Ten-electron count rule for the binding of adsorbates on single-atom alloy catalysts

Single-atom alloys have recently emerged as highly active and selective alloy catalysts. Unlike pure metals, single-atom alloys escape the well-established conceptual framework developed nearly three decades ago for predicting catalytic performance. Although this offers the opportunity to explore so far unattainable chemistries, this leaves us without a simple guide for the design of single-atom alloys able to catalyse targeted reactions. Here, based on thousands of density functional theory calculations, we reveal a 10-electron count rule for the binding of adsorbates on the dopant atoms, usually the active sites, of single-atom alloy surfaces. A simple molecular orbital approach rationalizes this rule and the nature of the adsorbate–dopant interaction. In addition, our intuitive model can accelerate the rational design of single-atom alloy catalysts. Indeed, we illustrate how the unique insights provided by the electron count rule help identify the most promising dopant for an industrially relevant hydrogenation reaction, thereby reducing the number of potential materials by more than one order of magnitude

Rational design of heterogeneous catalysts for biomass conversion – Inputs from computational chemistry

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Alumina in hot water: stable or not stable? That is the question!

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Understanding the stability of γ-Alumina in aqueous medium for biomass conversion

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Ten-electron count rule for the binding of adsorbates on single-atom alloy catalysts.

Acknowledgements: We thank E. C. H. Sykes for discussions and feedback and members of the ICE group for discussions. Via our membership of the UK High-End Computing Materials Chemistry Consortium, which is funded by the Engineering and Physical Sciences Research Council (EP/R029431), this work used the UK Materials and Molecular Modelling Hub for computational resources, which is partially funded by Engineering and Physical Sciences Research Council (EP/T022212 and EP/P020194). We thank University College London high-performance computing (Myriad@UCL) for the use of their facilities and support. J.S. is grateful for support from a Feodor Lynen Research Fellowship from the Alexander von Humboldt Foundation. R.R., A.M. and M.S. acknowledge financial support from the Leverhulme Trust (grant RPG-2018-209), and R.R. and M.S. gratefully acknowledge funding from the European Union’s Horizon 2020 research and innovation programme under grant 814416 (ReaxPro).Funder: European Union’s Horizon 2020 (grant No 814416)Funder: Feodor Lynen Research Fellowship from the Alexander von Humboldt FoundationSingle-atom alloys have recently emerged as highly active and selective alloy catalysts. Unlike pure metals, single-atom alloys escape the well-established conceptual framework developed nearly three decades ago for predicting catalytic performance. Although this offers the opportunity to explore so far unattainable chemistries, this leaves us without a simple guide for the design of single-atom alloys able to catalyse targeted reactions. Here, based on thousands of density functional theory calculations, we reveal a 10-electron count rule for the binding of adsorbates on the dopant atoms, usually the active sites, of single-atom alloy surfaces. A simple molecular orbital approach rationalizes this rule and the nature of the adsorbate-dopant interaction. In addition, our intuitive model can accelerate the rational design of single-atom alloy catalysts. Indeed, we illustrate how the unique insights provided by the electron count rule help identify the most promising dopant for an industrially relevant hydrogenation reaction, thereby reducing the number of potential materials by more than one order of magnitude

Reactivity of Single-Atom Alloys as Easy as Counting to Ten

Single-Atom Alloys (SAAs) have recently emerged as highly active and selective alloy catalysts. Unlike pure metals, SAAs escape the well-established conceptual framework developed nearly three decades ago for predicting catalytic performance. Here, based on high throughput density functional theory calculations, we reveal a 10-electron count rule for the binding of adsorbates on the dopant of SAA surfaces. A simple molecular orbital approach rationalises this rule and the nature of the adsorbate/dopant interaction. In addition, our intuitive model can accelerate the rational design of SAA catalysts. Indeed, we illustrate how the unique insights provided by the electron count rule help identify the most promising dopant for an industrially relevant hydrogenation reaction, thereby reducing the number of potential materials by more than one order of magnitude

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

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

Mechanistic investigations at the alumina/water interfαace

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Elucidating the Reactivity of Oxygenates on Single-Atom Alloy Catalysts.

Publication status: PublishedDoping isolated transition metal atoms into the surface of coinage-metal hosts to form single-atom alloys (SAAs) can significantly improve the catalytic activity and selectivity of their monometallic counterparts. These atomically dispersed dopant metals on the SAA surface act as highly active sites for various bond coupling and activation reactions. In this study, we investigate the catalytic properties of SAAs with different bimetallic combinations [Ni-, Pd-, Pt-, and Rh-doped Cu(111), Ag(111), and Au(111)] for chemistries involving oxygenates relevant to biomass reforming. Density functional theory is employed to calculate and compare the formation energies of species such as methoxy (CH3O), methanol (CH3OH), and hydroxymethyl (CH2OH), thereby understanding the stability of these adsorbates on SAAs. Activation energies and reaction energies of C-O coupling, C-H activation, and O-H activation on these oxygenates are then computed. Analysis of the data in terms of thermochemical linear scaling and Bro̷nsted-Evans-Polanyi relationship shows that some SAAs have the potential to combine weak binding with low activation energies, thereby exhibiting enhanced catalytic behavior over their monometallic counterparts for key elementary steps of oxygenate conversion. This work contributes to the discovery and development of SAA catalysts toward greener technologies, having potential applications in the transition from fossil to renewable fuels and chemicals

Structuration and Dynamics of Interfacial Liquid Water at Hydrated gamma-Alumina Determined by Ab Initio Molecular Simulations: Implications for Nanoparticle Stability

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