DFT Global Optimization of Gas-Phase Subnanometer Ru–Pt Clusters

Demiroğlu, İlker; Yao, Kezi; Hussein, Heider A.; Johnston, Roy L.

doi:10.1021/acs.jpcc.6b11329

Cited by 46 publications

(33 citation statements)

References 52 publications

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“…Higher binding energy indicates higher stability. As expected, due to the increase in the average number of metal-metal bonds, the binding energy generally increases with increasing cluster size, as previously reported for different metallic systems [70,71,93,94]. Pure Au clusters are relatively less stable (having lower Eb values) than pure Cu clusters of the same size.…”

Section: Energetic Analysissupporting

confidence: 86%

“…All of the ΔHL plots show marked odd-even alternations, with larger ΔHL values for even-atom (and, hence, even-electron) clusters and smaller values for odd-atom (odd-electron) clusters. This behaviour has previously been explained in terms of the electronic shell model [93][94][95][96][97][98][99]. For the free pure and mono-substituted clusters, N=6 and N=8 tend to have the highest ΔHL values, which is consistent with the ∆2E plots, since high HOMO-LUMO gaps typically correlate with low total electronic energy (stabilisation of filled orbitals).…”

Section: Energetic Analysissupporting

confidence: 79%

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Physico-Chemical Insights into Gas-Phase and Oxide-Supported Sub-Nanometre AuCu Clusters

Hussein

Gao

Hou

et al. 2019

Zeitschrift Für Physikalische Chemie

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Catalysis by AuCu nanoclusters is a promising scientific field. However, our fundamental understanding of the underlying mechanisms of mixing in AuCu clusters at the sub-nanometre scale and their physico-chemical properties in both the gas-phase and on oxide supports is limited. We have identified the global minima of gas-phase and MgO(100)-supported AuCu clusters with 3–10 atoms using the Mexican Enhanced Genetic Algorithm coupled with density functional theory. Au and Cu adatoms and supported dimers have been also simulated at the same level of theory. The most stable composition, as calculated from mixing and binding energies, is obtained when the Cu proportion is close to 50%. The structures of the most stable free AuCu clusters exhibit Cu-core/Au-shell segregation. On the MgO surface however, there is a preference for Cu atoms to lie at the cluster-substrate interface. Due to the interplay between the number of interfacial Cu atoms and surface-induced cluster rearrangement, on the MgO surface 3D structures become more stable than 2D structures. The O-site of MgO surface is found to be the most favourable adsorption site for both metals. All dimers favour vertical (V) configurations on the surface and their adsorption energies are in the order: AuCu < CuCu < AuAu < AuCu (where the underlined atom is bound to the O-site). For both adatoms and AuCu dimers, adsorption via Cu is more favourable than Au-adsorbed configurations, but, this disagrees with the ordering for the pure dimers due to a combination of electron transfer and the metal-on-top effect. Binding energy (and second difference) and HOMO-LUMO gap calculations show that even-atom (even-electron) clusters are more stable than the neighbouring odd-atom (odd- electron) clusters, which is expected for closed- and open-shell systems. Supporting AuCu clusters on the MgO(100) surface decreases the charge transfer between Au and Cu atoms calculated in free clusters. The results of this study may serve as a foundation for designing better AuCu catalysts.

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Section: Energetic Analysissupporting

confidence: 86%

Section: Energetic Analysissupporting

confidence: 79%

Physico-Chemical Insights into Gas-Phase and Oxide-Supported Sub-Nanometre AuCu Clusters

Hussein

Gao

Hou

et al. 2019

Zeitschrift Für Physikalische Chemie

Self Cite

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“…The BE for binary and ternary clusters (Song et al, 2005; Demiroglu et al, 2017) is given by Equations (3) and (4):…”

Section: Theoretical Approachmentioning

confidence: 99%

A Global Optimizer for Nanoclusters

2019

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We have developed an algorithm to automatically build the global minimum and other low-energy minima of nanoclusters. This method is implemented in PyAR (https://github.com/anooplab/pyar) program. The global optimization in PyAR involves two parts, generation of several trial geometries and gradient-based local optimization of the trial geometries. While generating the trial geometries, a Tabu list is used for storing the information of the already used trial geometries to avoid using the similar trial geometries. In this recursive algorithm, an n-sized cluster is built from the geometries of n−1 clusters. The overall procedure automatically generates many unique minimum energy geometries of clusters with size from 2 up to n using this evolutionary growth strategy. We have used our strategy on some of the well-studied clusters such as Pd, Pt, Au, and Al homometallic clusters, Ru-Pt and Au-Pt binary clusters, and Ag-Au-Pt ternary cluster. We have analyzed some of the popular parameters to characterize the clusters, such as relative energy, singlet-triplet energy difference, binding energy, second-order energy difference, and mixing energy, and compared with the reported properties.

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“…It was recently shown that alloying ruthenium-oxide with chromium could improve stability and activity of the catalyst in acidic media [51]. Computational work by Demiroglou et al predicted that alloying with platinum increases the ruthenium cluster's stability [52]. A systematic experimental investigation of the effect of doping or alloying ruthenium/ ruthenium oxide clusters is still lacking.…”

Section: Model Systems For Oer Catalysts In Acidic Mediamentioning

confidence: 99%

Few-atom cluster model systems for a hydrogen economy

Vanbuel

Ferrari

Janssens

2020

Advances in Physics: X

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To increase the share of renewable zero-emission energy sources, such as wind and solar power, in our energy supply, the problem of their intermittency needs to be addressed. One way to do so is by buffering excess renewable energy via the production of hydrogen, which can be stored for later use after re-electrification. Such a clean, renewable energy cycle based on hydrogen is commonly referred to as the hydrogen economy. This review deals with cluster model systems of the three main components of the hydrogen economy, i.e. hydrogen generation, hydrogen storage and hydrogen re-electrification, and their basic physical principles. We then present examples of contemporary research on few atom clusters, both in the gas phase and deposited, to show that by studying these clusters as simplified models a mechanistic understanding of the underlying physical and chemical processes can be obtained. Such an understanding will inspire and enable the design of novel materials needed for advancing the hydrogen economy.

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DFT Global Optimization of Gas-Phase Subnanometer Ru–Pt Clusters

Cited by 46 publications

References 52 publications

Physico-Chemical Insights into Gas-Phase and Oxide-Supported Sub-Nanometre AuCu Clusters

Physico-Chemical Insights into Gas-Phase and Oxide-Supported Sub-Nanometre AuCu Clusters

A Global Optimizer for Nanoclusters

Few-atom cluster model systems for a hydrogen economy

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