1. Light-Assisted Catalysis and the Dynamic Nature of Surface Species in the Reverse Water Gas Shift Reaction over Cu/γ-Al2O3Kristijan Lorber, Iztok Arčon, Matej Huš, Janez Zavašnik, Jordi Sancho-Parramon, Anže Prašnikar, Blaž Likozar, Nataša Novak Tušar, Petar Djinović, izvirni znanstveni članek Opis: The reverse water gas shift (RWGS) reaction converts CO2 and H2 into CO and water. We investigated Cu/γ-Al2O3 catalysts in both thermally driven and light-assisted RWGS reactions using visible light. When driven by combined visible light and thermal energy, the CO2 conversion rates were lower than in the dark. Light-assisted reactions showed an increase in the apparent activation energy from 68 to 87 kJ/mol, indicating that light disrupts the energetically favorable pathway active in the dark. A linear correlation between irradiance and decreasing reaction rate suggests a photon-driven phenomenon. In situ diffuse reflectance infrared Fourier transform spectroscopy and TD-DFT analyses revealed that catalyst illumination causes significant, partly irreversible surface dehydroxylation, highlighting the importance of OH groups in the most favorable RWGS pathway. This study offers a novel approach to manipulate surface species and control activity in the RWGS reaction.
Ključne besede: light-assisted catalysis, reaction mechanism, in situ spectroscopy, hydroxyl, copper, RWGS
Objavljeno v RUNG: 07.01.2025; Ogledov: 502; Prenosov: 6
 Celotno besedilo (5,73 MB)
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2. Computational study of the HLTF ATPase remodeling domain suggests its activity on dsDNA and implications in damage toleranceMartin Ljubič, Claudia D'Ercole, Yossma Waheed, Ario De Marco, Jure Borišek, Matteo De March, 2024, izvirni znanstveni članek Ključne besede: DNA repairing mechanism, protein modeling, chromatin remodeler, helicase-like transcription factor
Objavljeno v RUNG: 15.11.2024; Ogledov: 865; Prenosov: 2
Celotno besedilo (5,17 MB) |
3. Initial oxidation of low index Mg surfaces investigated by SCLS and DFTZhe Xing, Mattia Fanetti, Sandra Gardonio, Elsebeth Schröder, Dmytro Orlov, 2024, izvirni znanstveni članek Ključne besede: oxidation mechanism, surface core level shift, density functional theory, surface reconstruction, magnesium oxidation
Objavljeno v RUNG: 25.07.2024; Ogledov: 1457; Prenosov: 6
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4. THERMAL AND COMBINED PHOTO-THERMAL DRY REFORMING OF METHANE (DRM) OVER NANOSHAPED Ni/CeO2 CATALYSTS : DISSERTATIONKristijan Lorber, 2023, doktorska disertacija Opis: Dry reforming of methane (DRM) is an attractive reaction for converting the two major greenhouse gases CH4 and CO2 into the product syngas. H2 and CO as synthesis gas are important chemical feedstocks for the further production of valuable products as well as for the production of long-chain hydrocarbons by the Fisher-Tropsch process. High operating temperatures due to the endothermic nature of the DRM process and the occurrence of several side reactions such as Reverse Water Gas Shift, Methane Cracking and Boudoard reaction make the DRM process unattractive for industrial application.
For the catalytic application of DRM in thermal mode (thermal energy drives the reaction), different CeO2 morphologies, namely nanorods, nanocubes, and nanospheres, were synthesized by a hydrothermal method. The best catalyst for DRM was found to be 2 wt. % Ni loaded in CeO2 rods morphology (2Ni-R). Characterization techniques (XRD, N2-physisorption, TEM, in-situ XANES/EXAFS TPR and CO2 TPD) were used to investigate the structural and redox properties of the catalysts. The mechanism of CO2 activation on reduced Ni/CeO2-x during DRM was proposed using DFT calculations and in-situ DRIFTS measurements combined with mass spectrometry.
The 2Ni-R catalyst, which performed best in thermal DRM reaction, was studied under photo-thermal conditions where it was stimulated by both visible light and thermal energy. The catalytic activity was observed even at low (140 °C) temperatures, and the obtained CH4 and CO2 conversion, as well as H2/CO ratio exceeded thermodynamic limitations. XRD, TEM, and H2-physisorption techniques were used for structural characterization, while in-situ UV-Vis measurements were performed to study the optical properties of the catalyst. By using suitable long-pass filters and with the help of theoretical calculations, we were able to distinguish two photo mechanisms which contribute to photocatalytic activity under photo-thermal mode of the DRM reaction. Shorter wavelengths (< 450 nm) supported the charge transfer and generation mechanism in reduced CeO2-x, while longer wavelengths (> 450 nm) promoted near-field enhancement. However, under full spectrum of visible light (400 - 800 nm), the charge transfer and generation mechanism was dominant and led to 2-3 times higher CH4 activation rates compared to near-field enhancement.
Ključne besede: DRM, CeO2 nanoshapes, reaction mechanism, photocatalysis
Objavljeno v RUNG: 22.09.2023; Ogledov: 2486; Prenosov: 56
Celotno besedilo (6,64 MB) |
5. Antibiotics and their different application strategies in controlling the biofilm forming pathogenic bacteriaFazlurrahman Khan, Dung T N Pham, Sandra Oloketuyi, Young-Mog Kim, 2020, pregledni znanstveni članek Opis: Background: The establishment of a biofilm by most pathogenic bacteria has been known as one of the resistance mechanisms against antibiotics. A biofilm is a structural component where the bacterial community adheres to the biotic or abiotic surfaces by the help of Extracellular Polymeric Substances (EPS) produced by bacterial cells. The biofilm matrix possesses the ability to resist several adverse environmental factors, including the effect of antibiotics. Therefore, the resistance of bacterial biofilm-forming cells could be increased up to 1000 times than the planktonic cells, hence requiring a significantly high concentration of antibiotics for treatment.
Methods: Up to the present, several methodologies employing antibiotics as an anti-biofilm, antivirulence or quorum quenching agent have been developed for biofilm inhibition and eradication of a pre-formed mature biofilm.
Results: Among the anti-biofilm strategies being tested, the sub-minimal inhibitory concentration of several antibiotics either alone or in combination has been shown to inhibit biofilm formation and down-regulate the production of virulence factors. The combinatorial strategies include (1) combination of multiple antibiotics, (2) combination of antibiotics with non-antibiotic agents and (3) loading of antibiotics onto a carrier.
Conclusion: The present review paper describes the role of several antibiotics as biofilm inhibitors and also the alternative strategies adopted for applications in eradicating and inhibiting the formation of biofilm by pathogenic bacteria.
Ključne besede: Antibiotics, biofilm inhibition, multiple antibiotics, pathogenic bacteria, resistance mechanism, virulence factors
Objavljeno v RUNG: 14.01.2021; Ogledov: 3889; Prenosov: 0
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6. Effect of Na, Cs and Ca on propylene epoxidation selectivity over CuOx/SiO2 catalysts studied by catalytic tests, in-situ XAS and DFTJanvit Teržan, Matej Huš, Iztok Arčon, Blaž Likozar, Petar Djinović, 2020, izvirni znanstveni članek Opis: This research focuses on epoxidation of propylene over pristine, Na, Ca and Cs modified
CuOx/SiO2 catalysts using O2. The selectivity of the reaction is analyzed using a combination
of catalytic tests, in-situ XAS and DFT calculations. The initially present subnanometer CuO
clusters are present in all catalysts which re-disperse/flatten during reaction. During catalytic
reaction, the Cu1+ becomes the predominant oxidation state. There is no correlation between
propylene oxide (PO) selectivity and copper oxidation state. DFT analysis of the propylene
reaction pathway revealed that Na, Cs, and Ca addition decreases the bonding strength of
propylene to CuO and decreases the O2 activation barrier, while simultaneously increase the
exothermicity of O2 dissociation. The Na induced Cu-O bond modification decreases the
activation barrier from 0.87 to 0.71 eV for the oxametallacycle (OMC) ring closure (first step
in the reaction pathway favoring selectivity towards PO) compared to pristine 5Cu catalyst.
At the same time, we observed an increase (from 0.45 to 0.72 eV) of the barrier for the
abstraction of allylic hydrogen. The opposite effect is achieved by Ca addition: the activation
barrier for OMC ring closure increases to 1.08 eV and that for allylic hydrogen stripping
decreases to 0.16 eV.
Ključne besede: Alkali modification, propylene epoxidation, reaction mechanism, copper oxide, activation barrier.
Objavljeno v RUNG: 05.06.2020; Ogledov: 4080; Prenosov: 0
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7. Synthesis of a Cu/ZnO Nanocomposite by Electroless Plating for the Catalytic Conversion of CO2 to MethanolMaja Pori, Iztok Arčon, Damjan Lašič Jurković, Marjan Marinšek, Goran Dražić, Blaž Likozar, Zorica Crnjak Orel, 2019, izvirni znanstveni članek Opis: The process of methanol synthesis based on the hydrogenation of CO2
was investigated over binary Cu/ZnO catalyst materials,
prepared by applying a novel electroless plating fabrication method. The activity of the produced catalytic samples
was determined at temperature range between 200 and 300 °C and the feedstock conversion data were supplemented with
a detailed microstructure analysis using high-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction
(XRD) and Cu and Zn K-edge, X-ray absorption near-edge structure (XANES) measurements and extended X-ray
absorption fine-structure (EXAFS) measurements. It was confirmed that the disorder in the Cu crystallites created unique
geometrical situations, which acted as the additional reactive centres for the adsorption of the reactant molecule species.
Copper and zinc structural synergy (spill-over) was also demonstrated as being crucial for the carbon dioxide’s activation.
EXAFS and XANES results provide strong evidence for surface alloying between copper and zinc and thus the present results
demonstrate new approach applicable for explaining metal–support interactions.
Ključne besede: EXAFS, CuZn alloy, Spillover mechanism, CO2 valorization, Electroless deposition method, Heterogeneous
catalysis
Objavljeno v RUNG: 12.04.2019; Ogledov: 4972; Prenosov: 0
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