Ensemble and ligand effects on the acetylene adsorption on ordered PdxAg1−x/Pd(100) surface alloys investigated by periodic DFT study

Li, Qiang; Song, Lijuan; Pan, Lihong; Zhuang, Xinling; Ling, Mingli; Duan, Linhai

doi:10.1039/c3cp52504j

Cited by 19 publications

(17 citation statements)

References 60 publications

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“…While Ga atom becomes less positive changing from 0.893e -to 0.656e -. The negative value of work function change, indicates that, in the presence of the acetylene molecules, the electrons are easily extracted from the surface, which also indicates that the adsorption is dominated by donation rather than backdonation effects 48 Figure 1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 We also computed the stretching vibration frequencies for the adsorbed C 2 H 2 .…”

Section: Resultsmentioning

confidence: 95%

The Electronic Structure and Bonding of Acetylene on PdGa(110)

et al. 2015

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We have studied the adsorption of acetylene on the PdGa(110) surface by Density Functional Theory (DFT) calculation. Our results predict the Hollow site is the most stable location for the adsorbate. In this site, both Pd and Ga atoms interact with acetylene. This molecule is bonded with the C-C bond almost parallel to the surface. A small tilt angle of 4.1° is computed. The C atoms present a rehybridization from sp sp 2 . This rehybridization is also present in Bridge site but it is not present in the Top configuration, where the C-C-H bond angle is about 160°. We computed the total Density of State (DOS) for the system and also the projection on Pd, Ga, C and H atoms. These plots show a shift to lower energies on C and H projected states, which is an indication of stabilization after adsorption. At the same time, a reduction in the density for Pd atom directly bonded to C atom. The Crystal Orbital Overlap Population (COOP) curves show an increase in the C-C overlap population (OP) after adsorption; while, the C 2 H 2 rehybridizes to a near sp 2 geometry. The acetylene withdraws charge from the surface indicating a donation-adsorption mechanism. The formation of Pd-C and Ga-C bonds and a decrease in OP for Pd-Pd and Pd-Ga bonds are detected. We also found, in the Hollow site, a reduction in the C-C bond stretching vibrational frequency. This is an indication of the significant distortion in the adsorbed molecule. We have also found that the C-C bond breaking is unfavorable and that the semihydrogenation is 2.27 eV more stable than C 2 H 2 +H 2 in the gas phase.

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Section: Resultsmentioning

confidence: 95%

The Electronic Structure and Bonding of Acetylene on PdGa(110)

et al. 2015

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“…These findings clearly demonstrate that the most desirable structure of a highly dilute alloy surface depends on the application we are interested in. It is established that the adsorption behavior on alloy catalysts is rationalized through the so-called ensemble and ligand effects. − These effects are related to the composition and electronic structure of the active site, respectively, and determine, to a large extent, the nature of the active site. It then follows that if one could possibly find a way to engineer the architecture of the surface of highly dilute alloys, one would be able to optimize their catalytic performance according to the needs of any particular application.…”

Section: Introductionmentioning

confidence: 99%

CO-Induced Aggregation and Segregation of Highly Dilute Alloys: A Density Functional Theory Study

2019

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Highly dilute binary alloys composed of an active platinum group metal (PGM) and a more inert coinage metal are important in the field of catalysis, as they function as active and selective catalysts. Their catalytic properties depend on the surface "ensemble" of PGM atoms, whose size may be altered under reactive conditions. We use density functional theory and investigate the interaction of CO, a molecule common in numerous industrially important chemistries, with alloys that are composed of a PGM (Pt, Pd, Rh, Ir, Ni) doped in coinage metal hosts (Cu, Au, Ag). We study the adsorption of CO on the (211) step and (100) facet and compare our results to those previously obtained on the (111) facet. We determine strong correlations between the adsorption energies of CO across the facets and highlight the corresponding thermochemical scaling relations. Finally, we study the stability of isolated surface dopant atoms with respect to aggregation into clusters and segregation into the bulk, both in the presence and absence of CO. We find that strong COdopant interactions significantly influence the morphology of the catalyst surface, suggesting that it may be possible to establish control over the ensemble size of the dopant by tuning PCO.

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“…Then the generated H a spills from Pd sites to adjacent Ag metal sites. [ 65,85‐87 ] It has been revealed that the Ag sites do not adsorb alkynes and alkenes and the binding energy of spilled H a on them is less than that of Pd sites. [ 66,88‐89 ] The spilled H a species on Ag sites tend to flow back to the Pd sites and facilitate the hydrogenation of alkynes or alkenes absorbed on Pd sites.…”

Section: Resultsmentioning

confidence: 99%

Seed‐mediated Growth of AlloyedAg‐PdShells toward Alkyne Semi‐hydrogenation Reactions under Mild Conditions^†

2021

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Main observation and conclusion Ag@Ag‐Pdx core‐shell nanocomposites with various Ag/Pd ratio were deposited on Ag nanoplates using a seed growth method. When physically loaded on C3N4, Ag@Ag‐Pd0.077/C3N4 with optimized Ag/Pd ratio could accomplish high catalytic performance for the semi‐hydrogenation of phenylacetylene as well as other aliphatic (both terminal and internal alkynes) alkynes and phenylcycloalkynes containing functional groups (such as ester, hydroxyl, ethyl groups) under room temperature and 1 atm H2. The alloying and ensemble effects are used to interpret such catalytic performance.

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Ensemble and ligand effects on the acetylene adsorption on ordered PdxAg1−x/Pd(100) surface alloys investigated by periodic DFT study

Cited by 19 publications

References 60 publications

The Electronic Structure and Bonding of Acetylene on PdGa(110)

The Electronic Structure and Bonding of Acetylene on PdGa(110)

CO-Induced Aggregation and Segregation of Highly Dilute Alloys: A Density Functional Theory Study

Seed‐mediated Growth of AlloyedAg‐PdShells toward Alkyne Semi‐hydrogenation Reactions under Mild Conditions^†

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Ensemble and ligand effects on the acetylene adsorption on ordered PdxAg1−x/Pd(100) surface alloys investigated by periodic DFT study

Cited by 19 publications

References 60 publications

The Electronic Structure and Bonding of Acetylene on PdGa(110)

The Electronic Structure and Bonding of Acetylene on PdGa(110)

CO-Induced Aggregation and Segregation of Highly Dilute Alloys: A Density Functional Theory Study

Seed‐mediated Growth of AlloyedAg‐PdShells toward Alkyne Semi‐hydrogenation Reactions under Mild Conditions†

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Seed‐mediated Growth of AlloyedAg‐PdShells toward Alkyne Semi‐hydrogenation Reactions under Mild Conditions^†