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dc.contributor.advisorRichards, Ryan
dc.contributor.advisorSullivan, Neal P.
dc.contributor.authorShinozaki, Kazuma
dc.date.accessioned2015-10-09T16:35:26Z
dc.date.accessioned2022-02-03T12:53:58Z
dc.date.available2016-04-05T04:18:44Z
dc.date.available2022-02-03T12:53:58Z
dc.date.issued2015
dc.identifierT 7884
dc.identifier.urihttps://hdl.handle.net/11124/20281
dc.description2015 Fall.
dc.descriptionIncludes illustrations (some color).
dc.descriptionIncludes bibliographical references.
dc.description.abstractAlthough the commercialization of automotive proton exchange membrane fuel cells (PEMFCs) is imminent, additional reduction in cathode platinum electrocatalyst loadings are being pursued to meet cost targets. Currently ~30 g of Pt dispersed on a carbon black produces a net power output of 100 kW in automotive FC stacks ($50/gPt; $1500 per 100 kW stack). In order to eliminate any question of available Pt resources, the consensus target for total Pt loading is ~0.1 gPt/kW and is roughly based on the current utilization estimates of platinum in catalytic convertors of gasoline powered engines. To achieve the target Pt loading, researchers are engaged in synthesizing novel oxygen reduction reaction (ORR) catalysts that exhibit an activity improvement of a factor of ~3–4. Rotating disk electrodes (RDEs) are being widely used as a screening tool to estimate the activity of the novel electrocatalysts synthesized in lab-scale (mg) quantities as candidates for PEMFCs. However, inconsistencies in measured ORR activity for baseline catalyst materials among labs often lower the reliability of novel catalysts activity values estimated by the RDE method. Therefore, to improve reliability of the RDE method, an investigation of measurement protocol parameters for the electrochemical area and ORR activity was conducted with down-selections based on the criteria of reproducibility, duration of experiments, impurity effects and magnitude of pseudo-capacitive background correction. Also, the effect of catalyst film formation method on RDE on the measured ORR activity has been studied based on a statistically significant number of independent measurements. In order to comprehensively understand the sources of the losses on measured ORR by the RDE method, we have for the first time carried out the breakdown of losses on the measured ORR activity by using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), SEM, EDX and surface profilometry. Our systematic analysis and breakdown of losses for different quality films revealed the importance of forming thin-uniform film to avoid underestimation of the activity due to O2 diffusion limitation within catalyst films. In addition, we found that Nafion ionomer (commonly used ionomer in PEMFC) lowers the ORR activity on Pt supported carbon catalysts as is observed on well-defined Pt based catalyst surfaces in literature.
dc.format.mediumborn digital
dc.format.mediumdoctoral dissertations
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado School of Mines. Arthur Lakes Library
dc.relation.ispartof2015 - Mines Theses & Dissertations
dc.rightsCopyright of the original work is retained by the author.
dc.subjectfuel cell
dc.subjectrotating disk electrode
dc.subjectoxygen reduction reaction
dc.subjectcatalyst
dc.titleOxygen reduction reaction activity measurements for proton exchange membrane fuel cell electrocatalysts utilizing rotating disk electrode method
dc.typeText
dc.contributor.committeememberTrewyn, Brian
dc.contributor.committeememberYang, Yongan
dc.contributor.committeememberPivovar, Bryan S.
dcterms.embargo.terms2016-04-05
dcterms.embargo.expires2016-04-05
thesis.degree.nameDoctor of Philosophy (Ph.D.)
thesis.degree.levelDoctoral
thesis.degree.disciplineChemistry and Geochemistry
thesis.degree.grantorColorado School of Mines
dc.rights.accessEmbargo Expires: 04/05/2016


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