posted on 2024-03-09, 14:07authored byNagappan Ramaswamy, Zixiao Shi, Barr Zulevi, Geoff McCool, Nathan P. Mellott, Anusorn Kongkanand, Swami Kumaraguru, Michele L. Ostraat, David A. Muller, Nancy N. Kariuki, Deborah J. Myers, A. Jeremy Kropf
Improving the activity and durability of carbon-supported
platinum
catalysts for the oxygen-reduction reaction (ORR) in acidic electrolytes
is crucial to reducing the high overpotentials and power loss over
time in proton-exchange membrane fuel cells (PEMFCs). We found that
platinum nanoparticle catalyst deposited on an engineered carbon support
in the presence of zirconium enabled higher ORR activity and 25% better
retention in electrochemically active surface area (ECSA), thereby
improving durability. The use of zirconium precursor in the carbon
synthesis process led to the formation of atomically dispersed Zr
and ZrO2 nanoparticles on the support. Upon Pt deposition
and subsequent heat treatment, the ZrO2 particles preferentially
rearranged on and around the platinum nanoparticles in a chemically
reduced form as zirconium suboxide (ZrO2–x) surface-decorated nanoclusters, which mitigated Pt nanoparticle
coarsening. Analysis of the here-to-fore unknown catalyst structure
as well as its performance and durability in a PEM fuel cell membrane
electrode assembly (MEA) is discussed.