1. Disinfection of wastewater using porous Fe2O3 thin film : master's thesisRanin M. D. Ismail, 2024, master's thesis Abstract: The contamination of water bodies by microorganisms is seen as a highly significant issue that poses a threat to human and animal well-being. The primary objective of this master thesis is to develop and evaluate an environmentally friendly photoelectrochemical (PEC) method using porous Fe₂O₃ thin films for the disinfection of wastewater. This thesis presents the novel application of porous Fe₂O₃ thin films, which were produced using a cost-effective spin-coating technique, to improve the process of PEC disinfection. The PEC approach has been demonstrated to be highly effective in disinfection of wastewaters deliberately contaminated with E. coli bacteria. The crystallinity of the Fe₂O₃ porous thin films was confirmed using X-ray diffraction (XRD), while the film morphology was studied using scanning electron microscopy (SEM). The PEC disinfection procedures were conducted in the presence of two separate electrolytes, sodium sulfite (Na₂SO₃) and sodium chloride (NaCl), which were chosen for their specific roles in improving the effectiveness of disinfection. The PEC method shown efficacy in inactivating E. coli, with 45% of the bacteria being inactivated in the presence of 2 mM Na₂SO₃ and complete inactivation achieved with 20 mM NaCl. The findings suggest that the PEC disinfection process is a highly efficient and eco-friendly technology that can be used as a practical substitute for traditional disinfection methods. As a result, it has potential applications in ensuring public safety and safeguarding the environment, particularly in relation to wastewater treatment. Keywords: Treated wastewater, Disinfection, Escherichia coli, Photoelectrochemical oxidation, Fe2O3 thin films, Sodium sulfite and Sodium chloride. Published in RUNG: 09.09.2024; Views: 811; Downloads: 13 Full text (2,23 MB) |
2. Initial oxidation of low index Mg surfaces investigated by SCLS and DFTZhe Xing, Mattia Fanetti, Sandra Gardonio, Elsebeth Schröder, Dmytro Orlov, 2024, original scientific article Keywords: oxidation mechanism, surface core level shift, density functional theory, surface reconstruction, magnesium oxidation Published in RUNG: 25.07.2024; Views: 992; Downloads: 5 Full text (7,92 MB) |
3. Winning combination of Cu and Fe oxide clusters with an alumina support for low-temperature catalytic oxidation of volatile organic compoundsTadej Žumbar, Iztok Arčon, Petar Djinović, Giuliana Aquilanti, Gregor Žerjav, Albin Pintar, Alenka Ristić, Goran Dražić, Janez Volavšek, Gregor Mali, Margarita Popova, Nataša Zabukovec Logar, Nataša Novak Tušar, 2023, original scientific article Abstract: A γ-alumina support functionalized with transition metals is one of the most widely used industrial catalysts for the total oxidation of volatile organic compounds (VOCs) as air pollutants at higher temperatures (280−450 °C). By rational design of a
bimetal CuFe-γ-alumina catalyst, synthesized from a dawsonite alumina precursor, the activity in total oxidation of toluene as a model VOC at a lower temperature (200−380
°C) is achieved. A fundamental understanding of the catalyst and the reaction mechanism is elucidated by advanced microscopic and spectroscopic characterizations as well as by temperature-programmed surface techniques. The nature of the metal−support bonding and the optimal abundance between Cu−O−Al and Fe−O−Al species in the catalysts leads to synergistic catalytic activity promoted by small amounts of iron (Fe/Al = 0.005).
The change in the metal oxide−cluster alumina interface is related to the nature of the
surfaces to which the Cu atoms attach. In the most active catalyst, the CuO6 octahedra are
attached to 4 Al atoms, while in the less active catalyst, they are attached to only 3 Al atoms. The oxidation of toluene occurs via the Langmuir−Hinshelwood mechanism. The presented material introduces a prospective family of low-cost and scalable oxidation catalysts with superior efficiency at lower temperatures. Keywords: Iron oxide clusters, copper oxide clusters, alumina support, synergistic effect, low-temperature total catalytic oxidation, toluene, Cu, Fe XANES, EXAFS Published in RUNG: 06.07.2023; Views: 2730; Downloads: 27 Full text (11,05 MB) This document has many files! More... |
4. Stable seawater oxidation with a self-healing oxygen-evolving catalystXiaojian Zhang, Chao Feng, Zeyu Fan, Beibei Zhang, Yequan Xiao, Andraž Mavrič, Nadiia Pastukhova, Matjaž Valant, Yi-Fan Han, Yanbo Li, 2023, original scientific article Abstract: Direct seawater electrolysis is key to massive hydrogen fuel production without the depletion of precious freshwater resources and the need for high-purity electrolytes. However, the presence of high-concentration chloride ions (Cl−) and alkaline-earth metal ions (Mg2+, Ca2+) poses great challenges to the stability and selectivity of the catalysts for seawater splitting. Here, we demonstrate a self-healing oxygen evolution reaction (OER) catalyst for long-term seawater electrolysis. By suppressing the competitive chlorine evolution reaction and precipitating the alkaline-earth metal ions through an alkaline treatment of the seawater, stable seawater oxidation is achieved owing to the self-healing ability of the borate-intercalated nickel–cobalt–iron oxyhydroxides (NiCoFe-Bi) OER catalyst under highly-alkaline conditions. The self-healing NiCoFe-Bi catalyst achieves stable seawater oxidation at a large current density of 500 mA cm−2 for 1000 h with near unity Faraday efficiency. Our results have demonstrated strong durability and high OER selectivity of the self-healing catalyst under harsh conditions, paving the way for industrial large-scale seawater electrolysis. Keywords: chemistry, electrocatalysis, seawater oxidation, oxygen evolution reaction Published in RUNG: 08.05.2023; Views: 2012; Downloads: 5 Link to file This document has many files! More... |
5. Non-covalent ligand-oxide interaction promotes oxygen evolutionQianbao Wu, Junwu Liang, Mengjun Xiao, Chang Long, Lei Li, Zhenhua Zeng, Andraž Mavrič, Xia Zheng, Jing Zhu, Matjaž Valant, 2023, original scientific article Abstract: Strategies to generate high-valence metal species capable of oxidizing water often employ composition and coordination tuning of oxide-based catalysts, where strong covalent interactions with metal sites are crucial. However, it remains unexplored whether a relatively weak “non-bonding” interaction between ligands and oxides can mediate the electronic states of metal sites in oxides. Here we present an unusual non-covalent phenanthroline-CoO2 interaction that substantially elevates the population of Co4+ sites for improved water oxidation. We find that phenanthroline only coordinates with Co2+ forming soluble Co(phenanthroline)2(OH)2 complex in alkaline electrolytes, which can be deposited as amorphous CoOxHy film containing non-bonding phenanthroline upon oxidation of Co2+ to Co3+/4+. This in situ deposited catalyst demonstrates a low overpotential of 216 mV at 10 mA cm−2 and sustainable activity over 1600 h with Faradaic efficiency above 97%. Density functional theory calculations reveal that the presence of phenanthroline can stabilize CoO2 through the non-covalent interaction and generate polaron-like electronic states at the Co-Co center. Keywords: water oxidation, cobalt hydroxide, ligand-metal interactions Published in RUNG: 23.02.2023; Views: 2674; Downloads: 19 Full text (1,77 MB) |
6. Removal of copper from aqueous solutions with zeolites and possible treatment of exhaust materialsNataša Zabukovec Logar, Iztok Arčon, Janez Kovač, Margarita Popova, 2021, original scientific article Abstract: The mechanism of Cu2+ loading into commercially available natural HEU-type and synthetic LTA-type zeolites for their
possible use in environmental processes, such as water and air treatment applications, was studied. Elemental analysis,
SEM/EDXS, XRD, XAS and XPS analyses revealed 4-fold coordination of Cu2+ cations with oxygen atoms in the pores, a
predominant location of copper atoms on the surface of crystallites and retained crystallinity of zeolites throughout the
processes. The post-treatment of Cu2+-loaded samples with HCl and/or NaCl solutions confirmed the predominantly
reversible sorption of copper on zeolites from aqueous solutions by ion-exchange mechanism and, therefore, excellent
regeneration possibilities for both types of zeolites. Furthermore, with the calcination of exhaust metal-loaded zeolites,
catalysts for total toluene oxidation reaction, as a model VOC pollutant, were obtained. Keywords: Cu2+ ion exchange, Total toluene oxidation, X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, Zeolite Published in RUNG: 03.06.2021; Views: 2712; Downloads: 154 Link to full text This document has many files! More... |
7. Effect of the Morphology of the High-Surface-Area Support on the Performance of the Oxygen-Evolution Reaction for Iridium NanoparticlesLeonard 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. Keywords: electrocatalysis, oxygen-evolution reaction, TiONx-Ir powder catalyst, iridium nanoparticles, anodic oxidation, morphology−activity correlation Published in RUNG: 04.01.2021; Views: 3423; Downloads: 0 This document has many files! More... |
8. Designing new renewable nano-structured electrode and membrane materials for direct alkaline ethanol fuel cell : Information on catalytic activity, structure and electric current con- ductivity of new catalysts on supporting substratesEgon Pavlica, Gvido Bratina, Jørgen Svendby, Qingjun Chen, Jia Yang, De Chen, Ji-Song Huang, Jessie Lue Shingjiang, 2020, final research report Keywords: fuel cell, ethanol oxidation, graphene, oxygen reduction, catalyst, pt-free, electrochemical impedance spectroscopy Published in RUNG: 03.12.2020; Views: 3854; Downloads: 0 This document has many files! More... |
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10. Atomic-level mechanisms of magnesium oxidationSandra Gardonio, Mattia Fanetti, Matjaž Valant, Dmytro Orlov, 2016, published scientific conference contribution Abstract: Magnesium has been recently becoming an increasingly popular material for various applications. However, excessive chemical reactivity, and oxidation rate in particular, is a major obstruction on the way of Mg to become widely adopted. A significant problem causing the lack of Mg reactivity control is insufficient understanding of mechanisms involved in the oxidation of magnesium surface. Herewith we present the investigation of atomic-level mechanisms of oxidation initiation and propagation in pure Mg. Namely, X-ray photoelectron spectroscopy at synchrotron Elettra was used as a surface sensitive direct method to determine the valence of Mg and O and the valence band states at the early stage of oxide formation over a principal, most densely packed, crystallographic plane (0001) in pure Mg. The mechanisms of oxygen adsorption on magnesium free surface followed by oxidation (i.e. initiation and kinetics of MgO formation) are clarified. Copyright © 2016 by The Minerals, Metals & Materials Society. All rights reserved. Keywords: Magnesium, Oxidation, Synchrotron radiation, X-ray photoelectron spectroscopy Published in RUNG: 25.08.2017; Views: 5885; Downloads: 0 This document has many files! More... |