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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, final research report

Found in: ključnih besedah
Summary of found: ...fuel cell, ethanol oxidation, graphene, oxygen reduction, catalyst, pt-free, electrochemical impedance spectroscopy...
Keywords: fuel cell, ethanol oxidation, graphene, oxygen reduction, catalyst, pt-free, electrochemical impedance spectroscopy
Published: 03.12.2020; Views: 371; Downloads: 0
.pdf Fulltext (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, 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: 2804; 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: 2727; Downloads: 0
.pdf Fulltext (2,02 MB)

Blaž Winkler, 2019, 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: 1503; Downloads: 88
.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: 990; Downloads: 0
.pdf Fulltext (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, original scientific article

Abstract: 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.
Found in: ključnih besedah
Keywords: electrocatalysis, oxygen-evolution reaction, TiONx-Ir powder catalyst, iridium nanoparticles, anodic oxidation, morphology−activity correlation
Published: 04.01.2021; Views: 298; Downloads: 0
.pdf Fulltext (6,36 MB)

Secondary organic aerosol formation from semi- and intermediate-volatility organic compounds and glyoxal
Jose L. Jimenez, Sasha Madronich, Rainer Volkamer, Eleanor M. Waxman, Katja Džepina, Barbara Ervens, Julia Lee-Taylor, Bernard Aumont, 2013, original scientific article

Abstract: The role of aqueous multiphase chemistry in the formation of secondary organic aerosol (SOA) remains difficult to quantify. We investigate it here by testing the rapid formation of moderate oxygen-to-carbon (O/C) SOA during a case study in Mexico City. A novel laboratory-based glyoxal-SOA mechanism is applied to the field data, and explains why less gas-phase glyoxal mass is observed than predicted. Furthermore, we compare an explicit gas-phase chemical mechanism for SOA formation from semi- and intermediate-volatility organic compounds (S/IVOCs) with empirical parameterizations of S/IVOC aging. The mechanism representing our current understanding of chemical kinetics of S/IVOC oxidation combined with traditional SOA sources and mixing of background SOA underestimates the observed O/C by a factor of two at noon. Inclusion of glyoxal-SOA with O/C of 1.5 brings O/C predictions within measurement uncertainty, suggesting that field observations can be reconciled on reasonable time scales using laboratory-based empirical relationships for aqueous chemistry.
Found in: ključnih besedah
Summary of found: testing the rapid formation of moderate oxygen-to-carbon (O/C) SOA during a case study in...
Keywords: secondary organic aerosol, glyoxal, aqueous multiphase chemistry, oxygen-to-carbon ratio, single scattering albedo
Published: 11.04.2021; Views: 59; Downloads: 0
.pdf Fulltext (724,40 KB)

Paramagnetic intrinsic point defects in alkali phosphate glasses
Nadege Ollier, Luigi Giacomazzi, Nikita S. Shcheblanov, Nicolas Richard, Mikhail E. Povarnitsyn, Shinji Kohara, Matjaž Valant, Layla Martin-Samos, 2021, original scientific article

Found in: ključnih besedah
Summary of found: ... oxygen, electron paramagnetic resonance spectroscopy, phosphates, amorphous materials,...
Keywords: oxygen, electron paramagnetic resonance spectroscopy, phosphates, amorphous materials, defects
Published: 04.05.2021; Views: 29; Downloads: 0
.pdf Fulltext (2,23 MB)

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