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Searching for the thermodynamic limit - a DFT study of the step-wise water oxidation of the bipyramidal Cu-7 cluster
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.ORCID iD: 0000-0003-3832-2331
Swedish Nuclear Fuel and Waste Management Co (SKB).
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.ORCID iD: 0000-0003-2673-075X
2014 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, no 6, 2452-2464 p.Article in journal (Refereed) Published
Abstract [en]

Oxidative degradation of copper in aqueous environments is a major concern in areas such as catalysis, electronics and construction engineering. A particular challenge is to systematically investigate the details of this process for non-ideal copper surfaces and particles under the conditions found in most real applications. To this end, we have used hybrid density functional theory to study the oxidation of a Cu-7 cluster in water solution. Especially, the role of a large water coverage is explored. This has resulted in the conclusion that, under atmospheric H-2 pressures, the thermodynamically most favored state of degradation is achieved upon the generation of four H-2 molecules (i.e. Cu-7 + 8H(2)O -> Cu-7(OH)(8) + 4H(2)) in both condensed and gas phases. This state corresponds to an average oxidation state below Cu(I). The calculations suggest that the oxidation reaction is slow at ambient temperatures with the water dissociation as the rate-limiting step. Our findings are expected to have implication for, among other areas, the copper catalyzed water-gas shift reaction, and for the general understanding of copper corrosion in aqueous environments.

Place, publisher, year, edition, pages
2014. Vol. 16, no 6, 2452-2464 p.
Keyword [en]
Gas Shift Reaction, Small Copper Clusters, Continuum Dielectric Theory, Solvation Free-Energies, Near-Ambient Conditions, Ab-Initio, Dissociative Adsorption, Structure Sensitivity, Hyperfine-Structure, Fundamental-Aspects
National Category
Physical Sciences Chemical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-141318DOI: 10.1039/c3cp53865fISI: 000329926700032Scopus ID: 2-s2.0-84892606991OAI: oai:DiVA.org:kth-141318DiVA: diva2:696514
Note

QC 20140214

Available from: 2014-02-14 Created: 2014-02-13 Last updated: 2017-12-06Bibliographically approved
In thesis
1. Computational Studies of Chemical Interactions: Molecules, Surfaces and Copper Corrosion
Open this publication in new window or tab >>Computational Studies of Chemical Interactions: Molecules, Surfaces and Copper Corrosion
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The chemical bond – a corner stone in science and a prerequisite for life – is the focus of this thesis. Fundamental and applied aspects of chemical bonding are covered including the development of new computational methods for the characterization and rationalization of chemical interactions. The thesis also covers the study of corrosion of copper-based materials. The latter is motivated by the proposed use of copper as encapsulating material for spent nuclear fuel in Sweden.

In close collaboration with experimental groups, state-of-the-art computational methods were employed for the study of chemistry at the atomic scale. First, oxidation of nanoparticulate copper was examined in anoxic aqueous media in order to better understand the copper-water thermodynamics in relation to the corrosion of copper material under oxygen free conditions. With a similar ambition, the water-cuprite interface was investigated with regards to its chemical composition and reactivity. This was compared to the behavior of methanol and hydrogen sulfide at the cuprite surface.

An overall ambition during the development of computational methods for the analysis of chemical bonding was to bridge the gap between molecular and materials chemistry. Theory and results are thus presented and applied in both a molecular and a solid-state framework. A new property, the local electron attachment energy, for the characterization of a compound’s local electrophilicity was introduced. Together with the surface electrostatic potential, the new property predicts and rationalizes regioselectivity and trends of molecular reactions, and interactions on metal and oxide nanoparticles and extended surfaces.

Detailed atomistic understanding of chemical processes is a prerequisite for the efficient development of chemistry. We therefore envisage that the results of this thesis will find widespread use in areas such as heterogeneous catalysis, drug discovery, and nanotechnology.

Abstract [sv]

Den kemiska bindningen – en hörnsten inom naturvetenskapen och oumbärlig för allt liv – är det centrala temat i den här avhandlingen. Både grundläggande och tillämpade aspekter behandlas. Detta inkluderar utvecklingen av nya beräkningsmetoder för förståelse och karaktärisering av kemiska interaktioner. Dessutom behandlas korrosion av kopparbaserade material. Det sistnämnda är motiverat av förslaget att använda koppar som inkapslingsmaterial för hanteringen av kärnavfall i Sverige.

Kvantkemiska beräkningsmetoder enligt state-of-the-art har använts för att studera kemi på atomnivå, detta i nära sammabete med experimentella grupper. Initialt studerades oxidation av kopparnanopartiklar under syrgasfria och vattenrika förhållanden. Detta för att bättre kartlägga koppar-vattensystemets termodynamik. Av samma orsak detaljstuderades även gränsskiktet mellan vatten och kuprit med fokus på dess kemiska sammansättning och reaktivitet. Resultaten har jämförts med metanols och vätesulfids kemiska beteende på ytan av kuprit.

En övergripande målsättningen under arbetet med att utveckla nya beräkningsbaserade analysverktyg för kemiska bindningar har varit att överbrygga gapet mellan molekylär- och materialkemi. Därför presenteras teoretiska aspekter samt tillämpningar från både ett molekylärt samt ett fast-fas perspektiv. En ny deskriptor för karaktärisering av föreningars lokala elektrofilicitet har introducerats – den lokala elektronadditionsenergin. Tillsammans med den elektrostatiska potentialen uppvisar den nya deskriptorn förmåga att förutsäga samt förklara regioselektivitet och trender för molekylära reaktioner, och för interaktioner på metal- och oxidbaserade nanopartiklar och ytor.

En detaljerad förståelse av kemiska processer på atomnivå är en nödvändighet för ett effektivt utvecklande av kemivetenskapen. Vi förutspår därför att resultaten från den här avhandlingen kommer att få omfattande användning inom områden som heterogen katalys, läkemedelsdesign och nanoteknologi.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2017. 143 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2017:35
Keyword
computational chemistry, density functional theory, chemical interactions, reactivity descriptors, copper corrosion, surface and materials science, nucleophilic substitution reactions, heterogeneous catalysis, transition metal oxides, nanotechnology, beräkningskemi, täthetsfunktionalteori, kemiska interaktioner, reaktivitetsdeskriptorer, kopparkorrosion, yt- och materialvetenskap, nukleofila substitutionsreaktioner, heterogen katalys, överångsmetalloxider, nanoteknologi
National Category
Chemical Sciences Materials Chemistry Organic Chemistry Physical Chemistry Theoretical Chemistry
Research subject
Chemistry
Identifiers
urn:nbn:se:kth:diva-213028 (URN)978-91-7729-506-8 (ISBN)
Public defence
2017-09-29, F3 (rumsnr: 132), Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20170829

Available from: 2017-08-29 Created: 2017-08-28 Last updated: 2017-08-29Bibliographically approved

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Halldin Stenlid, JoakimBrinck, Tore

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