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Designing new renewable nano-structured electrode and membrane materials for direct alkaline ethanol fuel cell
De Chen, Jia Yang, Jørgen Svendby, Qingjun Chen, Gvido Bratina, EGON PAVLICA, Ji-Song Huang, Jessie Lue Shingjiang, 2020, končno poročilo o rezultatih raziskav

Najdeno v: ključnih besedah
Povzetek najdenega: ...fuel cell, ethanol oxidation, graphene, oxygen reduction, catalyst, pt-free, electrochemical impedance spectroscopy...
Ključne besede: fuel cell, ethanol oxidation, graphene, oxygen reduction, catalyst, pt-free, electrochemical impedance spectroscopy
Objavljeno: 03.12.2020; Ogledov: 104; Prenosov: 0
.pdf Polno besedilo (5,31 MB)

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, izvirni znanstveni članek

Opis: 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.
Najdeno v: ključnih besedah
Povzetek najdenega: ...of pyrolyzed Mn–Co/polypyrrole (PPy) nanocomposites towards the Oxygen Reduction Reaction (ORR) in alkaline solution, was studied...
Ključne besede: Mixed manganese oxides, Polypyrrole, Oxygen reduction, Electrocatalysis, Nanocomposites, X-ray photoelectron microspectroscopy
Objavljeno: 25.07.2016; Ogledov: 2540; Prenosov: 0
.pdf Polno besedilo (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, izvirni znanstveni članek

Najdeno v: ključnih besedah
Povzetek najdenega: ...Sauvignon blanc, oxygen, wine aroma, sensory...
Ključne besede: Sauvignon blanc, oxygen, wine aroma, sensory
Objavljeno: 06.12.2016; Ogledov: 2494; Prenosov: 0
.pdf Polno besedilo (2,02 MB)

Blaž Winkler, doktorska disertacija

Opis: 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.
Najdeno v: ključnih besedah
Ključne besede: Silica, DFT, GW-approximation, Bethe-Salpeter equation, NEB, defect, oxygen, oxygen excess centers, oxygen deficiency centers, optical absorption, optical fibers, radiation induced attenuation.
Objavljeno: 07.05.2019; Ogledov: 1214; Prenosov: 73
.pdf Polno besedilo (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, izvirni znanstveni članek

Najdeno v: ključnih besedah
Povzetek najdenega: ...carbon dioxide, phthalocyanines, graphene, oxygen, Dirac cones...
Ključne besede: carbon dioxide, phthalocyanines, graphene, oxygen, Dirac cones
Objavljeno: 03.12.2019; Ogledov: 743; Prenosov: 0
.pdf Polno besedilo (2,66 MB)

Effect of the Morphology of the High-Surface-Area Support on the Performance of the Oxygen-Evolution Reaction for Iridium Nanoparticles
Leonard Moriau, Marjan Bele, Živa Marinko, Francisco Ruiz-Zepeda, Gorazd Koderman, Martin Šala, Angelija Kjara Šurca, Janez Kovač, Iztok Arčon, Primož Jovanovič, Nejc Hodnik, Luka Suhadolnik, 2021, izvirni znanstveni članek

Opis: The development of affordable, low-iridium-loading, scalable, active, and stable catalysts for the oxygen-evolution reaction (OER) is a requirement for the commercialization of proton-exchange membrane water electrolyzers (PEMWEs). However, the synthesis of high-performance OER catalysts with minimal use of the rare and expensive element Ir is very challenging and requires the identification of electrically conductive and stable high-surface-area support materials. We developed a synthesis procedure for the production of large quantities of a nanocomposite powder containing titanium oxynitride (TiONx) and Ir. The catalysts were synthesized with an anodic oxidation process followed by detachment, milling, thermal treatment, and the deposition of Ir nanoparticles. The anodization time was varied to grow three different types of nanotubular structures exhibiting different lengths and wall thicknesses and thus a variety of properties. A comparison of milled samples with different degrees of nanotubular clustering and morphology retention, but with identical chemical compositions and Ir nanoparticle size distributions and dispersions, revealed that the nanotubular support morphology is the determining factor governing the catalyst’s OER activity and stability. Our study is supported by various state-of-the-art materials’ characterization techniques, like X-ray photoelectron spectroscopy, scanning and transmission electron microscopies, Xray powder diffraction and absorption spectroscopy, and electrochemical cyclic voltammetry. Anodic oxidation proved to be a very suitable way to produce high-surface-area powder-type catalysts as the produced material greatly outperformed the IrO2 benchmarks as well as the Ir-supported samples on morphologically different TiONx from previous studies. The highest activity was achieved for the sample prepared with 3 h of anodization, which had the most appropriate morphology for the effective removal of oxygen bubbles.
Najdeno v: ključnih besedah
Ključne besede: electrocatalysis, oxygen-evolution reaction, TiONx-Ir powder catalyst, iridium nanoparticles, anodic oxidation, morphology−activity correlation
Objavljeno: 04.01.2021; Ogledov: 43; Prenosov: 0
.pdf Polno besedilo (6,36 MB)

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