We demonstrate the creation of Ag-based
bimetallic platonic Janus
nanostructures by confining galvanic replacement reaction at a nanoscale
interface on highly symmetrical nanostructures such as Ag nanocubes
and nanooctahedra using reactive microcontact printing (μCP).
The extent of galvanic replacement reaction can be controlled kinetically
to derive Janus nanostructures with Au nanodots deposited on either
one or multiple facets of Ag nanocubes. The selective deposition of
Au dots on a single facet of Ag nanocubes breaks the cubic symmetry
and brings about unique and anisotropic plasmonic responses. High-resolution
cathodoluminescence hyperspectral imaging of single Janus nanocube
demonstrates that surface plasmon resonances corresponding to Au and
Ag can be excited at different spots on one Janus nanocube. In addition,
we demonstrate the fabrication of alternating Janus/non-Janus segments
on 2D Ag nanowires by using a line-patterned polydimethylsiloxane
(PDMS) stamp for galvanic replacement. Aside from Au, Pt and Pd can
also be selectively deposited onto Ag nanocubes. These Janus nanostructures
may find important applications in the field of plasmon-enhanced catalysis