Structure and stability of clean and adsorbate covered intermetallic PdGa surfaces: A first principles study

Kumar, Nandha; Ghosh, Prasenjit

doi:10.1016/j.susc.2015.09.005

Cited by 7 publications

(9 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is only 0.21 eV lower than that observed by Prinz et al on the (1̅1̅1̅)Pd 3 surface . We also note that, over a wide range of Ga chemical potential (even under Ga rich condition), the (100)PG l surface is theoretically predicted to be one of the most probable exposed facets in the PdGa crystallites grown. − Hence, this surface termination may be also responsible for the high selectivity exhibited by PdGa nanocrystallites …”

Section: Results and Discussionmentioning

confidence: 45%

“…For the case of dissociated hydrogen (coadsorption of two atomic H) the lowest energy configuration is the one in which the hydrogen atoms are on the Pd–Pd bridge site. Of the two Pd atoms that form the bridge site, one of the Pd atoms is in the topmost layer, while the second one is in the second (PG l , PG h ) or third layer (PGp) . The binding of atomic hydrogens is exothermic on PGp and PG h surfaces with −0.60 and −0.28 eV binding energies.…”

Section: Results and Discussionmentioning

confidence: 99%

“…To avoid the interactions between the periodic images of the slabs we have used a vacuum of 12 Å. Other details of the computational parameters and the surface models are described in our previous report …”

Section: Methods and Computational Detailsmentioning

confidence: 99%

“…Of the two Pd atoms that form the bridge site, one of the Pd atoms is in the topmost layer, while the second one is in the second (PG l , PG h ) or third layer (PGp). 23 The binding of atomic hydrogens is exothermic on PGp and PG h surfaces with −0.60 and −0.28 eV binding energies. In contrast, on PG l coadsorption of atomic H is endothermic with a binding energy of about 0.23 eV.…”

Section: H 2 and H + H Adsorptionmentioning

confidence: 99%

“…For the (110) surface we have considered the termination where there is a Pd and a Ga atom in the top layer and a Pd atom in the second layer (PGp surface). We chose these specific terminations because these are the most stable ones predicted by our calculations . Further, we have elucidated the role of surface roughness and ensemble effects in determining the reactivity and selectivity of these model catalysts.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Selectivity and Reactivity of Pd-Rich PdGa Surfaces toward Selective Hydrogenation of Acetylene: Interplay of Surface Roughness and Ensemble Effect

Kumar

Ghosh

2016

J. Phys. Chem. C

Self Cite

View full text Add to dashboard Cite

Recent experiments have shown that PdGa nanocrystallites act as highly selective and reactive catalyst for selective hydrogenation of acetylene to ethylene. Motivated by these experimental results we have studied the mechanism and energetics of the above reaction on low indexed (100) and (110) PdGa surfaces using first-principles density functional theory based calculations. We find that the energetically favorable (100) surface created by cleaving the crystal in the less dense region shows reasonably good selectivity and high reactivity. The reactivity on this surface is comparable to that observed on Pd(111) surfaces. Since this surface termination is stable over a wide range of Ga chemical potential and hence is likely to occupy a substantial fraction of the surface area of PdGa nanocrystallites, we suggest this termination is responsible for the selectivity and reactivity exhibited by PdGa. In contrast to other surfaces where hydrogen adsorption and dissociation is followed by acetylene adsorption and hydrogenation, on this surface we identify a novel reaction mechanism in which hydrogen dissociation occurs in the presence of acetylene. A careful analysis of the factors determining the selectivity shows that selectivity results due to an interplay between surface roughness and chemical nature of the reactive ensemble.

show abstract

Section: Results and Discussionmentioning

confidence: 45%

Section: Results and Discussionmentioning

confidence: 99%

Section: Methods and Computational Detailsmentioning

confidence: 99%

Section: H 2 and H + H Adsorptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations