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Patent Number: |
6695986 |
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Case ID: |
82330 |
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Patent Title:
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Electrocatalytic enhancement with catalyst-modified carbon-silica composite aerogels |
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Status: |
ACTIVE |
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Status Date: |
2/26/2004 10:46:32 AM |
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Issue Date:
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2/24/2004 |
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Filed Date:
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9/25/2002 |
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Serial #:
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253602 |
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Assignee Name:
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The United States of America as represented by the Secretary of the Navy (Washington, DC) |
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Inventor(s):
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Rolison, Debra R. ,Anderson, Michele L. ,Stroud, Rhonda M. |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to composite aerogels and, more
particularly, to an electrically conductive, mesoporous architecture that
improves access of a catalyst to a reactant thereby leading to enhanced
catalytic activity.
2. Background of the Invention
High-surface-area carbon blacks serve as effective solid supports to
disperse nanoscale noble metals for use as catalysts (e.g., for
hydrogenation or dehydrogenation reactions) and electrocatalysts for
oxidation and reduction reactions in fuel cells, and to thereby increase
efficiency and reduce costs. In fuel cells, despite high surface areas of
the electron-conducting carbon support and effective dispersion of the Pt
electrocatalysts, self-agglomeration of the carbon particles within
practical electrode structures limits the approach of fuel and oxidant to
the active sites, such th . . . . More |
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An electrically conductive composite is provided having a mesoporous
architecture that improves the accessibility of a nanoscopic catalyst,
supported on conductive carbon, to a mass-transported reactant, or
substrate, thereby leading to enhanced catalytic activity. In particular,
the composite is useful for a new class of fuel-cell electrode
architectures based on a composite aerogel that improves the accessibility
of a carbon-supported Pt electrocatalyst to methanol (MeOH), leading to
higher MeOH oxidation activities than observed at the native carbon
supported Pt electrocatalyst. The composite comprises a nanoscopic Pt
electrocatalyst, a carbon black electron-conducting support, and a silica
aerogel.
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What is claimed is:
1. A method of forming an electrically conductive composite, said method
comprising the steps of:
a) providing a loosely packed bed of a desired amount of catalyst-modified
carbon powder;
b) dispensing about-to-gel colloidal silica over the catalyst-modified
carbon bed;
c) allowing the silica sol to permeate the catalyst-modified carbon bed;
d) allowing the silica sol to completely perfuse throughout the
catalyst-modified carbon bed;
e) forming a wet composite gel comprising the catalyst-modified carbon
colloidal silica;
f) drying the wet composite gel at a supercritical temperature for a
specific pore fluid filling in order to form a composite aerogel.
2. The method according to claim 1, wherein the catalyst-modified carbon is
a preformed metal-modified carbon powder.
3. The method according to claim 1, wherein the catalyst modified carbon is
nanoscale-Pt . . . . More |
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