Cathodic Corrosion of a Bulk Wire to Nonaggregated Functional Nanocrystals and Nanoalloys

A key
enabling step in leveraging the properties of nanoparticles
(NPs) is to explore new, simple, controllable, and scalable nanotechnologies
for their syntheses. Among “wet” methods, cathodic corrosion
has been used to synthesize catalytic aggregates with some control
over their size and preferential faceting. Here, we report on a modification
of the cathodic corrosion method for producing a range of nonaggregated
nanocrystals (Pt, Pd, Au, Ag, Cu, Rh, Ir, and Ni) and nanoalloys (Pt50Au50, Pd50Au50, and AgxAu100–x) with potential for scaling up the production rate. The method employs
poly­(vinylpyrrolidone) (PVP) as a stabilizer in an electrolyte solution
containing nonreducible cations (Na+, Ca2+),
and cathodic corrosion of the corresponding wires takes place in the
electrolyte under ultrasonication. The ultrasonication not only promotes
particle–PVP interactions (enhancing NP dispersion and diluting
locally high NP concentration) but also increases the production rate
by a factor of ca. 5. Further increase in the production rate can
be achieved through parallelization of electrodes to construct comb
electrodes. With respect to applications, carbon-supported Pt NPs
prepared by the new method exhibit catalytic activity and durability
for methanol oxidation comparable or better than the commercial benchmark
catalyst. A variety of AgxAu100–x nanoalloys are characterized by ultraviolet–visible
absorption spectroscopy and high-resolution transmission electron
microscopy. The protocol for NP synthesis by cathodic corrosion should
be a step toward its further use in academic research as well as in
its practical upscaling.