First-principles insights into ammonia decomposition on WC (0001) surface terminated by W and C

Rao, Xianfa; Lou, Yitao; Zhou, Yang; Zhang, Jianbo; Zhong, Shenweng

doi:10.1016/j.apsusc.2021.150635

Cited by 14 publications

(9 citation statements)

References 29 publications

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“…WC with C-termination more favors hydrogen production via NH 3 decomposition, while WC with W-termination is easily poisoned via N atoms, resulting in the difficult N atoms combinative desorption. 13 WC with C-termination performs higher activity toward with that with W-termination. 14 WC with W-termination easily activate CO into C and O atoms, 15 and then the successive hydrogenation of C atom to generate CH x (x = 1−3).…”

Section: Introductionmentioning

confidence: 90%

“…For example, the termination of WC also impacts the stability of Rh 19 /WC, Rh 31 /WC and Rh 37 /WC catalyst, in which Rh 19 supported on WC with W-termination is the most stable compared with that on C-termination, while the Rh 31 and Rh 37 supported on C-termination is the most stable instead of W-termination. WC with C-termination more favors hydrogen production via NH 3 decomposition, while WC with W-termination is easily poisoned via N atoms, resulting in the difficult N atoms combinative desorption . WC with C-termination performs higher activity toward H 2 O dehydrogenation to OH compared with that with W-termination .…”

Section: Introductionmentioning

confidence: 99%

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Syngas Conversion to C₂ Species over WC and M/WC (M = Cu or Rh) Catalysts: Identifying the Function of Surface Termination and Supported Metal Type

Zhao

Guan

et al. 2022

ACS Appl. Mater. Interfaces

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Improving the selectivity and activity of C 2 species from syngas is still a challenge. In this work, catalysts with monolayer Cu or Rh supported over WC with different surface terminations (M/WC (M = Cu or Rh)) are rationally designed to facilitate C 2 species generation. The complete reaction network is analyzed by DFT calculations. Microkinetics modeling is utilized to consider the experimental reaction temperature, pressure, and the coverage of the species. The thermal stabilities of the M/WC (M = Cu or Rh) catalysts are confirmed by AIMD simulations. The results show that the surface termination and supported metal types in the M/WC (M = Cu or Rh) catalysts can alter the existence form of abundant CH x (x = 1−3) monomer, as well as the activity and selectivity of CH x monomer and C 2 species. Among these, only the Cu/WC−C catalyst is screened out to achieve outstanding activity and selectivity for C 2 H 2 generation, attributing to that the synergistic effect of the subsurface C atoms and the surface monolayer Cu atoms presents the noble-metal-like character to promote the generation of CH x and C 2 species. This work demonstrates a new possibility for rational construction of other catalysts with the non-noble metal supported by the metal carbide, adjusting the surface termination of metal carbide and the supported metal types can present the noble-metal-like character to tune catalytic performance of C 2 species from syngas.

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Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Syngas Conversion to C₂ Species over WC and M/WC (M = Cu or Rh) Catalysts: Identifying the Function of Surface Termination and Supported Metal Type

Zhao

Guan

et al. 2022

ACS Appl. Mater. Interfaces

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“…Thus, in this work we analyze the capability of WCÀ C and WCÀ W terminations to dissociate H 2 and form a wide range of hydrogen coverages, addressing the thermodynamics conditions to achieve different Θ H values. It is worth highlighting that among WCÀ C and WCÀ W, X. Rao et al [20] and D. Siegel et al [21] found theoretically that WCÀ W was most stable than WCÀ C. These findings could address the choice of WCÀ W as the only termination to study surface chemical reactions. However, from the point of view of a practical catalyst, both WCÀ C and WCÀ W could be exposed; then, we analyze both surfaces in this work.…”

Section: Introductionmentioning

confidence: 91%

“…Thus, in this work we analyze the capability of WC−C and WC−W terminations to dissociate H 2 and form a wide range of hydrogen coverages, addressing the thermodynamics conditions to achieve different Θ H values. It is worth highlighting that among WC−C and WC−W, X. Rao et al [20] . and D. Siegel et al [21] .…”

Section: Introductionmentioning

confidence: 99%

The α‐WC(0001) Surface as a Hydrogen Sponge: A First Principle Study of H₂Dissociation and Formation of Low and High Coverages

2023

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Tungsten carbide (WC) displays a Pt-like behavior in catalysis, applied in hydrogenation processes. Numerous theoretical studies have modeled the behavior and use of adsorbed hydrogen without obtaining a general picture, missing basic links between H 2 dissociation and generation of high surface coverage (Θ H > 0.5 ML). Here, the capability of C-and Wterminations of the α-WC(0001) surface is analyzed to dissociate several H 2 molecules to produce coverages, Θ H , ranging from low to very high values (0.13 < Θ H < 2.00 ML). Density functional theory and an ab initio atomistic thermodynamic were used to achieve the conditions for H 2 dissociation. The WCÀ C surface has higher capacity to dissociate H 2 molecules than WCÀ W. However, both surfaces can reach full surface coverage, Θ H = 1 ML, at mild ambient conditions, T = 300 K and P = 1 atm, and even up to 500 K at low and high pressures. The H-adatoms on WCÀ W are more labile than on WCÀ C. The binding of adsorbates is hindered at high Θ H , implying a need to modulate Θ H according to the application. The results give the basis to understand the capabilities of WC-based catalysts in hydrogenation-related reactions, with the advantage of WC being a hydrogen reservoir at mild practical catalytic conditions.

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“…The coefficient of linear expansion of W 2 C is relatively flat and the value is not large. For WC/Ni composites, the generation of interfacial phase W 2 C helps to regulate the difference of thermophysical properties between Ni and reinforcing particles WC, thus effectively mitigating the stress concentration at the junction of Ni and reinforcing particles, which leads to particle detachment [23,24]. It is apparent that W 2 C is dispersed in the matrix as an intermediate phase.…”

Section: Thermodynamic Analysis Of Interfacial Reactionsmentioning

confidence: 99%

Preparation of high wear resistance nickel based WC coating by carefully adjusting interface structure

Fan

Ou²,

Rong³

et al. 2022

Mater. Res. Express

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In recent years, many scholars have paid attention to wear-resistant coatings for shield machine cutterheads due to their very high consumption rates. Among these coatings, nickel-based tungsten carbide (Ni-based WC) is one of the best, showing both corrosion resistance and wear resistance. However, to further improve the wear resistance of such coatings, there are still numerous issues that need to be resolved. Herein, a new method, distinct from conventional methods, is presented. Specifically, the brittle phase W2C is not widely regarded as the main wear-resistant phase, but we were surprised to find that careful adjustment of its rigid structure can yield satisfactory results. Experimental results and first-principles simulations have indicated that the friction coefficient and weight loss of a coating with a suitable distribution of W2C are only half of those of a traditional Ni-based WC coating (about five times higher than those of the substrate), which can mainly be attributed to the excellent thermal expansion coefficient and hardness of the W2C phase. As we expected, the surface morphology of the material after wear revealed that the suitable W2C layer has a well-defined friction morphology. We hope to provide new ideas for the study of Ni-based WC coatings in shield machine cutterheads.

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First-principles insights into ammonia decomposition on WC (0001) surface terminated by W and C

Cited by 14 publications

References 29 publications

Syngas Conversion to C₂ Species over WC and M/WC (M = Cu or Rh) Catalysts: Identifying the Function of Surface Termination and Supported Metal Type

Syngas Conversion to C₂ Species over WC and M/WC (M = Cu or Rh) Catalysts: Identifying the Function of Surface Termination and Supported Metal Type

The α‐WC(0001) Surface as a Hydrogen Sponge: A First Principle Study of H₂Dissociation and Formation of Low and High Coverages

Preparation of high wear resistance nickel based WC coating by carefully adjusting interface structure

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First-principles insights into ammonia decomposition on WC (0001) surface terminated by W and C

Cited by 14 publications

References 29 publications

Syngas Conversion to C2 Species over WC and M/WC (M = Cu or Rh) Catalysts: Identifying the Function of Surface Termination and Supported Metal Type

Syngas Conversion to C2 Species over WC and M/WC (M = Cu or Rh) Catalysts: Identifying the Function of Surface Termination and Supported Metal Type

The α‐WC(0001) Surface as a Hydrogen Sponge: A First Principle Study of H2Dissociation and Formation of Low and High Coverages

Preparation of high wear resistance nickel based WC coating by carefully adjusting interface structure

Contact Info

Product

Resources

About

Syngas Conversion to C₂ Species over WC and M/WC (M = Cu or Rh) Catalysts: Identifying the Function of Surface Termination and Supported Metal Type

Syngas Conversion to C₂ Species over WC and M/WC (M = Cu or Rh) Catalysts: Identifying the Function of Surface Termination and Supported Metal Type

The α‐WC(0001) Surface as a Hydrogen Sponge: A First Principle Study of H₂Dissociation and Formation of Low and High Coverages