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DFT calculation of oxygen adsorption on platinum nanoparticles: coverage and size effects

DFT calculation of oxygen adsorption on platinum nanoparticles: coverage and size effects
DFT calculation of oxygen adsorption on platinum nanoparticles: coverage and size effects
Catalysts made of Pt nanoparticles and Pt alloys are considered state-of-the-art catalysts for the anodic and cathodic reactions involved in hydrogen fuel cells. The optimal size of such nanoparticles for each chemical reaction is an unsolved problem, which depends on environmental variables, such as reactant concentration, solvent, temperature, etc. From a theoretical point of view, this problem has been tackled mainly by observing how single key adsorbates react with different nanoparticles in controlled conditions. In this work, we use large-scale DFT calculations to examine the interplay between the Pt nanoparticle size and O coverage effects. We examine single O adsorptions for three adsorption sites on cuboctahedral platinum nanoparticles with different sizes. As we grow the nanoparticle size, the binding strength decreases and we observed a quick convergence of the adsorption energies with increasing nanoparticle size, which correlates with the calculated d-band centre for (111) Pt facets on such nanoparticles. We also carried out a detailed study of the effect of oxygen coverage with varying fractions of O monolayer coverage, computing adsorption energies per O atom for Pt 55 , Pt 147, and Pt309 nanoparticles with several O coverages. In general, the increase of O coverage led to weaker adsorption energies per O atom, and when analysing the results in terms of oxygen monolayers, this effect is more pronounced for larger nanoparticles. The O coverage dependency of the adsorption energy per O atom is analysed in terms of the O distribution for each nanoparticle size and electronic changes that the adsorbed oxygen causes to the Pt nanoparticle. In studying nanoparticle size and oxygen coverage effects simultaneously, we offer insights with DFT accuracy to help on heterogeneous catalyst design
0301-7249
1-15
Verga, Lucas Garcia
681e0d2b-083d-4478-85f6-d2eca7673c24
Aarons, Jolyon
93e68133-73b0-43e0-8c91-464920f4a503
Sarwar, M
75fc6212-1ca1-4733-bab0-0fae948ecc4d
Thompsett, D.
6f7014d2-14b6-401e-9da9-7916d48a21dd
Russell, Andrea E.
b6b7c748-efc1-4d5d-8a7a-8e4b69396169
Skylaris, Chris-Kriton
8f593d13-3ace-4558-ba08-04e48211af61
Verga, Lucas Garcia
681e0d2b-083d-4478-85f6-d2eca7673c24
Aarons, Jolyon
93e68133-73b0-43e0-8c91-464920f4a503
Sarwar, M
75fc6212-1ca1-4733-bab0-0fae948ecc4d
Thompsett, D.
6f7014d2-14b6-401e-9da9-7916d48a21dd
Russell, Andrea E.
b6b7c748-efc1-4d5d-8a7a-8e4b69396169
Skylaris, Chris-Kriton
8f593d13-3ace-4558-ba08-04e48211af61

Verga, Lucas Garcia, Aarons, Jolyon, Sarwar, M, Thompsett, D., Russell, Andrea E. and Skylaris, Chris-Kriton (2018) DFT calculation of oxygen adsorption on platinum nanoparticles: coverage and size effects. Faraday Discussions, 1-15. (doi:10.1039/C7FD00218A).

Record type: Article

Abstract

Catalysts made of Pt nanoparticles and Pt alloys are considered state-of-the-art catalysts for the anodic and cathodic reactions involved in hydrogen fuel cells. The optimal size of such nanoparticles for each chemical reaction is an unsolved problem, which depends on environmental variables, such as reactant concentration, solvent, temperature, etc. From a theoretical point of view, this problem has been tackled mainly by observing how single key adsorbates react with different nanoparticles in controlled conditions. In this work, we use large-scale DFT calculations to examine the interplay between the Pt nanoparticle size and O coverage effects. We examine single O adsorptions for three adsorption sites on cuboctahedral platinum nanoparticles with different sizes. As we grow the nanoparticle size, the binding strength decreases and we observed a quick convergence of the adsorption energies with increasing nanoparticle size, which correlates with the calculated d-band centre for (111) Pt facets on such nanoparticles. We also carried out a detailed study of the effect of oxygen coverage with varying fractions of O monolayer coverage, computing adsorption energies per O atom for Pt 55 , Pt 147, and Pt309 nanoparticles with several O coverages. In general, the increase of O coverage led to weaker adsorption energies per O atom, and when analysing the results in terms of oxygen monolayers, this effect is more pronounced for larger nanoparticles. The O coverage dependency of the adsorption energy per O atom is analysed in terms of the O distribution for each nanoparticle size and electronic changes that the adsorbed oxygen causes to the Pt nanoparticle. In studying nanoparticle size and oxygen coverage effects simultaneously, we offer insights with DFT accuracy to help on heterogeneous catalyst design

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faraday_discussions_o_on_pt_size-coverage_submitted2017_12_18 - Accepted Manuscript
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Accepted/In Press date: 3 January 2018
e-pub ahead of print date: 3 January 2018

Identifiers

Local EPrints ID: 417183
URI: https://eprints.soton.ac.uk/id/eprint/417183
ISSN: 0301-7249
PURE UUID: 0f34c4a5-485c-4b73-94ef-2c93dcbf1403
ORCID for Andrea E. Russell: ORCID iD orcid.org/0000-0002-8382-6443
ORCID for Chris-Kriton Skylaris: ORCID iD orcid.org/0000-0003-0258-3433

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Date deposited: 24 Jan 2018 17:30
Last modified: 14 Mar 2019 05:17

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Contributors

Author: Lucas Garcia Verga
Author: Jolyon Aarons
Author: M Sarwar
Author: D. Thompsett

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