Atomistic simulations on the carbidisation processes in Pd nanoparticles

Kordatos, A., Mohammed, K., Vakili, R., Goguet, A., Manyar, H., Gibson, E. , Carravetta, M., Wells, P. and Skylaris, C. - K. (2023) Atomistic simulations on the carbidisation processes in Pd nanoparticles. RSC Advances, 13(9), pp. 5619-5626. (doi: 10.1039/D2RA07462A) (PMID:36798744) (PMCID:PMC9926891)

Abstract

The formation of interstitial PdCx nanoparticles (NPs) is investigated through DFT calculations. Insights on the mechanisms of carbidisation are obtained whilst the material's behaviour under conditions of increasing C-concentration is examined. Incorporation of C atoms in the Pd octahedral interstitial sites is occurring through the [111] facet with an activation energy barrier of 19.3–35.7 kJ mol−1 whilst migration through the [100] facet corresponds to higher activation energy barriers of 124.5–127.4 kJ mol−1. Furthermore, interstitial-type diffusion shows that C will preferentially migrate and reside at the octahedral interstitial sites in the subsurface region with limited mobility towards the core of the NP. For low C-concentrations, migration from the surface into the interstitial sites of the NPs is thermodynamically favored, resulting in the formation of interstitial carbide. Carbidisation reaction energies are exothermic up to 11–14% of C-concentration and slightly vary depending on the shape of the structure. The reaction mechanisms turn to endothermic for higher concentration levels showing that C will preferentially reside on the surface making the interstitial carbide formation unfavorable. As experimentally observed, our simulations confirm that there is a maximum concentration of C in Pd carbide NPs opening the way for further computational investigations on the activity of Pd carbides in directed catalysis.

• Item Type: Articles
• Additional Information: AK, KM and RV are grateful to EPSRC (grant number EP/ V000691/1) for postdoctoral funding. We are grateful to The Materials and Molecular Modelling MMM Hub (EPSRC grant number EP/T022213/1) for access to the Young supercomputer, the UKCP consortium (EPSRC grant number EP/P022030/1) for access to the ARCHER2 supercomputer and the University of Southampton for access to the Iridis5 supercomputer.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Gibson, Dr Emma
• Authors: Kordatos, A., Mohammed, K., Vakili, R., Goguet, A., Manyar, H., Gibson, E., Carravetta, M., Wells, P., and Skylaris, C. - K.
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: RSC Advances
• Publisher: Royal Society of Chemistry
• ISSN: 2046-2069
• ISSN (Online): 2046-2069
• Published Online: 14 February 2023
• Copyright Holders: Copyright © 2023 The Authors
• First Published: First published in RSC Advances 13(9): 5619-5626
• Publisher Policy: Reproduced under a Creative Commons License

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
309447		Nitridic and Carbidic Interstitial Pd Nanoparticles for Directed Catalysis	Emma Gibson	Engineering and Physical Sciences Research Council (EPSRC)	520536101 - EP/V000691/1	Chemistry