We report a method for synthesizing
and studying shape-controlled,
single Pt nanoparticles (NPs) supported on carbon nanoelectrodes.
The key advance is that the synthetic method makes it possible to
produce single, electrochemically active NPs with a vast range of
crystal structures and sizes. Equally important, the NPs can be fully
characterized, and, therefore, the electrochemical properties of the
NPs can be directly correlated to the size and structure of a single
shape. This makes it possible to directly correlate experimental results
to first-principles theory. Because just one well-characterized NP
is analyzed at a time, the difficulty of applying a theoretical analysis
to an ensemble of NPs having different sizes and structures is avoided.
In this article, we report on two specific Pt NP shapes having sizes
on the order of 200 nm: concave hexoctahedral (HOH) and concave trapezohedral
(TPH). The former has {15 6 1} facets and the latter {10 1 1} facets. The electrochemical properties of these single NPs for the
formic acid oxidation (FAO) reaction are compared to those of a single,
spherical polycrystalline Pt NP of the same size. Finally, density
functional theory, performed prior to the electrochemical studies,
were used to interpret the experimental results of the FAO experiments.