Our last BIOVIA Conference had many great talks. One of the talks, @MS from Johnson Matthey gave a talk on "Modelling metallic nanoparticles: Towards more representative models".  

Watch this 20 minute video.  

Abstract:

Computational Chemistry techniques, in particular DFT, have been used widely and successfully used to study catalysis on metallic surfaces. However, with conventional DFT approaches, the computational cost scales with the number of atoms cubed. As a result, periodic supercell approaches where only one type of crystal plane is modeled, or ultrasmall so-called “magic number” regular polyhedral are widely used. Unfortunately, these model structures exhibit only a small fraction of the diverse range of surface morphologies available for molecular interaction. The development of a new generation of linear-scaling methods (such as the ONETEP program [1] via which DFT calculations on larger systems can be performed [2] has brought catalytically relevant sizes of nanoparticles (2−10 nm) into reach.

In this talk recent work on modelling metallic nanoparticles will be described, focusing on the Oxygen Reduction Reaction (ORR) in fuel cells, starting with ideal cuboctahedra nanoparticles to determine particle size effects on properties such as adsorption energies. Experimental nanoparticles are likely to deviate from these “ideal” shapes, and this introduces the risk of discrepancies arising between predictions made from DFT calculations and experimental results. Recent work on combining electron microscopy and DFT calculations [3][4] have been used to assess the differences between experimental observations and cuboctahedral/truncated-octahedral particles using a range of widely used descriptors, such as electron-density, d-band centers, and generalized coordination numbers. We use this new approach to determine the optimum particle size for which both detrimental surface roughness and particle shape effects are minimized. Following on from this work on including the effect of the support on the morphology and catalytic properties of small nanoparticles will be presented.

References
[1] Skylaris, C.-K.; et al J. Chem. Phys. 2005, 122 (8), 084119. 
[2] Wilkinson, K. A.; et al J. Chem. Theory Comput. 2014, 10 (11), 4782−4794.
[3] J. Aarons et al., Nano Lett., 17, 4003-4012, (2017)
[4] T. Ellaby et al., J. Phys. Condens. Matter, 30, 155301, (2018)
[5] L.G. Verga et al, PCCP, 2016, 18, 32713

Catalysis, CASTEP, ONETEP, metallic nanoparticles Materials Studio 

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