Hydrogen embedded in Ni: Production by incident atomic hydrogen and detection by high-resolution electron energy loss

Johnson, Andrew; Maynard, Kevin J.; Daley, S. P.; Yang, Qingyun; Ceyer, S. T.

doi:10.1103/physrevlett.67.927

Cited by 159 publications

(133 citation statements)

References 23 publications

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“…We posit that tunneling electrons propagating from the tip into the crystal (or vice versa at negative sample bias) scatter inelastically from hydrogen atoms in the bulk. This hypothesis is supported by the work of Ceyer and coworkers (31), in which high-resolution electron energy loss spectroscopy was used to detect the vibrational modes of H atoms embedded in a Ni crystal. From their spectra, they concluded that vibrational modes of H atoms in the bulk were unambiguously distinguishable from surface-bound H, and that these modes were excited by impact scattering of the electrons.…”

Section: Resultssupporting

confidence: 53%

Observation and manipulation of subsurface hydride in Pd{111} and its effect on surface chemical, physical, and electronic properties

Sykes

Fernandez-Torres

Nanayakkara

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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We report the observation and manipulation of hydrogen atoms beneath the surface of a Pd{111} crystal by using low-temperature scanning tunneling microscopy. These subsurface hydride sites have been postulated to have critical roles in hydrogen storage, metal embrittlement, fuel cells, and catalytic reactions, but they have been neither observed directly nor selectively populated previously. We demonstrate that the subsurface region of Pd can be populated with hydrogen atoms from the bulk by applying voltage pulses from a scanning tunneling microscope tip. This phenomenon is explained with an inelastic excitation mechanism, whereby hydrogen atoms in the bulk are excited by tunneling electrons and are promoted to more stable sites in the subsurface region. We show that this selectively placed subsurface hydride affects the electronic, geometric, and chemical properties of the surface. Specifically, we observed the effects of hydride formation on surface deformation and charge and on adsorbed hydrogen on the surface. Hydrogen segregation and overlayer vacancy ordering on the Pd{111} have been characterized and explained in terms of the surface changes attributable to selective hydrogen occupation of subsurface hydride sites in Pd{111}.atomic manipulation ͉ catalysis ͉ palladium ͉ hydrogen ͉ scanning tunneling microscopy

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Section: Resultssupporting

confidence: 53%

Observation and manipulation of subsurface hydride in Pd{111} and its effect on surface chemical, physical, and electronic properties

Sykes

Fernandez-Torres

Nanayakkara

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

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“…While for a long time carbon was considered a site blocker, Geoff Webb [78] suggested that it is the hydrogen directly connected with the carbon is the relevant species involved in hydrogenation. The traditional opinion that only surface hydrogen species participate in the hydrogenation process was also questioned by Ceyer and co-workers studying ethylene hydrogenation on Ni(111) [79]. More recently, other experimental and theoretical evidences for the important role of subsurface hydrogen were reported and it has been suggested that the carbonaceous species control the hydrogen distribution on and in the particle [80][81][82].…”

Section: Example #3: Olefin Hydrogenation: Nanoparticles Versus Singlmentioning

confidence: 94%

Models in Catalysis

2014

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The paper discusses the hierarchy of model studies with increasing complexity towards an understanding of industrial catalysts under reaction conditions. We use three case studies to document the progress in systems complexity as well as the development of instruments that allow us to approach the study of acting catalysts: magnesium oxide clusters in the gas phase, gold nanoparticles on metal oxide surfaces, and palladium nanoparticles compared to crystal surfaces. While the examples are from the field of heterogeneous catalysis, we discuss the relation to homogeneous and enzymatic catalysis.

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“…This metastable subsurface H can be prepared at low temperatures by exposure of the surface to atomic hydrogen followed by collision-induced recombinative desorption to remove the surface bound H under UHV conditions. [32][33][34] To explore the role of subsurface H (H b ) in CO 2 hydrogenation on Ni(111), we first studied CO 2 hydrogenation with surface H in the presence of subsurface H as a spectator. We then studied CO 2 hydrogenation with subsurface H as a reactant at a low coverage (2/9 ML) and a full ML coverage.…”

Section: Methodsmentioning

confidence: 99%

CO₂ Hydrogenation to Formic Acid on Ni(111)

et al. 2012

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Periodic, self-consistent, density functional theory (DFT) calculations are employed to study CO 2 hydrogenation on Ni(111). CO 2 hydrogenation with H adsorbed on the surface and with H absorbed in the subsurface is investigated systematically and the respective microscopic reaction mechanisms are elucidated. We show that on Ni(111), CO 2 hydrogenation to formate intermediate is more favorable than to carboxyl intermediate. The hydrogenation to formate goes through the unidentate structure that rapidly transforms into the bidentate structure. Further hydrogenation from formate to formic acid is energetically more difficult than formate formation. Formation of adsorbed formic acid from adsorbed CO 2 and surface hydrogen is an endothermic reaction. Because subsurface H in Ni(111) is substantially less stable compared to surface H, its reaction with adsorbed CO 2 to adsorbed formic acid is an exothermic one. Our results may have significant implications for the synthesis of liquid fuels from CO 2 and for catalytic hydrogenation reactions in general.2

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Hydrogen embedded in Ni: Production by incident atomic hydrogen and detection by high-resolution electron energy loss

Cited by 159 publications

References 23 publications

Observation and manipulation of subsurface hydride in Pd{111} and its effect on surface chemical, physical, and electronic properties

Observation and manipulation of subsurface hydride in Pd{111} and its effect on surface chemical, physical, and electronic properties

Models in Catalysis

CO₂ Hydrogenation to Formic Acid on Ni(111)

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Hydrogen embedded in Ni: Production by incident atomic hydrogen and detection by high-resolution electron energy loss

Cited by 159 publications

References 23 publications

Observation and manipulation of subsurface hydride in Pd{111} and its effect on surface chemical, physical, and electronic properties

Observation and manipulation of subsurface hydride in Pd{111} and its effect on surface chemical, physical, and electronic properties

Models in Catalysis

CO2 Hydrogenation to Formic Acid on Ni(111)

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CO₂ Hydrogenation to Formic Acid on Ni(111)