1 research outputs found
Synthesis and Characterization of Monodisperse Metallodielectric SiO<sub>2</sub>@Pt@SiO<sub>2</sub> Core–Shell–Shell Particles
Metallodielectric nanostructured
core–shell–shell
particles are particularly desirable for enabling novel types of optical
components, including narrow-band absorbers, narrow-band photodetectors,
and thermal emitters, as well as new types of sensors and catalysts.
Here, we present a facile approach for the preparation of submicron
SiO<sub>2</sub>@Pt@SiO<sub>2</sub> core–shell–shell
particles. As shown by transmission and scanning electron microscopy,
the first steps of this approach allow for the deposition of closed
and almost perfectly smooth platinum shells onto silica cores via
a seeded growth mechanism. By choosing appropriate conditions, the shell thickness could be adjusted
precisely, ranging from ∼3 to ∼32 nm. As determined
by X-ray diffraction, the crystalline domain sizes of the polycrystalline
metal shells were ∼4 nm, regardless of the shell thickness.
The platinum content of the particles was determined by atomic absorption
spectroscopy and for thin shells consistent with a dense metal layer
of the TEM-measured thickness. In addition, we show that the roughness
of the platinum shell strongly depends on the storage time of the
gold seeds used to initiate reductive platinum deposition. Further,
using polyvinylpyrrolidone as adhesion layer, it was possible to coat
the metallic shells with very homogeneous and smooth insulating silica
shells of well-controlled thicknesses between ∼2 and ∼43
nm. After depositing the particles onto silicon substrates equipped
with interdigitated electrode structures, the metallic character of
the SiO<sub>2</sub>@Pt particles and the insulating character of the
SiO<sub>2</sub> shells of the SiO<sub>2</sub>@Pt@SiO<sub>2</sub> particles
were successfully demonstrated by charge transport measurements at
variable temperatures