DFT study of the M segregation on MAu alloys (M=Ni, Pd, Pt) in presence of adsorbed oxygen O and O2

Dhouib, Adnene; Guesmi, Hazar

doi:10.1016/j.cplett.2011.11.050

Cited by 50 publications

(51 citation statements)

References 41 publications

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“…We can also notice that the segregation energy of a monolayer of Pd from the second to the first layer of the slab, i.e., the energy difference between the system with the Pd-substituted first layer and system with the Pd-substituted second layer is 0.36 eV/atom. This value is similar to the calculated segregation energy of one Pd impurity in the gold matrix [12]. The computed segregation energy of Rh is 0.45 eV/atom, which is in line with the expected trend from the cohesion energies [34].…”

Section: Pd and Rh Induced Structural Electronic And Energetic Propsupporting

confidence: 75%

Interaction of Hydrogen with Au Modified by Pd and Rh in View of Electrochemical Applications

et al. 2016

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Hydrogen interaction with bimetallic Au(Pd) and Au(Rh) systems are studied with the density functional theory (DFT)-based periodic approach. Several bimetallic configurations with varying concentrations of Pd and Rh atoms in the under layer of a gold surface(111) were considered. The reactivity of the doped Au(111) toward hydrogen adsorption and absorption was related to the property modifications induced by the presence of metal dopants. DFT-computed quantities, such as the energy stability, the inter-atomic and inter-slab binding energies between gold and dopants, and the charge density were used to infer the similarities and differences between both Pd and Rh dopants in these model alloys. The hydrogen penetration into the surface is favored in the bimetallic slab configurations. The underlayer dopants affect the reactivity of the surface gold toward hydrogen adsorption in the systems with a dopant underlayer, covered by absorbed hydrogen up to a monolayer. This indicates a possibility to tune the gold surface properties of bimetallic electrodes by modulating the degree of hydrogen coverage of the inner dopant layer(s).

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Section: Pd and Rh Induced Structural Electronic And Energetic Propsupporting

confidence: 75%

Interaction of Hydrogen with Au Modified by Pd and Rh in View of Electrochemical Applications

et al. 2016

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“…This has previously been noted experimentally for dilute Pd/Cu SAA nanoparticles whereby exposure to CO pulls Pd to the surface and consequently enhances the activity of these nanoparticles towards acetylene hydrogenation [26]. Moreover, several theoretical studies have demonstrated the phenomenon of adsorbate induced segregation [27][28][29][30][31][32][33]. For example a study by Sansa et al on the CO induced segregation of single transition metal dopant atoms in Au reveals that the adsorption energy of CO is sufficient to promote dopant atom segregation to both the Au(111) and Au(100) surfaces from the bulk [32].…”

Section: Co Induced Surface Segregationmentioning

confidence: 96%

“…Additionally, we recognize that the presence of adsorbates may induce structural changes in binary alloy materials, such as segregation of atoms from the bulk into the surface layer, as well as promoting aggregation and island formation [26][27][28][29][30][31][32][33][34]. Such changes are caused by differences in adsorption behaviour between an adsorbate on each metallic component of the alloy; these differences can offset or increase the energy change upon restructuring of the material.…”

Section: Introductionmentioning

confidence: 99%

Carbon Monoxide Poisoning Resistance and Structural Stability of Single Atom Alloys

et al. 2018

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Platinum group metals (PGMs) serve as highly active catalysts in a variety of heterogeneous chemical processes. Unfortunately, their high activity is accompanied by a high affinity for CO and thus, PGMs are susceptible to poisoning. Alloying PGMs with metals exhibiting lower affinity to CO could be an effective strategy toward preventing such poisoning. In this work, we use density functional theory to demonstrate this strategy, focusing on highly dilute alloys of PGMs (Pd, Pt, Rh, Ir and Ni) with poison resistant coinage metal hosts (Cu, Ag, Au), such that individual PGM atoms are dispersed at the atomic limit forming single atom alloys (SAAs). We show that compared to the pure metals, CO exhibits lower binding strength on the majority of SAAs studied, and we use kinetic Monte Carlo simulation to obtain relevant temperature programed desorption spectra, which are found to be in good agreement with experiments. Additionally, we consider the effects of CO adsorption on the structure of SAAs. We calculate segregation energies which are indicative of the stability of dopant atoms in the bulk compared to the surface layer, as well as aggregation energies to determine the stability of isolated surface dopant atoms compared to dimer and trimer configurations. Our calculations reveal that CO adsorption induces dopant atom segregation into the surface layer for all SAAs considered here, whereas aggregation and island formation may be promoted or inhibited depending on alloy constitution and CO coverage. This observation suggests the possibility of controlling ensemble effects in novel catalyst architectures through CO-induced aggregation and kinetic trapping.

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“…The small difference in electronegativity values of Pd(2.2) and Au(2.4) can lead to weak (Pd to Au) s electron transfer [34,38] (favouring mixing in larger clusters), but favouring surface Au in smaller clusters, as the more electronegative Au atom can better stabilise the negative charge that tends to build up on the cluster surface [71]. However, it should be noted that for larger clusters reverse (Au to Pd) d -band electron donation can also occur [72,73].…”

Section: Stabilitymentioning

confidence: 99%

Application of a parallel genetic algorithm to the global optimization of medium-sized Au–Pd sub-nanometre clusters

2018

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Abstract. To contribute to the discussion of the high activity and reactivity of Au-Pd system, we have adopted the BPGA-DFT approach to study the structural and energetic properties of medium-sized AuPd sub-nanometre clusters with 11-18 atoms. We have examined the structural behaviour and stability as a function of cluster size and composition. The study suggests 2D-3D crossover points for pure Au clusters at 14 and 16 atoms, whereas pure Pd clusters are all found to be 3D. For Au-Pd nanoalloys, the role of cluster size and the influence of doping were found to be extensive and non-monotonic in altering cluster structures. Various stability criteria (e.g. binding energies, second differences in energy, and mixing energies) are used to evaluate the energetics, structures, and tendency of segregation in sub-nanometre Au-Pd clusters. HOMO-LUMO gaps were calculated to give additional information on cluster stability and a systematic homotop search was used to evaluate the energies of the generated global minima of monosubstituted clusters and the preferred doping sites, as well as confirming the validity of the BPGA-DFT approach.

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DFT study of the M segregation on MAu alloys (M=Ni, Pd, Pt) in presence of adsorbed oxygen O and O2

Cited by 50 publications

References 41 publications

Interaction of Hydrogen with Au Modified by Pd and Rh in View of Electrochemical Applications

Interaction of Hydrogen with Au Modified by Pd and Rh in View of Electrochemical Applications

Carbon Monoxide Poisoning Resistance and Structural Stability of Single Atom Alloys

Application of a parallel genetic algorithm to the global optimization of medium-sized Au–Pd sub-nanometre clusters

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