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11.
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.
Ključne besede: electrocatalysis, oxygen-evolution reaction, TiONx-Ir powder catalyst, iridium nanoparticles, anodic oxidation, morphology−activity correlation
Objavljeno v RUNG: 04.01.2021; Ogledov: 2485; Prenosov: 0
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Airborne Microalgae: Insights, Opportunities, and Challenges
Sylvie V. M. Tesson, Carsten Ambelas Skjøth, Tina Šantl Temkiv, Jakob Löndahl, 2016, pregledni znanstveni članek

Ključne besede: Airborne microalgae, health effects, ice-nucleation activity, microalgae dispersal
Objavljeno v RUNG: 04.01.2021; Ogledov: 2218; Prenosov: 0
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The multi-purpose role of hairiness in the lichens of coastal environments: Insights from Seirophora villosa (Ach.) Frödén
Elisabetta Bianchi, Renato Benesperi, Ilaria Colzi, Andrea Coppi, Lorenzo Lazzaro, Luca Paoli, Alessio Papini, Sara Pignattelli, Corrado Tani, Pamela Vignolini, Cristina Gonnelli, 2019, izvirni znanstveni članek

Opis: The fruticose epiphytic lichen Seirophora villosa, strictly associated with Juniperus shrublands in the Mediterranean basin, was used to investigate the role of hairiness on a lichen thallus, as a characteristic morphological trait. We evaluated the effect of hair removal on the physiological parameters of a set of samples, during desiccation and on exposure to different salt concentrations. Hairy thalli were less affected by salt, suggesting that during dehydration, the presence of hair protects the thallus from light irradiance, oxidative stresses and the lipid peroxidation generated by free radicals, and could offer passive, but selective, water control. Our results showed that hair could not only increase thallus surface and promote water absorption when availability is low, but could also repel the salt dissolved in water by activating a passive resistance mechanism, by preventing salt entering.
Ključne besede: Antioxidant activity Chlorophyll a fluorescence Juniperus shrublands Hair MDA Salt stress
Objavljeno v RUNG: 20.04.2020; Ogledov: 2662; Prenosov: 0
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Improved photocatalytic activity of anatase-rutile nanocomposites induced by low-temperature sol-gel Sn-modification of TiO2
Ksenija Maver, Iztok Arčon, Urška Lavrenčič Štangar, Mattia Fanetti, Saim Emin, Matjaž Valant, 2020, izvirni znanstveni članek

Opis: The Sn-modified TiO2 photocatalysts are prepared by low-temperature sol-gel processing based on organic titanium and tin precursors with varied Sn concentrations (from 0.1–20 mol .%). The role of Sn dopant as the promotor of the formation of TiO2 rutile crystalline phase is explained and the optimal Sn concentration for preparation of efficient Sn-modified titania photocatalyst is determined. Up to 40 % increase in photocatalytic activity is achieved in Sn-modified TiO2 photocatalytic thin films dried at 150 °C with low Sn concentrations in the range from 0.1 to 1 mol .%. At low Sn concentrations optimal ratio between anatase and rutile (nano)crystals is obtained, which facilitates charge separation at the TiO2 photocatalyst’s surface. When the concentration of Sn increases above 5 mol.% or when the films are calcined at 500 °C, the relative amount of rutile phase with inferior photocatalytic activity, increases and the nanocrystals of titania grow, leading to fewer active sites per unit mass and the reduction of activity in comparison to unmodified TiO2.
Ključne besede: Anatase-rutile Sn-modified TiO2 XAS analysis Photocatalytic activity
Objavljeno v RUNG: 10.02.2020; Ogledov: 2949; Prenosov: 0
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