Mapping surface segregation of single-atom Pt dispersed in M surfaces (M = Cu, Ag, Au, Ni, Pd, Co, Rh and Ir) under hydrogen pressure at various temperatures

Wang, Qing; Zhu, Bi; Tielens, Frederik; Tichit, Didier; Guesmi, Hazar

doi:10.1016/j.apsusc.2021.149217

Cited by 15 publications

(14 citation statements)

References 48 publications

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“…The SOE of H(ads) is however more favorable on the PdCu SAA than on the PdAu SAA, resulting in the former being better than the latter as a hydrogenation catalyst . Spectator species with large SOEs have also been shown to modulate the performance of SAA catalysts, with CO(ads) or I(ads) being prominent examples of these effects, , or even to stabilize SAA surfaces by anchoring dopants at the surface of the catalyst. ,− Therefore, the ability to understand factors affecting the SOEs and predict SOEs for a wide range of chemical intermediates on various SAA surfaces is key to the development of this new class of catalysts.…”

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confidence: 99%

Stick or Spill? Scaling Relationships for the Binding Energies of Adsorbates on Single-Atom Alloy Catalysts

Réocreux

Sykes

Michaelides

et al. 2022

J. Phys. Chem. Lett.

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Single-atom alloy catalysts combine catalytically active metal atoms, present as dopants, with the selectivity of coinage metal hosts. Determining whether adsorbates stick at the dopant or spill over onto the host is key to understanding catalytic mechanisms on these materials. Despite a growing body of work, simple descriptors for the prediction of spillover energies (SOEs), i.e., the relative stability of an adsorbate on the dopant versus the host site, are not yet available. Using Density Functional Theory (DFT) calculations on a large set of adsorbates, we identify the dopant charge and the SOE of carbon as suitable descriptors. Combining them into a linear surrogate model, we can reproduce DFT-computed SOEs within 0.06 eV mean absolute error. More importantly, our work provides an intuitive theoretical framework, based on the concepts of electrostatic interactions and covalency, that explains SOE trends and can guide the rational design of future single-atom alloy catalysts.

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mentioning

confidence: 99%

Stick or Spill? Scaling Relationships for the Binding Energies of Adsorbates on Single-Atom Alloy Catalysts

Réocreux

Sykes

Michaelides

et al. 2022

J. Phys. Chem. Lett.

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“…Experimental and theoretical studies agree that for Ir–Au nanoparticle segregation is energetically favored over mixing. ,,, It was also found that these bimetallic nanoparticles exhibit a surface structure that is much closer to (100) than to (111) surfaces . In order to emulate the structure of these nanoparticles, we focus our study on Ir, Au, and Ir–Au (100) surfaces.…”

Section: Theoretical Methodsmentioning

confidence: 99%

Bimetallic Synergy on Iridium–Gold Catalysts for the CO Oxidation Reaction

2022

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IrAu bimetallic structures are presented as ideal catalysts in the CO oxidation reaction (COOR). In this work, density functional theory (DFT) is employed to explore O2 dissociation and CO2 formation on IrAu bimetallic (BM) surface models. We found that a new reactive path would take place at the BM interface, outperforming the catalytic properties of pure surfaces. Overall, we show here the first attempt to address a correlation between the BM interface and catalytic improvement in the highly active BM system. Our results have major implications for the design of efficient catalysts with a superior synergistic catalytic design in terms of the system composition.

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“…It is important to keep in mind that, especially at high temperatures, NPs are dynamic materials: dopants can migrate within the surface and between the surface and the bulk. During the preparation of the catalyst or under the operating conditions, adsorbates can strongly affect the stability of SAAs . Accounting for the adsorbate spillover energy is therefore crucial to constructing a good model of the surface state of the NP under the experimental conditions. ,, The study of such effects is ongoing, but some interesting results have already been demonstrated.…”

Section: Adsorption On Single-atom Alloysmentioning

confidence: 99%

One Decade of Computational Studies on Single-Atom Alloys: Is In Silico Design within Reach?

Réocreux

Stamatakis

2021

Acc. Chem. Res.

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Metrics & MoreArticle Recommendations CONSPECTUS: Single-Atom alloys (SAAs) are an emerging class of materials consisting of a coinage metal (Cu, Ag, and Au) doped, at the single-atom limit, with another metal. As catalysts, coinage metals are rarely very active on their own, but when they are, they exhibit high selectivity. On the other hand, transition metals are usually very active but not as selective. Incorporating transition metals (guest elements) into coinage metals (host material) is therefore appealing for combining the activity and selectivity of each constituent in a balanced way. Additionally, first-principles calculations have shown that single atoms embedded in the surface of a coinage metal can exhibit emergent properties. Here, we describe how computational studies based on density functional theory (DFT) and kinetic Monte Carlo (KMC) simulations, often undertaken in close collaboration with experimental research groups, have shaped, over the past decade, the way we understand SAA catalysis. This Account reviews our contributions in elucidating the stability of SAAs, their electronic structure, and the way adsorbates interact and react on SAA catalytic surfaces. By studying in detail the processes that affect the stability of the SAA phase, we have shown that out of several bimetallic combinations of coinage metals with prominent Pt-group metals only PtCu and PdCu are stable surface alloys under vacuum. However, more surface alloy structures are possible in the presence of adsorbates because the latter can stabilize, via strong binding, dopants in the surface of the material. More interestingly, a large number of these surface alloys are resistant to the aggregation of dopant atoms into clusters, thereby favoring the SAA structure. These major results from DFT calculations serve as a guide for experimentalists to explore new SAA catalysts. Further analysis has shown that SAAs have a unique electronic structure with a very sharp d-band feature close to the Fermi level, analogous to the electronic structure of molecular entities. This is one of the reasons that SAAs are particularly sought after: although they are metallic nanoparticles, they have properties akin to those of homogeneous catalysts. In this context, we have contributed extensive screening studies, focusing on molecular fragments of catalytic relevance on a range of SAAs, which have driven the identification of new catalysts. We have also explored the rich chemistry of two-adsorbate systems via kinetic modeling, demonstrating how a spectator species with greater affinity for the dopant can modulate the reactivity of the catalyst via the so-called (punctured) molecular cork effect. Since the first experimental characterization of SAAs about a decade ago, theoretical models have been able to support and explain various experimental observations. These models have served as benchmarks for assessing the predictive capability of the underlying theoretical methods. In turn, the predictions that have been delivered have guided and continue t...

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Mapping surface segregation of single-atom Pt dispersed in M surfaces (M = Cu, Ag, Au, Ni, Pd, Co, Rh and Ir) under hydrogen pressure at various temperatures

Cited by 15 publications

References 48 publications

Stick or Spill? Scaling Relationships for the Binding Energies of Adsorbates on Single-Atom Alloy Catalysts

Stick or Spill? Scaling Relationships for the Binding Energies of Adsorbates on Single-Atom Alloy Catalysts

Bimetallic Synergy on Iridium–Gold Catalysts for the CO Oxidation Reaction

One Decade of Computational Studies on Single-Atom Alloys: Is In Silico Design within Reach?

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