Interaction of SO<sub>2</sub> with the Platinum (001), (011), and (111) Surfaces: A DFT Study

Given the importance of SO<sub>2</sub> as a pollutant species in the environment and its role in the hybrid sulphur (HyS) cycle for hydrogen production, we carried out a density functional theory study of its interaction with the Pt (001), (011), and (111) surfaces. First, we investigate...

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Main Authors: Marietjie J. Ungerer, David Santos-Carballal, Abdelaziz Cadi-Essadek, Cornelia G. C. E. van Sittert, Nora H. de Leeuw
Format: Article
Language:English
Published: MDPI AG 2020-05-01
Series:Catalysts
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Online Access:https://www.mdpi.com/2073-4344/10/5/558
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author Marietjie J. Ungerer
David Santos-Carballal
Abdelaziz Cadi-Essadek
Cornelia G. C. E. van Sittert
Nora H. de Leeuw
author_facet Marietjie J. Ungerer
David Santos-Carballal
Abdelaziz Cadi-Essadek
Cornelia G. C. E. van Sittert
Nora H. de Leeuw
author_sort Marietjie J. Ungerer
collection DOAJ
description Given the importance of SO<sub>2</sub> as a pollutant species in the environment and its role in the hybrid sulphur (HyS) cycle for hydrogen production, we carried out a density functional theory study of its interaction with the Pt (001), (011), and (111) surfaces. First, we investigated the adsorption of a single SO<sub>2</sub> molecule on the three Pt surfaces. On both the (001) and (111) surfaces, the SO<sub>2</sub> had a S,O-bonded geometry, while on the (011) surface, it had a co-pyramidal and bridge geometry. The largest adsorption energy was obtained on the (001) surface (<i>E<sub>ads</sub></i> = −2.47 eV), followed by the (011) surface (<i>E<sub>ads</sub></i> = −2.39 and −2.28 eV for co-pyramidal and bridge geometries, respectively) and the (111) surface (<i>E<sub>ads</sub></i> = −1.85 eV). When the surface coverage was increased up to a monolayer, we noted an increase of <i>E<sub>ads</sub></i>/SO<sub>2</sub> for all the surfaces, but the (001) surface remained the most favourable overall for SO<sub>2</sub> adsorption. On the (111) surface, we found that when the surface coverage was θ > 0.78, two neighbouring SO<sub>2</sub> molecules reacted to form SO and SO<sub>3</sub>. Considering the experimental conditions, we observed that the highest coverage in terms of the number of SO<sub>2</sub> molecules per metal surface area was (111) > (001) > (011). As expected, when the temperature increased, the surface coverage decreased on all the surfaces, and gradual desorption of SO<sub>2</sub> would occur above 500 K. Total desorption occurred at temperatures higher than 700 K for the (011) and (111) surfaces. It was seen that at 0 and 800 K, only the (001) and (111) surfaces were expressed in the morphology, but at 298 and 400 K, the (011) surface was present as well. Taking into account these data and those from a previous paper on water adsorption on Pt, it was evident that at temperatures between 400 and 450 K, where the HyS cycle operates, most of the water would desorb from the surface, thereby increasing the SO<sub>2</sub> concentration, which in turn may lead to sulphur poisoning of the catalyst.
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spelling doaj.art-ec68d5cdc25a4e21ad439f20ca5fb87d2023-11-20T00:52:15ZengMDPI AGCatalysts2073-43442020-05-0110555810.3390/catal10050558Interaction of SO<sub>2</sub> with the Platinum (001), (011), and (111) Surfaces: A DFT StudyMarietjie J. Ungerer0David Santos-Carballal1Abdelaziz Cadi-Essadek2Cornelia G. C. E. van Sittert3Nora H. de Leeuw4Laboratory for Applied Molecular Modelling, Research Focus Area: Chemical Resource Beneficiation, North-West University, Private Bag X6001, Potchefstroom 2520, South AfricaSchool of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UKSchool of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UKLaboratory for Applied Molecular Modelling, Research Focus Area: Chemical Resource Beneficiation, North-West University, Private Bag X6001, Potchefstroom 2520, South AfricaSchool of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UKGiven the importance of SO<sub>2</sub> as a pollutant species in the environment and its role in the hybrid sulphur (HyS) cycle for hydrogen production, we carried out a density functional theory study of its interaction with the Pt (001), (011), and (111) surfaces. First, we investigated the adsorption of a single SO<sub>2</sub> molecule on the three Pt surfaces. On both the (001) and (111) surfaces, the SO<sub>2</sub> had a S,O-bonded geometry, while on the (011) surface, it had a co-pyramidal and bridge geometry. The largest adsorption energy was obtained on the (001) surface (<i>E<sub>ads</sub></i> = −2.47 eV), followed by the (011) surface (<i>E<sub>ads</sub></i> = −2.39 and −2.28 eV for co-pyramidal and bridge geometries, respectively) and the (111) surface (<i>E<sub>ads</sub></i> = −1.85 eV). When the surface coverage was increased up to a monolayer, we noted an increase of <i>E<sub>ads</sub></i>/SO<sub>2</sub> for all the surfaces, but the (001) surface remained the most favourable overall for SO<sub>2</sub> adsorption. On the (111) surface, we found that when the surface coverage was θ > 0.78, two neighbouring SO<sub>2</sub> molecules reacted to form SO and SO<sub>3</sub>. Considering the experimental conditions, we observed that the highest coverage in terms of the number of SO<sub>2</sub> molecules per metal surface area was (111) > (001) > (011). As expected, when the temperature increased, the surface coverage decreased on all the surfaces, and gradual desorption of SO<sub>2</sub> would occur above 500 K. Total desorption occurred at temperatures higher than 700 K for the (011) and (111) surfaces. It was seen that at 0 and 800 K, only the (001) and (111) surfaces were expressed in the morphology, but at 298 and 400 K, the (011) surface was present as well. Taking into account these data and those from a previous paper on water adsorption on Pt, it was evident that at temperatures between 400 and 450 K, where the HyS cycle operates, most of the water would desorb from the surface, thereby increasing the SO<sub>2</sub> concentration, which in turn may lead to sulphur poisoning of the catalyst.https://www.mdpi.com/2073-4344/10/5/558sulphur dioxideSO<sub>2</sub>platinumadsorptionDFT
spellingShingle Marietjie J. Ungerer
David Santos-Carballal
Abdelaziz Cadi-Essadek
Cornelia G. C. E. van Sittert
Nora H. de Leeuw
Interaction of SO<sub>2</sub> with the Platinum (001), (011), and (111) Surfaces: A DFT Study
Catalysts
sulphur dioxide
SO<sub>2</sub>
platinum
adsorption
DFT
title Interaction of SO<sub>2</sub> with the Platinum (001), (011), and (111) Surfaces: A DFT Study
title_full Interaction of SO<sub>2</sub> with the Platinum (001), (011), and (111) Surfaces: A DFT Study
title_fullStr Interaction of SO<sub>2</sub> with the Platinum (001), (011), and (111) Surfaces: A DFT Study
title_full_unstemmed Interaction of SO<sub>2</sub> with the Platinum (001), (011), and (111) Surfaces: A DFT Study
title_short Interaction of SO<sub>2</sub> with the Platinum (001), (011), and (111) Surfaces: A DFT Study
title_sort interaction of so sub 2 sub with the platinum 001 011 and 111 surfaces a dft study
topic sulphur dioxide
SO<sub>2</sub>
platinum
adsorption
DFT
url https://www.mdpi.com/2073-4344/10/5/558
work_keys_str_mv AT marietjiejungerer interactionofsosub2subwiththeplatinum001011and111surfacesadftstudy
AT davidsantoscarballal interactionofsosub2subwiththeplatinum001011and111surfacesadftstudy
AT abdelazizcadiessadek interactionofsosub2subwiththeplatinum001011and111surfacesadftstudy
AT corneliagcevansittert interactionofsosub2subwiththeplatinum001011and111surfacesadftstudy
AT norahdeleeuw interactionofsosub2subwiththeplatinum001011and111surfacesadftstudy