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Porous carbon sponges prepared
by aerosol technique
Since the discovery of buckyballs and carbon nanotubes, there has been
intense interest inpreparing carbon materials of various morphologies
and structures. Now, graduate student Sara E. Skrabalak and chemistry professor Kenneth S. Suslick at the University of Illinois at Urbana-Champaign
have discovered a way to prepare porous carbon sponges by heating
a chemical mist from an ordinary home humidifier.
The prepared materials have much larger pores than conventional carbon
materials and could thus be used in adsorbent, catalytic and electrochemical
applications in which large molecules are involved. This new route to
mesoporous (2 to 20 nanometers) and macroporous (greater than 20nm)
carbon powders dramatically improves on conventional preparation methods.
Traditional carbon blacks are made by charring wood or other natural
products, but these have extremely small pore structures. Other larger
pore carbons have been prepared by tedious templating methods in which
a sacrificial material, such as nanoparticles of silica, are mixed with
a carbon precursor, heated to consolidate the precursor, and then treated
with caustic chemicals to remove the sacrificial template. With their
technique, however, Suslick and Skrabalak thermally decompose organic
compounds using ultrasonic spray pyrolysis to create a carbon/salt composite;
washing with water easily removes the salt, revealing the porous carbon
Ultrasonic spray pyrolysis uses a mist of micron-sized droplets from
a humidifier. The droplets are delivered where the water evaporates
and dissolved substances react, precipitate, or decompose to form product.
This technique has allowed for the continuous, inexpensive production
of micro- and nano-sized powders. With this latest work, Skrabalak and
Suslick have expanded this technique to the production of carbon materials.
This new synthetic route is simple, easily scaled-up and can be adapted
to other materials.
“Having big pores, these easily made porous carbons could be used
as adsorbents for environmental remediation or as solid supports for
industrially important catalysts,” Skrabalak said. “We have
collaborative work under way with Korean researchers that shows great
promise for fuel cell electrodes.”
This new route to porous carbons is to be reported in the Oct. 4 issue
of the Journal of the American Chemical Society. The work has been funded
by the National Science Foundation.
Editor's note: To reach Kenneth S. Suslick, call 217-333-2794; e-mail: firstname.lastname@example.org.