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* old and bolonia study programme


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ORR stability of Mn–Co/polypyrrole nanocomposite electrocatalysts studied by quasi in-situ identical-location photoelectron microspectroscopy
Maya Kiskinova, Claudio Mele, Hikmet Sezen, Benedetto Bozzini, Mattia Fanetti, Andrea Goldoni, Luca Gregoratti, Belen Aleman, Matteo Amati, Patrizia Bocchetta, 2016, original scientific article

Abstract: The stability of pyrolyzed Mn–Co/polypyrrole (PPy) nanocomposites towards the Oxygen Reduction Reaction (ORR) in alkaline solution, was studied with a close-knit group of complementary microscopic and space-resolved spectroscopic approaches: Atomic Force Microscopy (AFM), Scanning and High-Resolution Transmission Electron Microscopy (SEM, HRTEM) and identical-location Scanning PhotoElectron Microscopy (SPEM). Tracking quasi-in situ the morphochemical evolution of the Mn–Co/PPy catalyst upon electrochemical aging under ORR conditions by this multi-technique approach, has allowed to clarify the key physico-chemical processes underlying the dramatic impact of Co additions to stability improvement.
Found in: ključnih besedah
Summary of found: ...of pyrolyzed Mn–Co/polypyrrole (PPy) nanocomposites towards the Oxygen Reduction Reaction (ORR) in alkaline solution, was studied...
Keywords: Mixed manganese oxides, Polypyrrole, Oxygen reduction, Electrocatalysis, Nanocomposites, X-ray photoelectron microspectroscopy
Published: 25.07.2016; Views: 2118; Downloads: 0
.pdf Fulltext (1,36 MB)

Chemical and sensory study on the evolution of aromatic and nonaromatic compounds during the progressive oxidative storage of a Sauvignon blanc wine
Wessel Johannes Du Toit, Antonio C. Silva Ferreira, katja Šuklje, Elizma Van Wyngaard, Carien Coetzee, 2016, original scientific article

Found in: ključnih besedah
Summary of found: ...Sauvignon blanc, oxygen, wine aroma, sensory...
Keywords: Sauvignon blanc, oxygen, wine aroma, sensory
Published: 06.12.2016; Views: 2117; Downloads: 0
.pdf Fulltext (2,02 MB)

Blaž Winkler, doctoral dissertation

Abstract: This work is primarily focused on application of standard first-principle computational approaches to model oxygen excess related point defects in amorphous silica. Atomic models with their respective electronic and optical properties are explored together with some conversion mechanisms between defect models. The first chapter overviews extensive literature about the already known properties of oxygen related defects. Second chapter briefly introduces main methods that have been used in this research, in particular Density Functional Theory (DFT) as energy and force engine with short description of minimal energy path (MEP) algorithm used for modeling chemical/migration reactions, GW approximation for charged electronic excitations (band structure) and Bethe-Salpeter Equation (BSE) for neutral excitations (optical absorption and excitonic structure including electron hole interaction). The third chapter is devoted to the presentation of results. Thanks to the calculation of optical properties of peroxy bridge (POL), a correlation has been found between structural disorder, specifically dihedral angle dispersion, and low coupling with light, which has been identified as main reason why no clear absorption bands have been assigned to the POL. Structure and stability of some other defects, like interstitial ozone molecule (ozonyl) and dioxasilirane (silicon analogy of dioxirane), have been studied. These defects are usually not considered as most important species, however their calculated formation energies are lower compared to some known defects, which indicates they might be present in silica. From a detailed study on possible reaction mechanisms, it has been found that ozonyl might be one of the most important intermediate steps for oxygen exchange reactions. Results also show that dioxasilirane can be spontaneously created during the interaction of oxygen with lone pair defects. By exploring different reactions between oxygen and pre-existing oxygen deficiency centers (ODCs), calculations predict two kinds of passivation behaviors: single-barrier reversible mechanisms with the formation of dioxasilirane-like groups, for which the network keeps the memory of the precursory lone pair defects, and single or multiple-barrier mechanisms, for which the network loses its memory, either because of the high reverse barrier or because of a reconstruction. Final part of this research has been devoted to experimental characterization of the response and tolerance of optical fibers loaded with oxygen under irradiation. These include experiments on commercial fiber along with canonical samples (Optical fibers developed with the intention of studying correlations between different fabrication parameters, dopant/impurity concentration and doping concentrations). Studied fibers also include rare-earth doped fibers.
Found in: ključnih besedah
Keywords: Silica, DFT, GW-approximation, Bethe-Salpeter equation, NEB, defect, oxygen, oxygen excess centers, oxygen deficiency centers, optical absorption, optical fibers, radiation induced attenuation.
Published: 07.05.2019; Views: 783; Downloads: 50
.pdf Fulltext (13,18 MB)

Learning from Nature: Charge Transfer and Carbon Dioxide Activation at Single, Biomimetic Fe Sites in Tetrapyrroles on Graphene
Erik Vesselli, Nicola Seriani, Maria Peressi, Cinzia Cepek, Matteo Rinaldi, Erika Tomsič, Fatema Mohamed, Manuel Corva, 2019, original scientific article

Found in: ključnih besedah
Summary of found: ...carbon dioxide, phthalocyanines, graphene, oxygen, Dirac cones...
Keywords: carbon dioxide, phthalocyanines, graphene, oxygen, Dirac cones
Published: 03.12.2019; Views: 334; Downloads: 0
.pdf Fulltext (2,66 MB)

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