posted on 2023-11-14, 15:06authored bySe-Ho Kim, Hosun Jun, Kyuseon Jang, Pyuck-Pa Choi, Baptiste Gault, Chanwon Jung
Proton-exchange membrane fuel cells hold promise as energy
conversion
devices for hydrogen-based power generation and storage. However,
the slow kinetics of oxygen reduction at the cathode imposes the need
for highly active catalysts, typically Pt or Pt based, with a large
available area. The scarcity of Pt increases the deployment and operational
cost, driving the development of novel highly active material systems.
As an alternative, a Rh-doped PtNi nanoparticle has been suggested
as a promising oxygen reduction catalyst, but the three-dimensional
distributions of constituent elements in the nanoparticles have remained
unclear, making it difficult to guide property optimization. Here,
a combination of advanced microscopy and microanalysis techniques
is used to study the Rh distribution in the PtNi nanoparticles, and
Rh surface segregation is revealed, even with an overall Rh content
below 2 at. %. Our findings suggest that doping and surface chemistry
must be carefully investigated to establish a clear link with catalytic
activity that can truly be established.