Melting Properties and Structural Evolution of (Agx-Pd1x)256 Bimetallic Nanoclusters Supported on SWCNT: A Molecular Dynamics Simulation

Yaghoubi, Hamzeh

doi:10.1016/j.molliq.2016.12.110

Cited by 5 publications

(4 citation statements)

References 50 publications

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“…A method of achieving activity–selectivity balance for hydrogenation has been to alloy highly active group 10 metals (Ni, Pd, Pt) with noble group 11 metals (Cu, Ag, Au), which demonstrate low H 2 activation because of their full d-shell or vice versa. − In these systems, group 11 metals segregate to the surface after annealing, whereas group 10 metals migrate to the subsurface, forming core@shell nanostructures . The thermodynamics of such segregation phenomenon has been studied extensively in the computational literature as a function of size mismatch, miscibility, composition, cluster size, cluster shape, and temperature, especially for Pd-doped group 11 systems: Pd@Cu; ,,− Pd@Ag; − and Pd@Au. ,,,− …”

Section: Introductionmentioning

confidence: 99%

Automated Detection and Characterization of Surface Restructuring Events in Bimetallic Catalysts

et al. 2019

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Surface restructuring in bimetallic systems has recently been shown to play a crucial role in heterogeneous catalysis. In particular, the segregation in binary alloys can be reversed in the presence of strongly bound adsorbates. Mechanistic characterization of such restructuring phenomena at the atomic level remains scarce and challenging due to the large configurational space that must be explored. To this end, we propose an 1 2 automated method to discover elementary surface restructuring processes in an unbiased fashion, using Pd/Ag as an example. We employ high-temperature classical molecular dynamics (MD) to rapidly detect restructuring events, isolate them, and optimize using density functional theory (DFT). In addition to confirming the known exchange descent mechanism, our systematic approach has revealed three new predominant classes of events at step edges of close-packed surfaces that have not been considered before: (1) vacancy insertion; (2) direct exchange; (3) interlayer exchange. The discovered events enable us to construct the complete set of mechanistic pathways by which Pd is incorporated into the Ag host in vacuum at the single-atom limit. These atomistic insights provide a step toward systematic understanding and engineering of surface segregation dynamics in bimetallic catalysts.

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Section: Introductionmentioning

confidence: 99%

Automated Detection and Characterization of Surface Restructuring Events in Bimetallic Catalysts

et al. 2019

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“…Moreover, it has been found that unsupported NPs have a tendency to agglomerate; therefore, catalytic activity is difficult . However, it has been demonstrated that the thermodynamic stability and thus catalytic activity of NPs can be enhanced through the use of various appropriate materials to encapsulate or support metal NPs. − For example, Galeano et al demonstrated that YSNPs consisting of a AuPt core and a graphitic carbon shell (AuPt@C) have high electrocatalytic stability . Liu et al demonstrated that Au@carbon YSNPs have excellent catalytic activity in the reduction reaction of o -nitrophenol .…”

Section: Introductionmentioning

confidence: 99%

“…Yaghoubi studied the heating and cooling processes of free and supported AgPd bimetallic NPs on single-walled carbon nanotubes (SWCNTs) by MD simulation. The results showed that supported AgPd NPs have higher thermal stability compared to free AgPd NPs …”

Section: Introductionmentioning

confidence: 99%

Boron Nitride- and Graphene-Supported Trimetallic Yolk–Shell and Hollow Nanoparticles

Akbarzadeh

Mehrjouei

Abbaspour

et al. 2022

Ind. Eng. Chem. Res.

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In this study, the stability of yolk–shell and hollow Ni@PdAu and PdAu@Ni nanoparticles in free state and supported on boron nitride and graphene substrates was investigated at 300 K using molecular dynamics simulations. To this end, analyses of several parameters such as relative stability, surface energy, coordination number, number of surface atoms, bond length, displacement vector, and atomic strain were employed. Results show that the yolk–shell and hollow Ni@PdAu nanoparticles are more stable than yolk–shell and hollow PdAu@Ni nanoparticles in free and supported states due to the less surface energy. Furthermore, results show that the hollow nanoparticles are more stable than yolk–shell nanoparticles in all states. In addition, results show that the void and hollow core in yolk–shell and hollow nanoparticles are unstable and collapse due to the contraction and expansion of the core and shell, which lead to the formation of the core–shell and quasi–Janus structures in hollow and yolk–shell nanoparticles, respectively. Moreover, nanoparticles create a quasi–ellipsoid structure with low density and high coordination number on the boron nitride. The yolk–shell and hollow nanoparticles are the most stable on the boron nitride due to the smaller displacement and variation of the atomic bond length and lower atomic strain, which are caused by the strong nonbonded interaction, good atomic match, and placement of the Ni, Au, and Pd atoms on the middle position of the boron nitride hexagonal structure. Generally, this study demonstrated that the stability of yolk–shell and hollow nanoparticles can be tuned by the substrate–nanoparticle interaction.

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“…The thermal and segregation properties of monometallic and bimetallic nanomaterials have been studied quite extensively using empirical force field potential methods. − In particular, the melting and segregation behavior of PtAu systems has been studied using classical force fields. , Yang et al reported on the melting behavior of core–shell icosahedral NPs containing 561 atoms. Their molecular dynamics (MD) simulations showed that Au atoms remain predominantly in the shell region even near the melting transition.…”

Section: Introductionmentioning

confidence: 99%

Thermal Properties and Segregation Behavior of Pt Nanowires Modified with Au, Ag, and Pd Atoms: A Classical Molecular Dynamics Study

et al. 2019

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Platinum nanowires (NWs) have been reported to be catalytically active toward the oxygen reduction reaction (ORR). The edge modification of Pt NWs with metals M (M = Au, Ag, or Pd) may have a positive impact on the overall ORR activity by facilitating diffusion of adsorbed oxygen, Oads, and hydroxyl groups, OHads, between the {001} and {111} terraces. In the present study, we have employed classical molecular dynamics simulations to investigate the segregation behavior of Au, Ag, and Pd decorating the edges of Pt NWs. We observe that, under vacuum conditions, Pd prefers to diffuse toward the core rather than stay on the NW surface. Ag and Au atoms are mobile at temperatures as low as 900 K; they remain on the surface but do not appear to be preferentially more stable at edge sites. To effect segregation of Au and Ag atoms toward the edge, we propose annealing in the presence of different reactive gas environments. Overall, our study suggests potential experimental steps required for the synthesis of Pt nanowires and nanoparticles with improved Oads and OHads interfacet diffusion rates and consequently an improved ORR activity.

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Melting Properties and Structural Evolution of (Agx-Pd1x)256 Bimetallic Nanoclusters Supported on SWCNT: A Molecular Dynamics Simulation

Cited by 5 publications

References 50 publications

Automated Detection and Characterization of Surface Restructuring Events in Bimetallic Catalysts

Automated Detection and Characterization of Surface Restructuring Events in Bimetallic Catalysts

Boron Nitride- and Graphene-Supported Trimetallic Yolk–Shell and Hollow Nanoparticles

Thermal Properties and Segregation Behavior of Pt Nanowires Modified with Au, Ag, and Pd Atoms: A Classical Molecular Dynamics Study

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