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Supported nanostructured Pd catalyst using atomic layer deposition: from methanol oxidation to hydrogen evolution reaction
Bawab, Bilal ; Knez, Mato (oponent) ; Nielsch, Kornelius (oponent) ; Macák, Jan (vedoucí práce)
In this thesis, the catalytic capabilities of Pd species deposited by Atomic Layer Deposition (ALD) was explored on different substrates. Pd species composed of Nanoparticles (NPs) and Single atoms (SAs) were synthesized on anodic TiO2 nanotube (TNT) layers and carbon papers, respectively, to investigate their performance in methanol electro-oxidation and the alkaline hydrogen evolution reaction (HER). Pd NPs were deposited on TNT layers as methanol oxidation catalyst, leveraging their large surface area and direct electrical contact through the titanium foil. TEM analysis showed Pd particle sizes between 7 and 12 nm, with a shift to a porous Pd layer formation beyond 450 ALD cycles. Cyclic voltammetry revealed that catalytic activity peaked at 400 and 450 cycles, indicating optimal Pd loading and anti-poisoning characteristics, potentially enabling direct CH3OH to CO2 conversion. The other role the Pd achieved through the presence of SAs and NPs. Pd species were decorated on carbon papers were studied as HER catalyst. the samples before and after electrochemical measurements were characterized with X-ray photoelectron spectroscopy confirming the presence of Pd2+ species. The electrochemical active surface area increased significantly with ALD cycles, reaching a plateau at 300c Pd. Notably, CP 600c Pd demonstrated an overpotential of 4.55 mV, the lowest reported for Pd electrocatalysts in alkaline conditions. This highlights the synergistic effects of Pd configurations on HER enhancement and explores the mechanism by which the HER process occurs.
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Alternative approaches for Preparation of AlN Nanolayers by Atomic Layer Deposition
Dallaev, Rashid ; Krčma, František (oponent) ; Kolařík, Vladimír (oponent) ; Sedlák, Petr (vedoucí práce)
Aluminum nitride (AlN) is a promising semi-conductive material with a wide band gap. Thin films of AlN find implementation in a variety of electronic and optoelectronic devices. First and foremost, the aim of the research presented within the scope of this dissertation is to introduce new precursors into ALD process for deposition of AlN thin films. The proposed precursors are superior to traditional ones either in cost-efficiency or reactivity. A part of the dissertation is devoted to enhancement of the understanding of chemical processes which take place during and after deposition. In this regard, a working solution to improving the chemical composition of the resulting films, as well as ameliorating deficiencies, for instance, oxidization, has been proposed. Another important aspect of this study has to do with a thorough analysis of hydrogen phenomenon in AlN ALD thin films. Hydrogen impurities have been investigated with the use of accurate and advanced techniques belonging to ion-beam analysis (IBA) groups.
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Alternative approaches for Preparation of AlN Nanolayers by Atomic Layer Deposition
Dallaev, Rashid ; Krčma, František (oponent) ; Kolařík, Vladimír (oponent) ; Sedlák, Petr (vedoucí práce)
Aluminum nitride (AlN) is a promising semi-conductive material with a wide band gap. Thin films of AlN find implementation in a variety of electronic and optoelectronic devices. First and foremost, the aim of the research presented within the scope of this dissertation is to introduce new precursors into ALD process for deposition of AlN thin films. The proposed precursors are superior to traditional ones either in cost-efficiency or reactivity. A part of the dissertation is devoted to enhancement of the understanding of chemical processes which take place during and after deposition. In this regard, a working solution to improving the chemical composition of the resulting films, as well as ameliorating deficiencies, for instance, oxidization, has been proposed. Another important aspect of this study has to do with a thorough analysis of hydrogen phenomenon in AlN ALD thin films. Hydrogen impurities have been investigated with the use of accurate and advanced techniques belonging to ion-beam analysis (IBA) groups.
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