Origin
of the Enhanced Electrocatalysis for Thermally
Controlled Nanostructure of Bimetallic Nanoparticles
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Abstract
The thermal annealing process is
a common treatment used after
the preparation step to enhance the electrocatalytic properties of
the oxygen reduction reaction (ORR). The structure of a Pt-based bimetallic
nanoparticle, which is significantly affected by the catalytic properties,
is reconstructed by thermal energy. We investigated the effect of
structural reconstruction induced by thermal annealing on the improvement
of the ORR using various physical and electrochemical methods. We
found that the structural evolution of PtNi nanoparticles, i.e., the
Pt–Ni ordering with the Pt shell and the surface reorientation
into the (111) facet, is the source of the enhanced ORR activity as
well as electrochemical stability through the thermal annealing. This
result confirms the crucial factors for the ORR properties by the
thermal annealing process and proposes a way to design advanced electrocatalysts