Surface Decoration of Platinum Catalysts by ZrO_2–<i>x</i> Nanoclusters for Durable Fuel Cell Applications

Abstract

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.