TOUCAN: TOwards an Understanding of CAtalysis on Nanoalloys

Lead Research Organisation: University of Cambridge
Department Name: Chemistry

Abstract

Nanoparticles differ in many ways from their "bulk" or "liquid" structures. Nanoparticles of transition metals have been widely used for accelerating important chemical reactions, thanks to their high surface to volume ratios and increasing surface energy when the cluster size decreases to a few tens of nanometers. Of particular interest are bi- and multi-metallic nanoparticles (the so-called "nanoalloys") due to the richness of structures and mixing patterns that they can exhibit and the control of chemical and physical properties that this affords.

Computational tools play a central role in designing and tailoring of nanomaterials, allowing us to find the "magic" nanoparticles for target applications, since the computing power will recreate and investigate in-silico the experimental conditions in order to suggest optimal candidates to industrial partners. A fundamental use of first-principles simulations in nanoalloy science focuses on the chemical reactions that they induce. It has been experimentally shown that heteroepitaxial grown strained over-layers can present chemical properties different than those of the unstrained surface of the same elements. This fact has been confirmed by first-principles calculations. However, at the nanoscale, due to their peculiar surface and bulk geometries, as well as various chemical orderings, even the characterization of chemisorption sites on nanoalloys is not an easy task.

In this proposed research programme, binary nanoalloys will be investigated for their potential catalytic properties. This project will focus mainly on Pt- alloys (i.e. PtAg and PtAu), Ni-alloys (i.e. AgNi, NiPt), Pd-alloys (i.e. PdAg, and PdPt), Co-alloys (i.e. AgCo and CoPt) and Fe-alloys (i.e. FePt and FeCo). Specific chemical reactions with a strong influence in the field of sustainable energy will be considered, such as CO2-capture, biomass processes - e.g. involving dissociation of CO and CH4, and NH3 dissociation for hydrogen production.

Two conditions must be fulfilled for a spontaneous chemical transformation to occur in the laboratory: (1) the final state must have a lower free energy than the initial state, and (2) there must be at least one pathway that allows the transformation to take place within a reasonable time. In simple chemical reactions, the transformation pathway (the reaction coordinate) is often well understood, which makes it possible to compute reaction rates and predict how external influences (such as catalysts) will affect these rates. However, there are many transformations, including
structural relaxation and nucleation in solids, where the trajectory can follow complex paths that correspond to cooperative or sequential motion of many degrees of freedom. From the point of view of computer simulation, such pathways correspond to rare events, because the waiting time required for the process of interest to occur is very large compared to the time taken for the event itself. To understand and control such complex transformations at the microscopic level, we need to characterise the underlying, high-dimensional potential energy landscape and sample the rare events directly. Based on this knowledge, we aim to predict the relevant transformation pathways and rates and, more ambitiously, to understand how we can influence these rates.

The project is comprised of four inter-linked projects which are aligned with the aims and objectives set out above:

P1. Construction of the Nanoalloy Database

P2. Determination of Thermal Stabilities of Nanoalloy Isomers

P3. Chemisorption Maps

P4. Reaction Rates for Molecular Dissociation on Nanoalloys

Publications

10 25 50

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Baldock R (2016) Determining pressure-temperature phase diagrams of materials in Physical Review B

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Baldock RJN (2017) Constant-pressure nested sampling with atomistic dynamics. in Physical review. E

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Calvo F (2013) Communication: Kinetics of chemical ordering in Ag-Au and Ag-Ni nanoalloys. in The Journal of chemical physics

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Calvo F (2016) Grand and Semigrand Canonical Basin-Hopping. in Journal of chemical theory and computation

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De S (2016) Comparing molecules and solids across structural and alchemical space. in Physical chemistry chemical physics : PCCP

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Eckhoff M (2017) Structure and Thermodynamics of Metal Clusters on Atomically Smooth Substrates. in The journal of physical chemistry letters

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John ST (2017) Many-Body Coarse-Grained Interactions Using Gaussian Approximation Potentials. in The journal of physical chemistry. B

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Packwood D (2016) A universal preconditioner for simulating condensed phase materials. in The Journal of chemical physics

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Pártay LB (2017) Polytypism in the ground state structure of the Lennard-Jonesium. in Physical chemistry chemical physics : PCCP

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Pártay LB (2014) Nested sampling for materials: the case of hard spheres. in Physical review. E, Statistical, nonlinear, and soft matter physics

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Rossi K (2018) Thermodynamics of CuPt nanoalloys. in Scientific reports

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Schebarchov D (2013) Communication: a new paradigm for structure prediction in multicomponent systems. in The Journal of chemical physics

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Schebarchov D (2014) Structure prediction for multicomponent materials using biminima. in Physical review letters

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Schebarchov D (2015) Quasi-combinatorial energy landscapes for nanoalloy structure optimisation. in Physical chemistry chemical physics : PCCP

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Schebarchov D (2014) Degenerate Ising model for atomistic simulation of crystal-melt interfaces. in The Journal of chemical physics

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Stecher T (2014) Free Energy Surface Reconstruction from Umbrella Samples Using Gaussian Process Regression. in Journal of chemical theory and computation

 
Description We have discovered new ways to employ computer simulations to predict the structure and thermodynamics of nanoalloys.
Exploitation Route Dissemination of the public domain computer programs.
Sectors Chemicals,Digital/Communication/Information Technologies (including Software)

 
Description Mostly through dissemination of public domain computer programs. For nanoalloy structure prediction, it is the GMIN, PATHSAMPLE and OPTIM programs that are relevant.
First Year Of Impact 2013
Sector Chemicals
Impact Types Societal

 
Description ERC Advanced Grant
Amount £2,000,000 (GBP)
Funding ID ERC-AdG 267369 
Organisation European Commission 
Sector Public
Country European Union (EU)
Start 03/2011 
End 03/2016
 
Description Knowledge Transfer Fellowship
Amount £60,000 (GBP)
Organisation University of Sheffield 
Department EPSRC KTA Knowledge Transfer Account
Sector Academic/University
Country United Kingdom
Start 11/2015 
End 10/2016
 
Description Programme grant for self-organisation involving Cambridge, Oxford and Birmingham.
Amount £3,187,961 (GBP)
Funding ID EP/I001352/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 01/2010 
End 01/2015
 
Title GMIN 
Description computer program for global optimisation and enhanced thermodynamic sampling. 
Type Of Material Improvements to research infrastructure 
Provided To Others? Yes  
Impact worldwide use of group software. This is a key research tool, under constant development, including new approaches for multifunnel landscapes. 
URL http://www-wales.ch.cam.ac.uk/GMIN/
 
Title OPTIM 
Description Program for characterising pathways and mechanisms 
Type Of Material Improvements to research infrastructure 
Provided To Others? Yes  
Impact wordwide use of group software, This is a key research tool, under constant development. 
URL http://www-wales.ch.cam.ac.uk/OPTIM/
 
Title pele 
Description Graphical suite of python routines for exploring energy landscapes 
Type Of Material Improvements to research infrastructure 
Year Produced 2013 
Provided To Others? Yes  
Impact Widespread use of group theory and simulation tools 
URL http://pele-python.github.io/pele/
 
Title Cambridge Landscapes Database 
Description Software downloads, documentation, and global minima/structure predictions for atomic and molecular clusters and soft and condensed matter 
Type Of Material Computer model/algorithm 
Year Produced 2006 
Provided To Others? Yes  
Impact Widespread use of structure predictions by both theory and experimental teams 
URL http://www-wales.ch.cam.ac.uk/CCD.html
 
Title GMIN 
Description global optimisation 
Type Of Technology Software 
Year Produced 2016 
Open Source License? Yes  
Impact widespread use of basin-hopping 
URL http://www-wales.ch.cam.ac.uk/GMIN/
 
Title PATHSAMPLE 
Description Harvesting a kinetic transition network for analysis of rare event dynamics. Calculation of phenomenological rates. 
Type Of Technology Software 
Year Produced 2016 
Open Source License? Yes  
Impact Widespread use of discrete path sampling 
URL http://www-wales.ch.cam.ac.uk/PATHSAMPLE/
 
Title pele 
Description Graphical based suit of software based on python for exploring energy landscapes 
Type Of Technology Software 
Year Produced 2016 
Open Source License? Yes  
Impact Easy introduction to the potential energy landscape approach for new users. 
URL http://pele-python.github.io/pele/
 
Description 4th TYC Energy Material Workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The workshop was focused on shaping nanocatalysts. Both experimental and theoretical researchers participated, sparking valuable cross-talk between the two groups.
Year(s) Of Engagement Activity 2016
URL http://www.thomasyoungcentre.org/events/energy-materials-workshop/workshop-programme/
 
Description Departmental Seminar (Auckland, New Zealand) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Around 20 students and academics (from the Physics Department at Auckland University) attended the talk showcasing the nanoalloy-related work in the Wales group. The talk was followed by a Q&A session that sparked interesting discussions.
Year(s) Of Engagement Activity 2015
 
Description Departmental Seminar (Wellington, New Zealand) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Around 10 students and academics (from the School of Chemical and Physical Sciences at the Victoria University of Wellington) attended the talk showcasing the nanoalloy-related work in the Wales group. The talk was followed by a Q&A session that sparked interesting discussions.
Year(s) Of Engagement Activity 2015
 
Description Energy landscapes workshop and conference (Durham) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Participants in your research and patient groups
Results and Impact Around 50 researchers attended a talk on optimisation methodology , which sparked questions and discussion afterwards.

A number of attendees have expressed interest in using the described methodology in various contexts.
Year(s) Of Engagement Activity 2014
URL https://www.dur.ac.uk/soft.matter/events/energylandscapes/programme/
 
Description Energy landscapes: From molecules to nanodevices Bochum 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Participants in your research and patient groups
Results and Impact Seminar at the ICAMS centre, Bochum, 9 January 2012.

New collaborations
Year(s) Of Engagement Activity 2012
 
Description Inaugural ESF Energy Landscapes Meeting 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Participants in your research or patient groups
Results and Impact The ESF funded an inaugural Energy Landscapes meeting,in Obergurgl Austria, 2012, which featured several talks on

amyloid, including one from the PDRA on the original BBSRC grant. Prof. Wales was Conference Chair and Organiser. 40,000 euros

Prof. Wales was Conference Chair and Organiser.

no actual impacts realised to date
Year(s) Of Engagement Activity 2012
 
Description Q and A session 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Hockerill Anglo-European College.

Successful university applications
Year(s) Of Engagement Activity 2011
 
Description Research Visit (Birmingham, UK) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Study participants or study members
Results and Impact A group of 15-20 students and academics attended my talk at Birmingham University. The purpose was to present the nanoalloy structure prediction methods developed in the Wales group and discuss the possibility of applying them to DFT-based (as opposed to completely empirical) models.
Year(s) Of Engagement Activity 2015
 
Description Research Visit (Knoxville, Tennessee) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact A talk in the Mathematics Department at the University of Tennessee, Knoxville, attended by a group of 10-15 students and academics. The purpose was to showcase the computational methods developed in the Wales group, and establish a collaboration to develop efficient methods for simulating the kinetics of nanoalloy formation.
Year(s) Of Engagement Activity 2015
URL http://www.math.utk.edu/colloquium/past/11_16_15.html