Exploring the complexity of nanostructured catalysts with computational chemistry methods
[eng] Heterogeneous catalysis relies on interactions with a material’s surface to lower the energy barrier of chemical reactions, thus increasing their rate. Enhancing catalytic performance typically involves nanoscale surface modifications designed to increase the density of active sites and tailor...
| Autor: | |
|---|---|
| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2025 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/223698 |
| Acceso en línea: | https://hdl.handle.net/2445/223698 http://hdl.handle.net/10803/695509 |
| Access Level: | acceso abierto |
| Palabra clave: | Química quàntica Catàlisi heterogènia Òxids metàl·lics Materials nanoestructurats Quantum chemistry Heterogeneus catalysis Metallic oxides Nanostructured materials |
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España |
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| dc.title.none.fl_str_mv |
Exploring the complexity of nanostructured catalysts with computational chemistry methods |
| title |
Exploring the complexity of nanostructured catalysts with computational chemistry methods |
| spellingShingle |
Exploring the complexity of nanostructured catalysts with computational chemistry methods Castro Latorre, Pablo Química quàntica Catàlisi heterogènia Òxids metàl·lics Materials nanoestructurats Quantum chemistry Heterogeneus catalysis Metallic oxides Nanostructured materials |
| title_short |
Exploring the complexity of nanostructured catalysts with computational chemistry methods |
| title_full |
Exploring the complexity of nanostructured catalysts with computational chemistry methods |
| title_fullStr |
Exploring the complexity of nanostructured catalysts with computational chemistry methods |
| title_full_unstemmed |
Exploring the complexity of nanostructured catalysts with computational chemistry methods |
| title_sort |
Exploring the complexity of nanostructured catalysts with computational chemistry methods |
| dc.creator.none.fl_str_mv |
Castro Latorre, Pablo |
| author |
Castro Latorre, Pablo |
| author_facet |
Castro Latorre, Pablo |
| author_role |
author |
| dc.contributor.none.fl_str_mv |
Neyman, Konstantin M. Bruix Fusté, Albert Universitat de Barcelona. Facultat de Química |
| dc.subject.none.fl_str_mv |
Química quàntica Catàlisi heterogènia Òxids metàl·lics Materials nanoestructurats Quantum chemistry Heterogeneus catalysis Metallic oxides Nanostructured materials |
| topic |
Química quàntica Catàlisi heterogènia Òxids metàl·lics Materials nanoestructurats Quantum chemistry Heterogeneus catalysis Metallic oxides Nanostructured materials |
| description |
[eng] Heterogeneous catalysis relies on interactions with a material’s surface to lower the energy barrier of chemical reactions, thus increasing their rate. Enhancing catalytic performance typically involves nanoscale surface modifications designed to increase the density of active sites and tailor their geometric and electronic structures at the atomic level, thereby optimizing adsorption energies, reaction intermediates stabilization, and turnover frequencies. However, the structural complexity of nanostructured multi-component catalysts precludes their understanding and rational improvement. The work presented in this thesis studies different types of technologically relevant nanostructured ceria-based catalysts varying in shape, composition, size and dimensionality. Computational simulations are used to understand the effect of the interaction of different nanostructures with CeO2 surfaces and elucidate their physical and chemical properties. First, metallic Pt clusters supported on CeO2 are studied to address the effects of electron transfer between metal particles and reducible oxides (known as Electronic Metal Support Interactions - EMSI) on the chemical properties of a Pt8 cluster. A computational strategy is proposed and critically evaluated to systematically characterize the electron transfer process and the different possible resulting electronic states. The chemical properties of the different sites and electronic states of the supported Pt8 cluster are evaluated, revealing significant effects in calculated adsorption energies due to EMSI for various reactants and intermediates. Second, the structural and electronic properties of the interface between a 2D FeO monolayer and the CeO2(111) surface are investigated. Simulations reveal a corrugated interfacial geometry, structure, consistent with experimental observations of periodic nanostructures. The electronic structure analysis indicates the presence of multiple electronic states, exhibiting an intricate interplay between the Fe2+/Fe3+ - Ce4+/Ce3+ redox couples. These calculations also reveal the importance of dispersion interactions and oxygen adsorption in the stabilization of periodic FeOx 2D nanostructures. Finally, the chemical reactivity of an oxidized Pt6O9 cluster supported on CeO2 is investigated to rationalize the high catalytic activity of oxidized ceria-supported Pt particles towards the CO oxidation reaction below room temperature. Activation energies of CO oxidation on the Pt6O9 cluster suggest that both the oxidized cluster and gas-phase O2 are the main sources of O atoms for CO2 formation. A reaction mechanism is proposed for the reaction on the Pt6O9 cluster where the CeO2 support acts as a spectator for the described catalytic cycles. Kinetic Monte Carlo simulations show the proposed mechanism to be consistent with high catalytic activity of Pt oxide clusters below room temperature. |
| publishDate |
2025 |
| dc.date.none.fl_str_mv |
2025 |
| dc.type.none.fl_str_mv |
info:eu-repo/semantics/doctoralThesis info:eu-repo/semantics/publishedVersion |
| format |
doctoralThesis |
| status_str |
publishedVersion |
| dc.identifier.none.fl_str_mv |
https://hdl.handle.net/2445/223698 http://hdl.handle.net/10803/695509 |
| url |
https://hdl.handle.net/2445/223698 http://hdl.handle.net/10803/695509 |
| dc.language.none.fl_str_mv |
Inglés |
| language_invalid_str_mv |
Inglés |
| dc.rights.none.fl_str_mv |
cc by (c) Castro Latorre, Pablo, 2025 http://creativecommons.org/licenses/by/3.0/es/ info:eu-repo/semantics/openAccess |
| rights_invalid_str_mv |
cc by (c) Castro Latorre, Pablo, 2025 http://creativecommons.org/licenses/by/3.0/es/ |
| eu_rights_str_mv |
openAccess |
| dc.format.none.fl_str_mv |
application/pdf |
| dc.publisher.none.fl_str_mv |
Universitat de Barcelona |
| publisher.none.fl_str_mv |
Universitat de Barcelona |
| dc.source.none.fl_str_mv |
Tesis Doctorals - Facultat - Química reponame:Dipòsit Digital de la UB instname:Universidad de Barcelona |
| instname_str |
Universidad de Barcelona |
| reponame_str |
Dipòsit Digital de la UB |
| collection |
Dipòsit Digital de la UB |
| repository.name.fl_str_mv |
|
| repository.mail.fl_str_mv |
|
| _version_ |
1869418020279943168 |
| spelling |
Exploring the complexity of nanostructured catalysts with computational chemistry methodsCastro Latorre, PabloQuímica quànticaCatàlisi heterogèniaÒxids metàl·licsMaterials nanoestructuratsQuantum chemistryHeterogeneus catalysisMetallic oxidesNanostructured materials[eng] Heterogeneous catalysis relies on interactions with a material’s surface to lower the energy barrier of chemical reactions, thus increasing their rate. Enhancing catalytic performance typically involves nanoscale surface modifications designed to increase the density of active sites and tailor their geometric and electronic structures at the atomic level, thereby optimizing adsorption energies, reaction intermediates stabilization, and turnover frequencies. However, the structural complexity of nanostructured multi-component catalysts precludes their understanding and rational improvement. The work presented in this thesis studies different types of technologically relevant nanostructured ceria-based catalysts varying in shape, composition, size and dimensionality. Computational simulations are used to understand the effect of the interaction of different nanostructures with CeO2 surfaces and elucidate their physical and chemical properties. First, metallic Pt clusters supported on CeO2 are studied to address the effects of electron transfer between metal particles and reducible oxides (known as Electronic Metal Support Interactions - EMSI) on the chemical properties of a Pt8 cluster. A computational strategy is proposed and critically evaluated to systematically characterize the electron transfer process and the different possible resulting electronic states. The chemical properties of the different sites and electronic states of the supported Pt8 cluster are evaluated, revealing significant effects in calculated adsorption energies due to EMSI for various reactants and intermediates. Second, the structural and electronic properties of the interface between a 2D FeO monolayer and the CeO2(111) surface are investigated. Simulations reveal a corrugated interfacial geometry, structure, consistent with experimental observations of periodic nanostructures. The electronic structure analysis indicates the presence of multiple electronic states, exhibiting an intricate interplay between the Fe2+/Fe3+ - Ce4+/Ce3+ redox couples. These calculations also reveal the importance of dispersion interactions and oxygen adsorption in the stabilization of periodic FeOx 2D nanostructures. Finally, the chemical reactivity of an oxidized Pt6O9 cluster supported on CeO2 is investigated to rationalize the high catalytic activity of oxidized ceria-supported Pt particles towards the CO oxidation reaction below room temperature. Activation energies of CO oxidation on the Pt6O9 cluster suggest that both the oxidized cluster and gas-phase O2 are the main sources of O atoms for CO2 formation. A reaction mechanism is proposed for the reaction on the Pt6O9 cluster where the CeO2 support acts as a spectator for the described catalytic cycles. Kinetic Monte Carlo simulations show the proposed mechanism to be consistent with high catalytic activity of Pt oxide clusters below room temperature.[cat] La catàlisi heterogènia es basa en les interaccions amb la superfície d’un material per reduir la barrera energètica de les reaccions químiques, incrementant així la seva velocitat. Millorar el rendiment catalític normalment implica modificacions a escala nanoscòpica de la superfície, aquestes són dissenyades per augmentar la densitat dels centres actius i ajustar les seves estructures geomètriques i electròniques a escala atòmica, optimitzant així les energies d’adsorció, l’estabilització dels intermediaris de reacció i el nombre de recanvi. No obstant això, la complexitat estructural dels catalitzadors nanoestructurats multicomponents dificulta la seva comprensió i millora racional. El treball presentat en aquesta tesi estudia diferents tipus de catalitzadors nanoestructurats tecnològicament rellevants basats en cèria, amb diverses formes, composicions, mides i dimensionalitat. S’empren simulacions computacionals per comprendre l’efecte de la interacció de diferents nanoestructures amb superfícies de CeO₂ i per determinar-ne les propietats físiques i químiques. En primer lloc, s’estudien clústers metàl·lics de Pt suportats sobre CeO₂ per analitzar els efectes de la transferència electrònica entre partícules metàl·liques i òxids reduïbles (coneguts com a Interaccions Electròniques Metall-Suport - EMSI) sobre les propietats químiques d’un clúster de Pt₈. Es proposa i s’avalua críticament una estratègia computacional per caracteritzar sistemàticament el procés de transferència electrònica i els diferents estats electrònics resultants possibles. S’avaluen les propietats químiques dels diferents centres actius i estats electrònics del clúster de Pt₈ suportat, denotant efectes significatius en les energies d’adsorció calculades a causa de les EMSI per a diversos reactius i intermediaris. En segon lloc, s’investiguen les propietats estructurals i electròniques de la interfície entre una monocapa de FeO 2D i la superfície CeO₂(111). Les simulacions mostren una geometria interficial ondulada, consistent amb les observacions experimentals de nanostructures periòdiques. L’anàlisi de l’estructura electrònica indica la presència de múltiples estats electrònics, assenyalant una interacció complexa entre els parells redox Fe²⁺/Fe³⁺ - Ce⁴⁺/Ce³⁺. Aquests càlculs també revelen la importància de les interaccions de dispersió i de l’adsorció d’oxigen en l’estabilització de nanostructures 2D periòdiques de FeOₓ. Finalment, s’estudia la reactivitat química d’un clúster oxidat Pt₆O₉ suportat sobre CeO₂ per copsar l’elevada activitat catalítica de partícules de Pt oxidat suportades sobre cèria en la reacció d’oxidació de CO per sota de la temperatura ambient. Les energies d’activació de l’oxidació de CO sobre el clúster Pt₆O₉ suggereixen que tant el clúster oxidat com l’O₂ en fase gasosa són les principals fonts d’àtoms d’oxigen per a la formació de CO₂. Es proposa un mecanisme per a la reacció sobre el clúster Pt₆O₉ on el suport de CeO₂ actua com a espectador dels cicles catalítics descrits. Simulacions cinètiques de Monte Carlo mostren que el mecanisme proposat és consistent amb l’alta activitat catalítica dels clústers d’òxid de Pt per sota de la temperatura ambient.Universitat de BarcelonaNeyman, Konstantin M.Bruix Fusté, AlbertUniversitat de Barcelona. Facultat de Química2025info:eu-repo/semantics/doctoralThesisinfo:eu-repo/semantics/publishedVersionapplication/pdfhttps://hdl.handle.net/2445/223698http://hdl.handle.net/10803/695509Tesis Doctorals - Facultat - Químicareponame:Dipòsit Digital de la UBinstname:Universidad de BarcelonaIngléscc by (c) Castro Latorre, Pablo, 2025http://creativecommons.org/licenses/by/3.0/es/info:eu-repo/semantics/openAccessoai:diposit.ub.edu:2445/2236982026-05-27T06:46:51Z |
| score |
15.81155 |