National Repository of Grey Literature 33 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
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.
Novel nanocatalysts for fuel cells I: new type bipolar fuel cells
Švenda, Petr ; Matolín, Vladimír (advisor) ; Khalakhan, Ivan (referee)
There is a greater focus on the alternative sources of energy due to the energetic crisis recently. One of the many ways are the fuel cells, which are based on generating electricity by oxidating the hydrogen. A prominent place is occupied by cells with polymer membrane called PEMFC, which are especially suited for mobile applications due to their low operating temperature. The bigest obstacle for commercial use of the PEMFC is the big amount of platinum required for their production. It is necessary to reduce their cost by means of reducing the amount of used platinum while maintaining the same efficiency. One of the ways is using platinum in alloy with another metal instead of using pure platinum. This thesis addresses the alloy of Pt-Co prepared by magnetron sputtering, which exhibits desirable properties. Adding cobalt decreases the potential barrier that must be overcome for catalytic reaction to proceed. This results in higher specific power output of the fuel cell. The goal of this thesis is to examine in more detail the properties of Pt-Co in comparison with Pt.
Investigation of thin films for hydrogen fuel cells
Komárková, Zuzana ; Matolín, Vladimír (advisor) ; Nováková, Jaroslava (referee)
Clean and highly efficient energy source has long been sought to solve energy and environmental problems. Fuel cells, which convert the chemical energies sto- red in fuel directly into electrical energy, are expected to be the key technology. In this thesis the catalytic active layers (specifically Pt, PtCo, PtNi, PtRu) for Direct methanol fuell cell (DMFC) are studied. We have evaluated PtCo as the best cathode catalysts. We have significantly reduced the amount of platinum as well as the power loss at higher concentrations of methanol. The sputtered PtCo catalyst is comparable power density in comparison with commercial Pt catalyst while the specific power per gram of platinum is several times higher. The speci- fic power of our anode catalyst layers is comparable to reference catalysts. Our findings are useful for future improvements of the anode catalyst layer for DMFC.

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