Tenkovrstvové katalyzátory pre použitie v elektrolyzéroch vody a regeneratívnych palivových článkoch s protónovo vodivou membránou

Predkladná dizertačná práca spadá do oblasti vodíkového hospodárstva a elektrochemického ukladania elektrickej energie. Konkrétne, skúma možnosti využitia magnetronového naprašovania pre depozíciu účínných tenkovrstvových anódových katalyzátorov s nízkym obsahom vzácnych kovov pre elektrolyzéry vody a regeneratívne palivové články s polymérnou membránou (PEM- WE a PEM-URFC). Motivácia výskumu je daná nutnosťou znížiť cenu týchto elektrochemických zariadení pred ich masovým prienikom na trh. Realizovalo sa množstvo experimentov dávajúcich do súvisu reálne zmeranú účinnosť v elektrochemickej cele s rôznym umiestnením tenkovrstvového katalyzátoru v rámci geometrie membrána-elektródového usporiadania, s rôznym zložením vysoko poréznej podvrstvy, či s rôznou chemickou štruktúrou samotného katalyzátoru. Široká paleta experimentálnych metód, ako napríklad elektrochemická impedančná spektroskopia, skenovacia elektrónová mikroskopia, či fotoelektrónová spektroskopia nám umožnili popísať komplexné fyzikálno-chemické javy zodpovedné za rôzne účinnosti v cele. Následujúca systematická optimalizácia viedla k príprave unikátneho PEM-WE anódového tenkovrstvového irídiového katalyzátoru s hrúbkou len 50 nm, neseného na optimalizovanej TiC podvrstve, ktorý bol výkonnostne zhodný s bežnými katalyzátormi, využívajúcimi...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...Katedra fyziky povrchů a plazmatuDepartment of Surface and Plasma ScienceMatematicko-fyzikální fakultaFaculty of Mathematics and Physic

Iontové katalyzátory pro životní prostředí

Katedra fyziky povrchů a plazmatuDepartment of Surface and Plasma ScienceMatematicko-fyzikální fakultaFaculty of Mathematics and Physic

Phosphorus poisoning during wet oxidation of methane over Pd@CeO2/graphite model catalysts

10siThe influence of phosphorus and water on methane catalytic combustion was studied over Pd@CeO2 model catalysts supported on graphite, designed to be suitable for X-ray Photoelectron Spectroscopy/Synchrotron Radiation Photoelectron Spectroscopy (XPS/SRPES) analysis. In the absence of P, the catalyst was active for the methane oxidation reaction, although introduction of 15% H2O to the reaction mixture did cause reversible deactivation. In the presence of P, both thermal and chemical aging treatments resulted in partial loss of activity due to morphological transformation of the catalyst, as revealed by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) analysis. At 600 °C the combined presence of PO43− and water vapor caused a rapid, irreversible deactivation of the catalyst. XPS/SRPES analysis, combined with operando X-ray Absorption Near Edge Structure (XANES) and AFM measurements, indicated that water induces severe aggregation of CeO2 nanoparticles, exposure of CePO4 on the outer layer of the aggregates and incorporation of the catalytic-active Pd nanoparticles into the bulk. This demonstrates a temperature-activated process for P-poisoning of oxidation catalysts in which water vapor plays a crucial role.partially_openembargoed_20171009Monai, Matteo; Montini, Tiziano; Melchionna, Michele; Duchoň, Tomáš; Kúš, Peter; Tsud, Nataliya; Prince, Kevin C.; Matolin, Vladimir; Gorte, Raymond J.; Fornasiero, PaoloMonai, Matteo; Montini, Tiziano; Melchionna, Michele; Duchoň, Tomáš; Kúš, Peter; Tsud, Nataliya; Prince, Kevin C.; Matolin, Vladimir; Gorte, Raymond J.; Fornasiero, Paol

Thin-film catalysts for proton exchange membrane water electrolyzers and unitized regenerative fuel cells

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

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

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..

Studium interakce Pd a Pt s oxidy cínu a ceru

1 je vhodným materiálom pre tenkovrstvové plynové senzory. Dopovaním takejto vrstvy platinou by sa mala zvýšiť jeho citlivosť. Predkladaná diplomová práca sa zaoberá optimalizáciou prípravy plynocitlivých vrstiev na báze resp. s hrúbkou pod . Dôraz je kladený na komplexnú fyzikálno-chemickú analýzu vzniknutých vrstiev a premeranie ich senzorických vlastností pre vodík. Vrstvy boli deponované metódou rádiofrekvenčného magnetrónového naprašovania z keramického terča a kovového terča a následne skúmané metódami XPS, AFM, SEM a XRD. Ukazuje sa, že platina sa vo vrstve nachádza v kovovom, ako aj zmesnom stave . Pri žíhaní, ktoré je nutné pre správne fungovanie senzora, sa chemický stav platiny menil. Po žíhaní pri sa zvýšilo množstvo zmesnej zložky a pri teplote sa platina nachádzala výhradne v oxidovanom stave. Senzorické vlastnosti vrstiev sa študovali na 2 typoch čipových platforiem (sklenených s chrómovými kontaktmi a safírových s platinovými kontaktmi). Napriek očakávaniam sa platinou dopované vrstvy javili menej citlivé, čo si vysvetľujeme tým, že platina sa vo vrstvách nachádzala v inom, ako kovovom stave. Oba typy vrstiev boli citlivejšie pri použití safírových substrátov, čo pravdepodobne súvisí so skutočnosťou, že vrstva na tejto platforme vykazovala kryštalickú štruktúru a kontakty boli z kovovej platiny.1 is a suitable material for thin-film gas sensors. Higher sensitivity could be achieved by platinum dopping of the layer. This work focuses on the optimalization of and thin film preparation by radio-frequency magnetron sputtering method. Subsequent analysis by means of XPS, AFM, SEM and XRD was carried out to determine physicochemical attributes of resulting layers. It appears that after the deposition, platinum within the layer is present in the metalic , as well as in the mixed chemical state. After the annealing process mixed state dominates over metalic state and after additional annealing platinum is present solely in oxidized form. Sensory response of layers for presence of hydrogen were examined on two different chip platforms (glass with chromium contacts and sapphire with platinum contacts). Contrary to expectations, the platinum dopped layers performed worse in comparison to the pure tin dioxide layers. This could be explained by the fact, that after annealing platinum within the layer was present mainly in the non-metalic form. Both and layers were more sensitive on sapphire platform, which could be associated with the crystal structure formed on its surface or with presence of metalic contacts.Department of Surface and Plasma ScienceKatedra fyziky povrchů a plazmatuFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult

Investigation of Pt-SnOx gas sensors

1 is a suitable material for thin-film gas sensors. Higher sensitivity could be achieved by platinum dopping of the layer. This work focuses on the optimalization of and thin film preparation by radio-frequency magnetron sputtering method. Subsequent analysis by means of XPS, AFM, SEM and XRD was carried out to determine physicochemical attributes of resulting layers. It appears that after the deposition, platinum within the layer is present in the metalic , as well as in the mixed chemical state. After the annealing process mixed state dominates over metalic state and after additional annealing platinum is present solely in oxidized form. Sensory response of layers for presence of hydrogen were examined on two different chip platforms (glass with chromium contacts and sapphire with platinum contacts). Contrary to expectations, the platinum dopped layers performed worse in comparison to the pure tin dioxide layers. This could be explained by the fact, that after annealing platinum within the layer was present mainly in the non-metalic form. Both and layers were more sensitive on sapphire platform, which could be associated with the crystal structure formed on its surface or with presence of metalic contacts

Thin-film catalysts for proton exchange membrane water electrolyzers and unitized regenerative fuel cells

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..