Study of defects in Pd thin films on Au(100) using molecular dynamics

Pereira, Zenner S.; Silva, E. Z. da

doi:10.1103/physrevb.81.195417

Cited by 9 publications

(14 citation statements)

References 34 publications

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“…Details of the model building, the potentials, and the simulation methods are described in the Methods section. The observation of epitaxial growth in the model is consistent with experimental data for flat surfaces, which suggest epitaxial growth for at least the first 6 to 13 atomic layers in the outer shell, and with previous molecular dynamics simulations that suggest epitaxial growth for 8 or more atomic layers in the outer shell . As a difference to extended surfaces, three-dimensional nanoparticles have also been suggested to sustain significantly more strain, shifting the critical layer of the transition from epitaxial growth to the bulk lattice spacing further away from the metal–metal interface, which concurs with our observations of 20 epitaxial atomic layers.…”

Section: Resultssupporting

confidence: 91%

“…The boundaries of the two metals have been probed on extended (100) − and (111) , surfaces as well as on multisurface nanocrystals of few nanometer size, ,, primarily through use of transmission electron microscopy (TEM). Conversely, the 3D internal atomic structure of core–shell nanoparticles larger than a few nanometers remains an open question.…”

mentioning

confidence: 99%

“…The development of a bulk Pd lattice atop a Au(111) surface has been reported as close as eight atomic layers from the interface, and a gradual lattice transition of Pd atop a Au(100) surface has been reported between 6 and 30 atomic layers . Observations of alloying to relieve stress along the boundary are also known; however, annealing of the particle well above room temperature was necessary. , Molecular dynamics (MD) studies using embedded atom method (EAM) potentials have suggested that Pd deposited on Au(100) surfaces produces stacking faults along (111) planes after 9 atomic layers of deposition, allowing the Pd to relax to its normal lattice …”

mentioning

confidence: 99%

“… , We explain the characteristic deformation patterns at the Au–Pd interface in the context of the strain field and available experimental data, ,− as well as insights from previous simulations. Prior simulations have been limited to flat surfaces of about 100 000 atoms or nanoparticles of less than 5000 atoms , and oftentimes used more approximate potentials.…”

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confidence: 99%

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Atomic-Scale Structure and Stress Release Mechanism in Core–Shell Nanoparticles

et al. 2018

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Core−shell nanoparticles find applications in catalysts, sensors, and theranostics. The full internal 3D atomic structure, however, cannot be resolved by current imaging and diffraction techniques. We analyzed the atomic positions and stress-release mechanism in a cubic Au−Pd core−shell nanoparticle in approximately 1000 times higher resolution than current experimental techniques using large-scale molecular dynamics simulation to overcome these limitations. The core− shell nanocube of 73 nm size was modeled similarly to solution synthesis by random epitaxial deposition of a 4 nm thick shell of Pd atoms onto a Au core of 65 nm side length using reliable interatomic potentials. The internal structure reveals specific deformations and stress relaxation mechanisms that are caused by the +4.8% lattice mismatch of gold relative to palladium and differential confinement of extended particle facets, edges, and corners by one, two, or three Au−Pd interfaces, respectively. The three-dimensional lattice strain causes long-range, arc-like bending of atomic rows along the faces and edges of the particle, especially near the Au−Pd interface, a bulging deformation of the Pd shell, and stacking faults in the Pd shell at the corners of the particle. The strain pattern and mechanism of stress release were further characterized by profiles of the atomic layer spacing in the principal crystallographic directions. Accordingly, strain in the Pd shell is several times larger in the extended facets than near the edges and corners of the nanoparticle, which likely affects adsorption, optical, and electrochemical properties. The findings are consistent with available experimental data, including 3D reconstructions of the same cubic nanoparticle by coherent diffractive imaging (CDI) and may be verified by more powerful experimental techniques in the future. The stress release mechanisms are representative for cubic core−shell nanoparticles with fcc structure and can be explored for different shapes by the same methods.

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Section: Resultssupporting

confidence: 91%

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confidence: 99%

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Atomic-Scale Structure and Stress Release Mechanism in Core–Shell Nanoparticles

et al. 2018

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“…Pd-Au bimetallic systems have been widely studied for applications in a vast number of catalytic reactions, such as CO oxidation, [1][2][3][4][5][6] butadiene selective hydrogenation, 7 H 2 O 2 production, [8][9][10][11] cyclotrimerization of acetylene, 12 vinyl acetate (VA) synthesis, [13][14][15] and alcohol oxidation. 16 Several forms of Pd-Au bimetallic catalysts have been identified and reported, including nanoclusters, [17][18][19][20] Pd clusters on Au nanoparticles, 21 Pd overlayers on Au surface, 22,23 and random alloy surfaces with varying Pd ensembles. 24,25 Among the different forms of Pd-Au bimetallic catalysts, the Pd/Au surface alloy derived by dispersing Pd on Au substrates received particular attention, partly because it is a potential substitute for the expensive Pt cathode catalyst in the oxygen reduction reaction (ORR).…”

Section: Introductionmentioning

confidence: 99%

First principles study of oxygen adsorption and dissociation on the Pd/Au surface alloys

Wang

Yang

et al. 2011

Phys. Chem. Chem. Phys.

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The formation of Pd/Au surfaces and their catalytic performance toward oxygen dissociation were investigated using periodic density functional methods. We show that Pd can readily incorporate into the second layer of Au(100) and Au(111) substrates with the assistance of Au vacancies. Pd/Au(100) exhibits better catalytic activity toward oxygen dissociation than Pd/Au(111). Specifically, the sub-layer Pd atoms of Pd/Au(100) can promote the oxygen dissociation and stabilize the surface structure after adsorbing oxygen atoms. On the contrary, the sub-layer Pd atoms of Pd/Au(111) slightly hinder the oxygen dissociation.

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