Atomic configurations of Pd atoms in PdAu(111) bimetallic surfaces investigated using the first-principles pseudopotential plane wave approach

Yuan, Dingwang; Gong, X. G.; Wu, Ruqian

doi:10.1103/physrevb.75.085428

Cited by 73 publications

(58 citation statements)

References 28 publications

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“…1 are presented in Table I. 26 So, in our calculations, PW91 functional is only chosen to reveal the "ensemble effect" for the CO oxidation on Pd ensembles over Au(111) surface. 44 The revised Perdew-Burke-Ernzerhof (RPBE) functional, extrapolation method, and GGA + U type functional offer some improvement.…”

Section: Resultsmentioning

confidence: 99%

“…At low CO pressures and temperature, the isolated Pd monomer is the most stable atomic ensemble on Aubased catalysts with low Pd coverage. 26 Density functional theory (DFT) calculations indicated that the dissociative energy barrier of O 2 strongly depends on the size of contiguous Pd ensembles, and the molecular adsorption state is energetically favorable on the small Pd aggregates (e.g., dimer and trimer). 12,[23][24][25] The experimental investigations suggested a superior reactivity of CO oxidation which is attributed to the role of contiguous Pd atoms on Pd-Au alloy catalyst, and the contiguous Pd sites are crucial to dissociate the O 2 .…”

Section: Introductionmentioning

confidence: 99%

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Catalytic activity of Pd ensembles over Au(111) surface for CO oxidation: A first-principles study

Yuan

Chen

2011

The Journal of Chemical Physics

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Employing the first-principles pseudopotential plane-wave methods and nudged-elastic-band simulations, we studied the reaction of CO oxidation on Pd-decorated Au(111) surface. We found that the contiguous Pd ensembles are required for the CO + O(2) reaction. Interestingly, Pd dimer is an active site for the two-step reaction of CO+O(2)→OOCO→CO(2)+O, and a low energy barrier (0.29 eV) is found for the formation of the intermediate metastable state (OOCO) compared to the barrier of 0.69 eV on Pd trimer. Furthermore, the residual atomic O in the CO + O(2) reaction can be removed by another CO on Pd dimer with the barrier of 0.56 eV close to the value of 0.52 eV on Pd monomer via Langmuir-Hinshelwood mechanism. The higher energy barriers (0.96 and 0.64 eV) are also found for the CO + O reaction on Pd trimers. The calculated results indicate Pd dimer is highly reactive for CO oxidation by O(2) via association mechanism on Pd-decorated Au(111) surface.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Catalytic activity of Pd ensembles over Au(111) surface for CO oxidation: A first-principles study

Yuan

Chen

2011

The Journal of Chemical Physics

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“…This is in agreement with the negative formation energy of the alloy in the bulk, 44 with experimental observations, 27 and with recent theoretical results. 45 For the layer-by-layer surfaces, PdAu ͑A͒ and ͑B͒, the formation of aggregates is more energy demanding for the alloys with ͑A͒ configuration than for those with ͑B͒ configuration, up to 0.41 eV. This effect can be explained by the fact that the number of heterometallic ͑Au-Pd͒ contacts in the segregated structures of ͑B͒ composition is larger than that of ͑A͒.…”

Section: A Stability Of the Bimetallic Systemsmentioning

confidence: 92%

Temperature and pressure effects in CO titration of ensembles in PdAu(111) alloys using first principles

García-Mota

López

2010

Phys. Rev. B

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In surface science, CO is a suitable probe to test the properties of metals in different chemical environments. We have analyzed CO adsorption on different PdAu alloys at both low and medium Pd content through a theoretical approach. CO is adsorbed on several sites, and the ensemble rules both the CO stretching frequency and the binding energies. Multiple CO adsorption on large ensembles ͑dimers͒ is likely at very low temperatures or high CO pressures. As a consequence, at low temperatures, the vibrational spectra of CO on the PdAu͑111͒ alloy can lead to the identification of dimers as singletons. This can lead to misinterpretations of the nature of the sites and the wrong identification of ensembles that are fundamental both in chemical and electrochemical processes. According to our first principles based thermodynamic model, CO-induced segregation is possible for PdAu͑111͒ at moderate CO pressures, about 10 −2 Torr.

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“…37 In addition, the mechanisms for preferential nucleation and the role of embedded Pd atoms in Au surface layer have been addressed theoretically by several authors. 25,[38][39][40] The reasons for such contrast differences between Pd and Au atoms were not completely explained. The interpretation of dark regions as Pd species embedded in the Au surface is further supported by an analysis of the electronic contrast by differential conductivity (dI/dV) maps as discussed in Sec.…”

Section: B Cluster Deposition At Different Energy Regimesmentioning

confidence: 99%

Energetic regimes and growth mechanisms of pulsed laser deposited Pd clusters on Au(111) investigated byin situscanning tunneling microscopy

et al. 2011

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Pulsed laser deposition (PLD) and in situ scanning tunneling microscopy (STM) have been employed here to investigate different deposition regimes for the synthesis of Pd nanoislands on Au(111). Atom-by-atom deposition at high kinetic energy or cluster deposition at different kinetic energies are allowed by PLD depending on experimental conditions. At variance with evaporation, which results in Pd island nucleation at the elbows of the 22 × √ 3 herringbone reconstruction of Au (111), PLD in vacuum leads to random island nucleation with a profound modification of surface reconstruction. In addition, deposition of preformed Pd clusters can be obtained by ablating in the presence of a background gas, and the deposits turn out to be strongly affected by both the energetic regime and by the complex anisotropic structure of the substrate surface. Low energy deposition allowed us to deposit ultrafine clusters (<2 nm), which aggregate in islands at preferential sites of the Au(111) reconstructed surface. Comparison with atom-by-atom deposition (i.e. evaporation), in which island size is strongly related with coverage and leads to lifting of the reconstruction at a coverage well below 40%, shows that low energy deposition by PLD results in a cluster arrangement nicely following the underlying surface reconstruction, in parallel rows at 40% coverage and in a zig-zag fashion for coverages up to 70%. Analysis of this deposition regime reveals that it follows a deposition diffusion aggregation (DDA) model of growth with some peculiar characteristics related to the supporting Au(111) surface reconstruction.

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Atomic configurations of Pd atoms in PdAu(111) bimetallic surfaces investigated using the first-principles pseudopotential plane wave approach

Cited by 73 publications

References 28 publications

Catalytic activity of Pd ensembles over Au(111) surface for CO oxidation: A first-principles study

Catalytic activity of Pd ensembles over Au(111) surface for CO oxidation: A first-principles study

Temperature and pressure effects in CO titration of ensembles in PdAu(111) alloys using first principles

Energetic regimes and growth mechanisms of pulsed laser deposited Pd clusters on Au(111) investigated byin situscanning tunneling microscopy

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