Facile
Synthesis of Palladium Right Bipyramids and
Their Use as Seeds for Overgrowth and as Catalysts for Formic Acid
Oxidation
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Abstract
Controlling
the shape and thus facets of metal nanocrystals is
an effective way to enhance their performance in catalytic reactions.
While Pd nanocrystals with a myriad of shapes have been successfully
prepared with good uniformity and in high yield, Pd right bipyramids
(RBPs) that have a singly twinned structure have been elusive. We
report a facile route based on polyol reduction for the synthesis
of Pd RBPs with purity >90% and sizes controlled in the range 5–15
nm. The success of our synthesis relies on the use of iodide ions
to manipulate the strength of an oxidative etchant and selectively
cap the Pd{100} facets. The as-prepared RBPs could serve as seeds
to generate a set of Pd nanocrystals with novel shapes and structures.
The RBPs also exhibited enhanced catalytic activity toward formic
acid oxidation, with a current density 2.5 and 7.1 times higher than
those of the single-crystal Pd nanocubes (which were also mainly covered
by {100} facets) and commercial Pd black, respectively