ja050693p_si_001.pdf (2.85 MB)
Magnetic and Porous Nanospheres from Ultrasonic Spray Pyrolysis
journal contribution
posted on 2005-08-31, 00:00 authored by Won Hyuk Suh, Kenneth S. SuslickWe have used an inexpensive high-frequency ultrasound generator from a household humidifier
to create a useful source for ultrasonic spray pyrolysis and produced submicrometer silica particles that
are porous on the nanometer scale. By using two heated zones, we first initiate polymerization of organic
monomers in the presence of silica colloid, which creates in situ a composite of silica with an organic
polymer, followed by a second heating to pyrolyze and remove the polymer. The morphology and surface
area of the final porous silica are controlled by varying the silica-to-organic monomer ratio. In a single flow
process, ferromagnetic cobalt nanoparticles can be easily encapsulated in the porous silica, and the resulting
nanospheres are extremely resistant to air oxidation. Products were characterized by SEM, (S)TEM, EDS,
XPS, and SQUID.