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Atomistic simulations on the carbidisation processes in Pd nanoparticles

Atomistic simulations on the carbidisation processes in Pd nanoparticles
Atomistic simulations on the carbidisation processes in Pd nanoparticles

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.

2046-2069
5619-5626
Kordatos, Apostolos
f95fcb92-92b1-4ec8-991a-de7609845493
Mohammed, Khaled
1c3c5641-4d0a-4c4d-bb26-fe733b8dbf63
Vakili, Reza
7e37d2f5-ccc7-4530-9b77-898141c35ab2
Goguet, Alexandre
4de6e217-9733-4d26-b041-ab996672d919
Manyar, Haresh
aad00507-84ce-431c-ac0b-85dc1992ad6b
Gibson, Emma
04b28c20-8197-45b9-af08-cba0d8fd710c
Carravetta, Marina
1b12fa96-4a6a-4689-ab3b-ccc68f1d7691
Wells, Peter
bc4fdc2d-a490-41bf-86cc-400edecf2266
Skylaris, Chris Kriton
8f593d13-3ace-4558-ba08-04e48211af61
Kordatos, Apostolos
f95fcb92-92b1-4ec8-991a-de7609845493
Mohammed, Khaled
1c3c5641-4d0a-4c4d-bb26-fe733b8dbf63
Vakili, Reza
7e37d2f5-ccc7-4530-9b77-898141c35ab2
Goguet, Alexandre
4de6e217-9733-4d26-b041-ab996672d919
Manyar, Haresh
aad00507-84ce-431c-ac0b-85dc1992ad6b
Gibson, Emma
04b28c20-8197-45b9-af08-cba0d8fd710c
Carravetta, Marina
1b12fa96-4a6a-4689-ab3b-ccc68f1d7691
Wells, Peter
bc4fdc2d-a490-41bf-86cc-400edecf2266
Skylaris, Chris Kriton
8f593d13-3ace-4558-ba08-04e48211af61

Kordatos, Apostolos, Mohammed, Khaled, Vakili, Reza, Goguet, Alexandre, Manyar, Haresh, Gibson, Emma, Carravetta, Marina, Wells, Peter and Skylaris, Chris Kriton (2023) Atomistic simulations on the carbidisation processes in Pd nanoparticles. RSC Advances, 13 (9), 5619-5626. (doi:10.1039/d2ra07462a).

Record type: Article

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.

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Accepted/In Press date: 8 February 2023
Published date: 14 February 2023
Additional Information: This journal is © The Royal Society of Chemistry.

Identifiers

Local EPrints ID: 476161
URI: http://eprints.soton.ac.uk/id/eprint/476161
ISSN: 2046-2069
PURE UUID: f6682af8-e924-4664-b0c1-85c360acc34d
ORCID for Apostolos Kordatos: ORCID iD orcid.org/0000-0002-0183-8142
ORCID for Khaled Mohammed: ORCID iD orcid.org/0000-0002-9538-0936
ORCID for Marina Carravetta: ORCID iD orcid.org/0000-0002-6296-2104
ORCID for Peter Wells: ORCID iD orcid.org/0000-0002-0859-9172
ORCID for Chris Kriton Skylaris: ORCID iD orcid.org/0000-0003-0258-3433

Catalogue record

Date deposited: 12 Apr 2023 16:57
Last modified: 06 Jun 2024 02:10

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Contributors

Author: Apostolos Kordatos ORCID iD
Author: Khaled Mohammed ORCID iD
Author: Reza Vakili
Author: Alexandre Goguet
Author: Haresh Manyar
Author: Emma Gibson
Author: Peter Wells ORCID iD

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