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Characterization of Catalyst Materials for PEMFCs using Analytical Electron Microscopy

The goal of current research is probing the relationship between catalyst features and
the fuel cell performance with a range of in-depth structural analysis. The study
investigated different catalyst systems including core-shell structured catalyst, catalysts
with unique carbon-transition metal oxide supports.
PtRu catalysts nanoparticles with unique core-shell structure, one of the most
practical catalysts in PEMFC technology, have been successfully obtained with the
evidence from the characterization results. It is found that the enhanced CO oxidation
may be achieved through the interactions between the Pt shell and Ru core atoms, which
can modify the electronic structure of the Pt surface by the presence of subsurface Ru
atoms or by disrupting the Pt surface arrangement. Furthermore, the possibility of
presence of the compressive strain within the Pt rich shell is proved by the lattice
measurements, which could significantly affect the catalytic activity.
Pt catalysts supported on complex oxide and carbon support were studied to
investigate the relationship between the catalyst and its support. Observations from
STEM images and HAADF and energy dispersive X-ray spectrometry demonstrate the
preferential distribution of Pt nanoparticles on the hybrid supports, which include Nb2O3
/ C, Ta2O5 / C, (Nb2O3+TiOx) / C, (Ta2O5+TiOx) / C, and (WO3+TiOx)/C). Such
evidence indicates the interaction between the catalyst and support is based on the
presence of an interconnected oxide network over the carbon support and the presence of
Pt strongly connected to the oxide network. In addition, using electron energy loss
spectroscopy (EELS), the electronic structure of the catalyst support under various
conditions was also studied to provide further evidence of the strong metal support
interaction effect. / Thesis / Doctor of Philosophy (PhD)

Identiferoai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/18450
Date11 1900
CreatorsNan, Feihong
ContributorsBotton, Gianluigi, Materials Science and Engineering
Source SetsMcMaster University
LanguageEnglish
Detected LanguageEnglish
TypeThesis

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