On the Mechanisms of Hydrogen Spillover in MoO<sub>3</sub>

Chen, Liang; Cooper, Alan C.; Pez, Guido P.; Cheng, Hansong

doi:10.1021/jp7119137

Cited by 111 publications

(129 citation statements)

References 34 publications

(44 reference statements)

Supporting

Mentioning

116

Contrasting

Unclassified

Order By: Relevance

“…Adsorbed water plays an important role in such migration, which was demonstrated by the calculations adequately describing the hydrogen migration over the WO 3 surface [10]: The О-Н bond dissociation energy is compensated by the simultaneous formation of a new О-Н bond. Similar mechanism was suggested for the hydrogen spillover over the MoO 3 surface [11]. The hydrogen spillover on materials incapable of reversible redox reactions is attributed to the presence of defects or impurity atoms on the support surface [12].…”

supporting

confidence: 56%

Efficiency of isotope exchange between sodium 4-phenylbenzoate and activated tritium

et al. 2015

View full text Add to dashboard Cite

The efficiency of the protium-tritium isotope exchange in the sodium 4-phenylbenzoate (PBNa) molecule on activating the reaction on a tungsten filament at 1940 K (target temperature 77 and 295 K) and on heating the substrate supported on 5% Pd/C in the presence of gaseous tritium is compared. It is shown that the reaction mechanism is laregly determined by the properties of the material on which this reaction occurs and not only by the method of generation of activated tritium species. In the reaction of tritium atom with PBNa deposited on glass walls of the reaction vessel, the isotope substitution of tritium for protium occurred by the radical mechanism, leading to the formation of [ 3 H]PBNa and hydrogenation products. It is assumed that the spillover of tritium atom over the support (carbon) surface is accompanied by polarization of the electronic shell and formation of the cluster ( 3 H + )(ē), which leads to changes in the composition of the reaction products. The combined treatment of PBNa on 5% Pd/C allows estimation of the concentration of clusters on the carbon surface, which reaches 10.9 particles per 100 nm 2 (9.2 nm 2 per cluster).Hydrogen spillover on various materials is being actively studied today, because this phenomenon underlies many catalytic reactions and can favor the development of efficient methods for hydrogen storage [1][2][3][4][5][6][7]. Interaction of hydrogen molecules with platinum group metals leads to the formation of activated hydrogen species capable of migration from the catalyst on the support. The spillover mechanism and the reactivity of the migrating species are determined by the nature of the surface over which the hydrogen activated on the catalyst migrates. Although ample experimental data [1-6] demonstrate the possibility of hydrogen spillover on various supports, the calculations made in [7] show that hydrogen spillover is efficient only on the surface of materials on which redox reactions can occur, e.g., on the surface of transition metal oxides. In this case, a proton interacting with oxygen anions migrates over the surface, which is accompanied by the electron transfer from the reduced M (n-1)+ cation to the adjacent M n+ cation [8,9]. The spillover intensity is determined by the activation energy of the proton and electron migration in the matrix. Adsorbed water plays an important role in such migration, which was demonstrated by the calculations adequately describing the hydrogen migration over the WO 3 surface [10]: The О-Н bond dissociation energy is compensated by the simultaneous formation of a new О-Н bond. Similar mechanism was suggested for the hydrogen spillover over the MoO 3 surface [11]. The hydrogen spillover on materials incapable of reversible redox reactions is attributed to the presence of defects or impurity atoms on the support surface [12].In adsorption of hydrogen atoms on materials characterized by the charge distribution on the surface or by high dipole moments, the electronic shell of the atom undergoes deformation polarization up to the f...

show abstract

supporting

confidence: 56%

Efficiency of isotope exchange between sodium 4-phenylbenzoate and activated tritium

et al. 2015

View full text Add to dashboard Cite

show abstract

“…This wealth of computational studies is contrasted by a small amount of theoretical publications in which the presence of a support was taken into account [24][25][26][27][28]. The Pt-H bond strength was calculated by Oudenhuijzen et al [24] for a Pt 4 cluster on Na 2 O and F 2 O. Bartczak et al [25] determined the adsorption path of hydrogen on Pd/MgO.…”

mentioning

confidence: 99%

“…The Pt-H bond strength was calculated by Oudenhuijzen et al [24] for a Pt 4 cluster on Na 2 O and F 2 O. Bartczak et al [25] determined the adsorption path of hydrogen on Pd/MgO. Chen et al studied the adsorption and diffusion of hydrogen for a Pt 6 cluster saturated by H atoms and supported on carbon [26] and MoO 3 [27] surfaces. The interaction between H 2 and Pt/c-Al 2 O 3 was examined by Ahmed et al [28].…”

mentioning

confidence: 99%

Computational study of the adsorption of molecular hydrogen on PdAg, PdAu, PtAg, and PtAu dimers

Matczak

2010

Reac Kinet Mech Cat

View full text Add to dashboard Cite

The adsorption and dissociation of the H 2 molecule on the PdAg, PdAu, PtAg, and PtAu heteronuclear dimers, both isolated and deposited on carbon, were investigated by means of density functional theory. It was found that the Pd and Pt ends of the isolated dimers adsorb H 2 more exoenergetically than the Ag and Au ends. The dimers were also deposited on a carbon support and it turned out that they prefer to adsorb on the support by their Pd and Pt ends rather than by the Ag and Au ends. The adsorption of H 2 on the carbon-supported dimers is somewhat less exoenergetic than that on the isolated dimers but, after the dissociation of H 2 , the binding of the H atoms to the dimers remains stronger in the presence of the support.

show abstract

“…However, recent progress in atomic hydrogen storage in nanoscale carbon materials through the so-called spillover technique [3][4][5][6][7][8][9][10][11][12][13] suggests that the chemisorbed H atoms in carbon migrate relatively easily, with kinetics much faster than that have been theoretically expected. [14][15][16] Fast kinetics is understandable for traditional H spillover 17 in metals or oxides, in which the hydrogen species involved are active protons or anions; however, atomic H migration in carbon materials runs obviously against the current understanding of C-H chemistry. Therefore, a mechanistic study of such process is necessary both on the fundamental science level and from the perspective of practical applications.…”

mentioning

confidence: 99%

Migration mechanism for atomic hydrogen in porous carbon materials

Narayanan

Zhao

Ciobanu

2012

Applied Physics Letters

View full text Add to dashboard Cite

To explain the fast kinetics of H in porous carbon, we propose that the migration relies on H hopping from a carbon nanotube (CNT) to another. Using density functional theory, we have found that the barrier for H hopping becomes smaller than that for diffusion along a tube for certain CNT separations, decreasing to less than 0.5 eV for separations of ∼3.1 Å. Such significant reduction occurs irrespective of radius, chirality, registry, and orientation of the two CNTs: the diffusion is thus facilitated by the porous nature of the material itself. The mechanism proposed is applicable for any porous carbon-based nanomaterials.

show abstract

On the Mechanisms of Hydrogen Spillover in MoO₃

Cited by 111 publications

References 34 publications

Efficiency of isotope exchange between sodium 4-phenylbenzoate and activated tritium

Efficiency of isotope exchange between sodium 4-phenylbenzoate and activated tritium

Computational study of the adsorption of molecular hydrogen on PdAg, PdAu, PtAg, and PtAu dimers

Migration mechanism for atomic hydrogen in porous carbon materials

Contact Info

Product

Resources

About

On the Mechanisms of Hydrogen Spillover in MoO3

Cited by 111 publications

References 34 publications

Efficiency of isotope exchange between sodium 4-phenylbenzoate and activated tritium

Efficiency of isotope exchange between sodium 4-phenylbenzoate and activated tritium

Computational study of the adsorption of molecular hydrogen on PdAg, PdAu, PtAg, and PtAu dimers

Migration mechanism for atomic hydrogen in porous carbon materials

Contact Info

Product

Resources

About

On the Mechanisms of Hydrogen Spillover in MoO₃