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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...
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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...
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Investigation of Pt-SnOx gas sensors
Kúš, Peter ; Matolín, Vladimír (advisor) ; Zahoran, Miroslav (referee)
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.
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