observed for the other planes. Generalization of these conclusions to industrial catalysts is proposed based on the comparison of the surface structure of the various model -Al 2 O 3 orientations used in this work and the predominantly exposed -Al 2 O 3 surfaces ((110), (100) and (111)).

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“…In comparison with Mo catalysts, W based ones are less documented in literature . Although a considerable amount of research has been made on their activity, selectivity and in general catalytic properties of the W catalysts, an accurate description of the active sites is still lacking . So far the available CO spectra representing W‐based catalyst are rather limited, and no reports were established on the assignment of their specific IR/CO bands, neither on the quantification of these edge sites.…”

Section: Introductionmentioning

confidence: 99%

“…[18] Although a considerable amount of research has been made on their activity, selectivity and in general catalytic properties of the W catalysts, an accurate description of the active sites is still lacking. [13,19,20] So far the available CO spectra representing W-based catalyst are rather limited, and no reports were established on the assignment of their specific IR/CO bands, neither on the quantification of these edge sites. Hence, this paper presents an insight into the sulfided W/Al 2 O 3 system characterized through IR spectroscopy and DFT calculation.…”

Section: Introductionmentioning

confidence: 99%

Structure and Quantification of Edge Sites of WS₂/Al₂O₃ Catalysts Coupling IR/CO Spectroscopy and DFT Calculations

et al. 2020

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IR spectroscopy of CO adsorption (IR/CO) and Density Functional Theory (DFT) calculations on sulfide W/Al2O3 catalyst were investigated for an insight into the sulfide edge sites. Parallel between experimental and theoretical results allow to assign the ν(CO) bands at 2121 and 2066 cm−1 to CO adsorption on M‐ and S‐edge sites of WS2 phase, respectively. Through a careful analysis of CO spectra on well‐selected W catalysts, the molar attenuation coefficients for CO adsorbed on the two exposed edges could be determined. This allowed the morphology of WS2 slabs to be calculated. This work shows that increasing the W loading (6–20 wt% W) changes the slab morphology from an almost pure triangle exhibiting mostly M‐edge to a truncated triangle. On W as well as on Mo sulfide catalysts, IR spectroscopy and DFT calculation show that CO adsorption allows to account for M‐ and S‐edge sites, and thus of the morphology of sulfide slabs. It was shown that increasing the W loading shifts the slab morphology from a triangle exposing predominantly M‐edge towards a more hexagonal shape. For close to monolayer coverage of alumina, Mo and W sulfide slabs present similar shape i. e. truncated triangle. However, edge sites of WS2 slabs clearly exhibit greater stability under H2 atmosphere than Mo sulfided ones.

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Highly Active Nonpromoted Hydrotreating Catalysts through the Controlled Growth of a Supported Hexagonal WS₂ Phase

Cited by 40 publications

References 79 publications

3D Tungsten-Doped MoS₂Nanostructure: A Low-Cost, Facile Prepared Catalyst for Hydrogen Evolution Reaction

3D Tungsten-Doped MoS₂Nanostructure: A Low-Cost, Facile Prepared Catalyst for Hydrogen Evolution Reaction

Surface-dependent sulfidation and orientation of MoS2 slabs on alumina-supported model hydrodesulfurization catalysts

Structure and Quantification of Edge Sites of WS₂/Al₂O₃ Catalysts Coupling IR/CO Spectroscopy and DFT Calculations

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Highly Active Nonpromoted Hydrotreating Catalysts through the Controlled Growth of a Supported Hexagonal WS2 Phase

Cited by 40 publications

References 79 publications

3D Tungsten-Doped MoS2Nanostructure: A Low-Cost, Facile Prepared Catalyst for Hydrogen Evolution Reaction

3D Tungsten-Doped MoS2Nanostructure: A Low-Cost, Facile Prepared Catalyst for Hydrogen Evolution Reaction

Surface-dependent sulfidation and orientation of MoS2 slabs on alumina-supported model hydrodesulfurization catalysts

Structure and Quantification of Edge Sites of WS2/Al2O3 Catalysts Coupling IR/CO Spectroscopy and DFT Calculations

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Product

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Highly Active Nonpromoted Hydrotreating Catalysts through the Controlled Growth of a Supported Hexagonal WS₂ Phase

3D Tungsten-Doped MoS₂Nanostructure: A Low-Cost, Facile Prepared Catalyst for Hydrogen Evolution Reaction

3D Tungsten-Doped MoS₂Nanostructure: A Low-Cost, Facile Prepared Catalyst for Hydrogen Evolution Reaction

Structure and Quantification of Edge Sites of WS₂/Al₂O₃ Catalysts Coupling IR/CO Spectroscopy and DFT Calculations