Interactions of incident H atoms with metal surfaces

Hofman, Michelle S.; Wang, Dwayne Z.; Yang, Yuxin; Koel, Bruce E.

doi:10.1016/j.surfrep.2018.06.001

Cited by 26 publications

(18 citation statements)

References 226 publications

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“…The heating rate was 3 K/s. TPD was conducted monitoring these 14 masses: 2, 3, 4, 16,17,18,19,20,28,30,32,34,40, and 44 amu. We assign 32 amu to CD 2 O and 34 amu to CD 3 OD based on matching cracking ratios in our experiments and NIST.…”

Section: Methodsmentioning

confidence: 99%

Hydrogenation of CO on Ni(110) by Energetic Deuterium

et al. 2018

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The presence of energetic hydrogen species in a plasma-enhanced catalysis reactor for CO2 or CH4 reforming could potentially lead to different hydrogenation rates and mechanisms for surface adsorbates, such as carbon monoxide (CO). Hydrogenation of CO on the Ni(110) surface at 100 K under ultrahigh vacuum (UHV) conditions has been studied using coadsorbed surface deuterium (D), subsurface D, and incident D atoms and D2 + ions. Surface-bound D adatoms did not react with coadsorbed CO to form formaldehyde (CD2O) and methanol (CD3OD) in temperature-programmed desorption (TPD) measurements. In contrast, subsurface D formed by incident D atoms can hydrogenate postadsorbed CO in subsequent TPD measurements to form CD2O and CD3OD in characteristic reaction limited thermal desorption peaks at 170 K. Subsurface D formed by 400 eV D2 + ions also produces these products but in peaks at 240 K. D atoms from the gas phase incident on a CO saturated Ni(110) surface at 100 K only formed CD2O in TPD, whereas using 100 eV D2 + ions in a similar experiment formed both CD2O and CD3OD in TPD. Incident D2 + ions were less reactive than subsurface D for the hydrogenation of CO on the Ni(110) surface. Our previous Born–Oppenheimer molecular dynamics (BOMD) simulations have shown that the direct impact of H atoms on a partially CO-covered Ni(110) surface do not hydrogenate CO via an Eley–Rideal or hot-atom mechanism and in this work the BOMD simulations show that the direct impact of H atoms on a clean Ni(110) surface do form the subsurface and bulk hydrogen, which supports the role of subsurface D in this reaction. This information will be useful for a more comprehensive understanding of the reactivity of energetic hydrogen and its role in hydrogenation for plasma-enhanced catalysis over Ni-based catalysts.

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Section: Methodsmentioning

confidence: 99%

Hydrogenation of CO on Ni(110) by Energetic Deuterium

et al. 2018

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“…In case of head-on collision of two hard spheres with masses m 1 and m 2 , the BCM predicts an accommodation coefficient for translational inelasticity, α, as shown in eq . α goes to zero as the mass of one of the particles becomes small compared to the other. Despite this, experimental observations show that H atoms adsorb easily to metals even at high incidence energies …”

Section: Inelastic Scattering Of H-atoms From Metal Surfacesmentioning

confidence: 99%

“…Despite this, experimental observations show that H atoms adsorb easily to metals even at high incidence energies. 153 …”

Section: Inelastic Scattering Of H-atoms From Metal Surfacesmentioning

confidence: 99%

Inelastic Scattering of H Atoms from Surfaces

2021

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We have developed an instrument that uses photolysis of hydrogen halides to produce nearly monoenergetic hydrogen atom beams and Rydberg atom tagging to obtain accurate angle-resolved time-of-flight distributions of atoms scattered from surfaces. The surfaces are prepared under strict ultrahigh vacuum conditions. Data from these experiments can provide excellent benchmarks for theory, from which it is possible to obtain an atomic scale understanding of the underlying dynamical processes governing H atom adsorption. In this way, the mechanism of adsorption on metals is revealed, showing a penetration–resurfacing mechanism that relies on electronic excitation of the metal by the H atom to succeed. Contrasting this, when H atoms collide at graphene surfaces, the dynamics of bond formation involving at least four carbon atoms govern adsorption. Future perspectives of H atom scattering from surfaces are also outlined.

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“…The heats Q H in Table 1 were taken from the literature experimental data and were assumed structure insensitive that is not always true [38,39]. However, this assumption seems acceptable in the present research study, because the Q H is much less important for the catalytic ammonia synthesis [40] than the bond strength [6] and activity in the hydrogenation reaction [33] of N species.…”

Section: Theoreticalmentioning

confidence: 99%

Design of Active Centers in Ammonia Synthesis on Mo-Based Catalysts: A Theoretical Study

Cholach

Bryliakova

2020

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The strong Mo-N bond restrains the catalytic activity of metallic Mo in ammonia synthesis. In this study, the semi-empirical calculations in conjunction with the density functional theory calculations, Brønsted-Evans-Polanyi relationship and microkinetic modeling were used to evaluate the rate of ammonia synthesis on model active sites of Mo-based alloys, nitrides, and clusters with a modified Mo-N bond. It was found that active sites of binary alloys Mo δ Me 1−δ (0 ≤ δ ≤ 1; Me = Co, Pt, Ir, Rh) show the synergetic behavior. The sites of ternary Mo 3 Me 3 N (Me = Mo, Co, Pt, Ir) and Mo 2 N-type nitrides revealed higher activities than sites on Mo planes due to an extra Mo bond with the lattice N atom. The sites of octahedral clusters Mo 3 Me 3 N (Me = Mo, Co, Ir, Pt) exhibited higher catalytic activity than the sites of nitrides because their Me-N bonds are weaker than Mo-N. It was also found that tetragonal Mo 2 Me 2 (Me = Co, Pt, Ir) and bi-tetragonal clusters Mo 3 Me 2 (Me = Co, Ir, Pt) are the best cases because their sites provide the optimal combination of local structure and thermodynamics. Catalytic activities of the most active sites, relative to the Fe-C 7 center, were found to change in the row 18.4 (threefold site Mo 2 Ir 1 in cluster Mo 3 Ir 2 ), 7.3 (Mo 2 in cluster Mo 2 Ir 2 ), 3.9 (Mo 2 Pt 1 in cluster Mo 3 Ir 3 N), 3.8 (M 3 on alloy Mo 0.78 Ir 0.22 ), 2.0 [Mo 3 Pt 1 on the plane (100) of Mo 3 Pt 3 N], 0.57 [Mo 3 on the plane (111) of Mo 2 N], and 0.03 [Mo 4 on the plane Mo(110)-(1 × 2)]. The design of tailor-made catalytic sites suggested in this paper can probably be applied to other catalytic systems.

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Interactions of incident H atoms with metal surfaces

Cited by 26 publications

References 226 publications

Hydrogenation of CO on Ni(110) by Energetic Deuterium

Hydrogenation of CO on Ni(110) by Energetic Deuterium

Inelastic Scattering of H Atoms from Surfaces

Design of Active Centers in Ammonia Synthesis on Mo-Based Catalysts: A Theoretical Study

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