National Repository of Grey Literature 35 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Study of the effect of thin film catalyst morphology on efficiency of water electrolyzer with proton conducting membrane
Hrbek, Tomáš ; Matolín, Vladimír (advisor) ; Nováková, Jaroslava (referee)
Title: Study of the effect of thin film catalyst morphology on efficiency of water electrolyzer with proton conducting membrane Author: Tomáš Hrbek Department: Department of Surface and Plasma Science Supervisor: prof. RNDr. Vladimír Matolín, DrSc., Department of Surface and Plasma Science Abstract: This bachelor thesis deals with the possibility of reducing the amount of noble metals in catalytic layers of proton exchange water electrolyzer (PEM-WE). The PEM-WE is an important unit of hydrogen economy as it allows storage of excess energy from renewable sources in the form of chemical energy. In the first part, etched membrane electrolyzers were prepared and tested, membrane etching is a previously unpublished procedure leading to a reduction of the amount of catalyst. Etched membranes were studied by scanning electron microscopy and, consequently tested in real working conditions in electrolyzers. In the second part of the work; Ir and IrO2 were compared as catalysts for PEM-WE anode. Their in-cell performance was tested directly in the electrolysers and in controlled condition by rotating disk electrode. Keywords: electrolyzer, magnetron sputtering, thin-layer catalyst, etched mem- brane PEM, Ir vs. IrO2
Study of CO and N2 Interaction with Anode Catalysts of Proton-Exchange Membrane Fuel Cells
Fusek, Lukáš ; Matolín, Vladimír (advisor) ; Mysliveček, Josef (referee)
Poisoning of the catalyst seems to be one of the most serious problems preventing a widespread commercialization of fuel cell technology. This thesis focuses on the effect of CO poisoning and hydrogen dilution by nitrogen on performance of fuel cells with low platinum content. Catalysts were deposited by magnetron sputtering directly on membrane etched by plasma. Alloys with different platinum-ruthenium ratio were used to mitigate the CO poisoning. We found that presence of nitrogen has almost negligible effect on the fuel cell performance. On the other hand, CO, even in small concentrations, caused a significant drop in power density. PtRu with atomic ratio 2:1 and 1:1 showed the best CO tolerance.
Thin-film catalysts for proton exchange membrane water electrolyzers and unitized regenerative fuel cells
Kúš, Peter ; Matolín, Vladimír (advisor)
This dissertation thesis revolves around hydrogen economy and energy-storage electrochemical systems. More specifically, it investigates the possibility of using magnetron sputtering for deposition of efficient thin-film anode catalysts with low noble metal content for proton exchange membrane water electrolyzers (PEM-WEs) and unitized regenerative fuel cells (PEM-URFCs). The motivation for this research derives from the urgent need of minimizing the price of mentioned electrochemical devices should they enter mass production. Numerous experiments were carried out, correlating the actual in-cell performance with the varying position of thin-film catalyst within the membrane electrode assembly, with the composition of high-surface support sublayer and with the chemical structure of the catalyst itself. The wide arsenal of analytical methods ranging from electrochemical impedance spectroscopy through scanning electron microscopy to photoelectron spectroscopy allowed us to describe complex phenomena behind different obtained efficiencies. Consequent systematic optimizations led to the design of novel PEM-WE anode thin-film iridium catalyst with thickness of just 50 nm, supported on optimized TiC-based sublayer which performed similarly to standard counterparts despite using just a fraction of their noble metal...
Thin-film catalysts for proton exchange membrane water electrolyzers and unitized regenerative fuel cells
Kúš, Peter ; Matolín, Vladimír (advisor) ; Napporn, Teko Wilhelmin (referee) ; Plecenik, Tomáš (referee)
This dissertation thesis revolves around hydrogen economy and energy-storage electrochemical systems. More specifically, it investigates the possibility of using magnetron sputtering for deposition of efficient thin-film anode catalysts with low noble metal content for proton exchange membrane water electrolyzers (PEM-WEs) and unitized regenerative fuel cells (PEM-URFCs). The motivation for this research derives from the urgent need of minimizing the price of mentioned electrochemical devices should they enter mass production. Numerous experiments were carried out, correlating the actual in-cell performance with the varying position of thin-film catalyst within the membrane electrode assembly, with the composition of high-surface support sublayer and with the chemical structure of the catalyst itself. The wide arsenal of analytical methods ranging from electrochemical impedance spectroscopy through scanning electron microscopy to photoelectron spectroscopy allowed us to describe complex phenomena behind different obtained efficiencies. Consequent systematic optimizations led to the design of novel PEM-WE anode thin-film iridium catalyst with thickness of just 50 nm, supported on optimized TiC-based sublayer which performed similarly to standard counterparts despite using just a fraction of their noble metal...
Investigation of new catalysts for polymer membrane fuel cells
Fiala, Roman ; Matolín, Vladimír (advisor) ; Bystroň, Tomáš (referee) ; Napporn, Teko Wilhelmin (referee)
Fuel cells are a promising alternate power source of electricity. Despite of sig- nificant improvement that was reached by research throughout recent decades, the technology is not still ready to large scale commercial use. The catalyst of fuel cell (FC) should be still investigated due to fact that the only reliable functional catalyst is Platinum, a noble and expensive metal, which makes the use of this technology not competitive. In this thesis, investigation of Platinum doped ceria catalyst and its modification prepared by physical technique of deposition which is magnetron sputtering is presented. The catalyst was studied using standard sur- face analytic techniques (PES, SEM, AFM, XANES) as well as electrochemical measurement (CV, PEIS). The principal part of this thesis reports direct analyses of catalyst in fuel cell using an individually designed fuel cell test station. Con- sidering the high power density (PD) about 1 W cm−2 and substantially higher specific power per gram of Platinum (SP) 1.6 kW mg−1 in comparison with com- mercial Pt-Ru/Pt-C reference catalyst and additionally the relatively longtime stability, the sputtered Platinum doped cerium oxide based catalyst was found a suitable catalyst for PEM FC. Moreover, possible substitution of Pt and CeO2 by other elements was shown. Beside of...
Study of thin film catalysts for oxygen reduction reaction on proton exchange membrane fule cell cathode
Komárková, Zuzana ; Matolín, Vladimír (advisor) ; Václavů, Michal (referee)
In this thesis, we present the investigation of influence of methanol crossover, which significantly decreases the performance of DMFC (Direct Methanol Fuel Cell). Additionally the poisoning effect occurs on the cathode side. The durability of cathode catalyst exposed by methanol vapor is studied. Moreover, the regene- rative behavior after exposition has been found. The comparison of commercial catalyst with our own sputtered Pt and PtCo and PtRu thin layers as cata- lyst is presented. Obtained results have shown that PtCo is reasonable compro- mise between pure Pt, which has high performance, and PtRu, which is tolerant to methanol poisoning. Future research should further evaluate the advantages of PtCo cathode catalyst prepared by standard procedures and its market poten- tial in comparison with PtRu. 1
Study of thin film catalysts for direct methanol fuel cell anode
Fusek, Lukáš ; Matolín, Vladimír (advisor) ; Nováková, Jaroslava (referee)
This thesis is focused on the study of catalyst layers for direct methanol fuel cell anode prepared by a new method using magnetron sputtering. Homemade as well as commercial supports were used. The study of properties of prepared layers was carried out in fuel cell using methods of electrochemical analysis, such as electrochemical impedance spectroscopy and cyclic voltametry for examination of conductivity, catalyst activity and resistance to poisoning by residual carbon species. Polarization curves were used to investigate power and diffusion properties. A reference cell composed of commercially-available electrodes was chosen for comparison.
Low Platinum Content Thin Film Catalysts for Hydrogen Proton Exchange Membrane Fuel Cells
Václavů, Michal ; Matolín, Vladimír (advisor) ; Bystroň, Tomáš (referee) ; Neitzel, Armin (referee)
Novel type of catalyst for proton exchange membrane fuel cells anode is demonstrated. It is based on magnetron sputtered Pt-CeO2 a Pt-Sn-CeO2 mixed oxides. It is shown, that these materials allow to significantly decrease amount of platinum in the anode catalyst. The preparation method yields high amount of platinum in ionized form, especially Pt2+ , which is related to the high activity. Stability of these catalytic layers were investigated under conditions similar to fuel cell anode (humidified hydrogen at elevated temperature). Also interaction of hydrogen a water under UHV conditions were studied, demonstrating high stability of the Pt2+ species. In the last part of the work sputtered Pt-Co mixed catalyst were investigated to be used in the PEMFC cathode. It is demonstrated that at right conditions, the sputtered alloy catalyst improves mass activity on cathode by factor more than two.
High pressure CO and methanol oxidation study over nanopowders Rare Earth Oxides and platinum thin film catalysts
Rednyk, Andrii ; Matolín, Vladimír (advisor) ; Lykhach, Yaroslava (referee) ; Šmíd, Břetislav (referee)
Title: High pressure CO and methanol oxidation study over nanopowder Rare Earth Oxides and platinum thin film catalysts Author: Mgr. Andrii Rednyk Department: Department of Surface and Plasma Science Supervisor: Prof. RNDr. Vladimír Matolín, DrSc. matolin@mbox.troja.mff.cuni.cz Abstract: This doctoral thesis focuses on reactivity study of nanopowder rare earth oxides (REOs) and platinum based thin film catalysts using microreactor with high pressure reaction cell. REOs nanoparticles were prepared by new approach based on sol-gel chemistry. Magnetron sputtering technique was used for preparation of thin film samples. In the first part of the thesis CO oxidation on REOs and on Pt, PtOx thin films were performed. Among prepared REOs catalyst better activity exhibited alumina stabilized ceria, due to higher surface area. Both Pt and PtOx deposited on silicon substrate exhibited similar activity. When carbon (G-foil or C interlayer) is used as support, activity of Pt thin film decreases while PtOx preserves high activity. In the second part of the thesis steam reforming of methanol (SRM) and partial oxidation of methanol (POM) were performed on Pt thin films. It was shown that PtOx thin film exhibited superior activity compared to other samples with the same thickness. It is due to the reduction of platinum...
Low Platinum Content Thin Film Catalysts for Hydrogen Proton Exchange Membrane Fuel Cells
Václavů, Michal ; Matolín, Vladimír (advisor)
Novel type of catalyst for proton exchange membrane fuel cells anode is demonstrated. It is based on magnetron sputtered Pt-CeO2 a Pt-Sn-CeO2 mixed oxides. It is shown, that these materials allow to significantly decrease amount of platinum in the anode catalyst. The preparation method yields high amount of platinum in ionized form, especially Pt2+ , which is related to the high activity. Stability of these catalytic layers were investigated under conditions similar to fuel cell anode (humidified hydrogen at elevated temperature). Also interaction of hydrogen a water under UHV conditions were studied, demonstrating high stability of the Pt2+ species. In the last part of the work sputtered Pt-Co mixed catalyst were investigated to be used in the PEMFC cathode. It is demonstrated that at right conditions, the sputtered alloy catalyst improves mass activity on cathode by factor more than two.

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