Home > Press > To make better fuel cells, study the defects
 |
Provided/Chen Lab
When Amplex Red connects with a gold catalyst the structure is changed to make a fluorescent molecule that immediately emits a flash of light, showing where the catalytic event took place. Right, electron microphoto of a single gold nanorod, encased in a poirus silica shell. The shell keeps rods from clumping together and allows experimenters to use heat to clean away a coating that forms when the rods are created. |
Abstract:
Engineers trying to improve fuel-cell catalysts may be looking in the
wrong place, according to new research at Cornell.
To make better fuel cells, study the defects
Ithaca, NY | Posted on February 20th, 2012
There is growing interest in forming the catalysts that break down fuel
to generate electricity into nanoparticles. Nanoparticles provide a
larger surface area to speed reactions, and in some cases, materials
that are not catalytic in bulk become so at the nanoscale.
These nanoparticles, typically just a few tens of nanometers (nm) wide,
are not neat little spheres, but rather jagged chunks, like microscale
gravel, and researchers have found that they can correlate catalytic
activity with information about the number and type of their surface
facets. But they may be looking at the forest and ignoring the trees.
"People measure the activity of a sample and then try to understand by
using facet information," said Peng Chen, associate professor of
chemistry and chemical biology. "The message we want to deliver is that
surface defects [on the facets] dominate the catalysis."
Chen's research is reported Feb. 19 in the online edition of the
journal Nature Nanotechnology.
Instead of particles, Chen's research group studied catalytic events on
gold "nanorods" up to 700 nm long, effectively letting them see how
activity varies over a single facet. Gold acts as a catalyst to convert
a chemical called Amplex Red into resorufin, which is fluorescent.
Each time a catalytic event occurs, the newly created molecule of
resorufin emits a flash of light that is detected by a digital camera
looking through a microscope. A flash typically appears as several
pixels, and additional computer processing averages their brightness to
pinpoint the actual event to within a few nanometers. The researchers
call the technique "super-resolution microscopy." After flooding a
field of nanorods with a solution of Amplex Red, they made a "movie"
with one frame every 25 milliseconds.
The researchers found more catalytic events near the middle of a rod,
tapering off toward the ends and a jump back up at the ends. They also
found variation in the amount of activity from one rod to another, even
though all the rods have the same types of facets.
To explain the results, they proposed that activity is higher in areas
where there are more surface defects. The nanorods are made by growing
gold crystals from a small "seed" crystal, growing outward from the
center to the ends, Chen explained, and more defects form at the
beginning of the process.
"Knowledge of the surface facets ... is insufficient to predict
reactivity," the researchers said in their paper. "Surface defects …
can also play a dominant role."
The findings with a gold catalyst and fluorescent molecules should be
equally applicable to other catalysts, including those used in fuel
cells and for pollution remediation, Chen said.
The research was supported in part by the Army Research Office, the
National Science Foundation (NSF), the Department of Energy and the
Alfred P. Sloan Foundation. Part of the work was carried out at the
Cornell Center for Materials Research and the Cornell Nanoscale Science
and Technology Facility, both supported by NSF.
####
For more information, please click here
Contacts:
Bill Steele
(607) 255-7164
Copyright © Cornell University
If you have a comment, please
Contact us.
Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.
Bookmark:
News and information
Aspen Aerogels Announces $22.5 Million Private Placement May 18th, 2013
NanoInk, Inc. Assets To Be Sold May 18th, 2013
Beautiful "flowers" self-assemble in a beaker: Elaborate nanostructures blossom from a chemical reaction perfected at Harvard May 17th, 2013
Scientists capture first direct proof of Hofstadter butterfly effect May 17th, 2013
Govt.-Legislation/Regulation/Funding/Policy
Beautiful "flowers" self-assemble in a beaker: Elaborate nanostructures blossom from a chemical reaction perfected at Harvard May 17th, 2013
Artificial Forest for Solar Water-Splitting: Berkeley Lab Researchers Report First Fully Integrated Artificial Photosynthesis Nanosystem May 17th, 2013
Moth-Inspired Nanostructures Take the Color Out of Thin Films May 17th, 2013
NIA Public Briefing: Nanotechnology and the Council of Europe May 17th, 2013
Discoveries
Beautiful "flowers" self-assemble in a beaker: Elaborate nanostructures blossom from a chemical reaction perfected at Harvard May 17th, 2013
Artificial Forest for Solar Water-Splitting: Berkeley Lab Researchers Report First Fully Integrated Artificial Photosynthesis Nanosystem May 17th, 2013
Moth-Inspired Nanostructures Take the Color Out of Thin Films May 17th, 2013
Scientists capture first direct proof of Hofstadter butterfly effect May 17th, 2013
Announcements
Aspen Aerogels Announces $22.5 Million Private Placement May 18th, 2013
NanoInk, Inc. Assets To Be Sold May 18th, 2013
NIA Public Briefing: Nanotechnology and the Council of Europe May 17th, 2013
Scientists capture first direct proof of Hofstadter butterfly effect May 17th, 2013
Military
Using clay to grow bone: Researchers use synthetic silicate to stimulate stem cells into bone cells May 15th, 2013
Flawed Diamonds Promise Sensory Perfection: Berkeley Lab researchers and their colleagues extend electron spin in diamond for incredibly tiny magnetic detectors May 10th, 2013
Researcher Construct Invisibility Cloak for Thermal Flow: Copper-Silicon Plate Deflects Heat / Optical Process Transferred to Thermodynamics / Basis for Future Heat Management in Microchips and Components May 8th, 2013
Improved material for ‘laser welding’ of tissue in intestinal surgery May 8th, 2013
Fuel Cells
Researchers develop unique method for creating uniform nanoparticles May 6th, 2013
Surface diffusion plays a key role in defining the shapes of catalytic nanoparticles April 8th, 2013
Nanoparticles Combined with Light Reverses Rusting April 1st, 2013
Hydrogen stores wind and solar energy: Innovative "Power-to-Gas" concepts at Hannover Messe March 7th, 2013