Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Size matters in nanocrystals' ability to adsorb/release gases

These are palladium nanocrystals.

Credit: Bardhan Laboratory
These are palladium nanocrystals.

Credit: Bardhan Laboratory

Abstract:
More efficient catalytic converters on autos, improved batteries and more sensitive gas sensors are some of the potential benefits of a new system that can directly measure the manner in which nanocrystals adsorb and release hydrogen and other gases.

Size matters in nanocrystals' ability to adsorb/release gases

Nashville, TN | Posted on August 8th, 2013

The technique, which was developed by Vanderbilt University Assistant Professor of Chemical and Biomolecular Engineering Rizia Bardhan, is described in a paper published online Aug. 4 by the journal Nature Materials.

In the last 30 years, there has been a tremendous amount of research studying nanocrystals - tiny crystals sized between one to 100 nanometers in size (a nanometer is to an inch what an inch is to 400 miles) - because of the expectation that they have unique physical and chemical properties that can be used in a broad range of applications.

One class of applications depends on nanocrystals' ability to grab specific molecules and particles out the air, hold on to them and then release them: a process called adsorption and desorption. Progress in this area has been hindered by limitations in existing methods for measuring the physical and chemical changes that take place in individual nanocrystals during the process. As a result, advances have been achieved by trial-and-error and have been limited to engineered samples and specific geometries.

"Our technique is simple, direct and uses off-the shelf instruments so other researchers should have no difficulty using it," said Bardhan. Collaborators in the development were Vanderbilt Assistant Professor of Mechanical Engineering Cary Pint, Ali Javey from the University of California, Berkeley and Lester Hedges, Stephen Whitelam and Jeffrey Urban from the Lawrence Berkeley National Laboratory.

The method is based on a standard procedure called fluorescence spectroscopy. A laser beam is focused on the target nanocrystals, causing them to fluoresce. As the nanocrystals adsorb the gas molecules, the strength of their fluorescent dims and as they release the gas molecules, it recovers.

"The fluorescence effect is very subtle and very sensitive to differences in nanocrystal size," she explained. "To see it you must use nanocrystals that are uniform in size." That is one reason why the effect wasn't observed before: Fabrication techniques such as ball milling and other wet-chemical approaches that have been widely used produce nanocrystals in a range of different sizes. These differences are enough to mask the effect.

To test their technique, the researchers studied hydrogen gas sensing with nanocrystals made out of palladium. They choose palladium because it is very stable and it readily releases adsorbed hydrogen. They used hydrogen because of the interest in using it as a replacement for gasoline. One of the major technical obstacles to this scenario is developing a safe and cost-effective storage method. A nanocrystal-based metal hydride system is one of the promising approaches under development.

The measurements they made revealed that the size of the nanocrystals have a much stronger effect on the rate that the material can adsorb and release hydrogen and the amount of hydrogen that the material can absorb than previously expected - all key properties for a hydrogen storage system. The smaller the particle size, the faster the material can absorb the gas, the more gas it can absorb and faster it can release it.

"In the past, people thought that the size effect was limited to sizes less than 15 to 20 nanometers, but we found that it extends up to 100 nanometers," said Bardhan.

The researchers also determined that the adsorption/desorption rate was determined by just three factors: pressure, temperature and nanocrystal size. They did not find that additional factors such as defects and strain had a significant effect as previously suggested. Based on this new information, they created a simple computer simulation that can predict the adsorption/desorption rates of various types and size ranges of nanocrystals with a variety of different gases.

"This makes it possible to optimize a wide range of nanocrystal applications, including hydrogen storage systems, catalytic converters, batteries, fuel cells and supercapacitors," Bardhan said.

The research was funded by Department of Energy grants KC0202020 and AC02-05CH11231.

####

For more information, please click here

Contacts:
David F. Salisbury

615-343-6803

Copyright © Vanderbilt 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:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Strength of hair inspires new materials for body armor January 18th, 2017

Self-assembling particles brighten future of LED lighting January 18th, 2017

Dressing a metal in various colors: DGIST research developed a technology to coat metal with several nanometers of semiconducting materials January 17th, 2017

Nanoparticle exposure can awaken dormant viruses in the lungs January 17th, 2017

Govt.-Legislation/Regulation/Funding/Policy

Strength of hair inspires new materials for body armor January 18th, 2017

Self-assembling particles brighten future of LED lighting January 18th, 2017

Nanoscale view of energy storage January 16th, 2017

Chemistry on the edge: Experiments at Berkeley Lab confirm that structural defects at the periphery are key in catalyst function January 13th, 2017

Discoveries

Strength of hair inspires new materials for body armor January 18th, 2017

Self-assembling particles brighten future of LED lighting January 18th, 2017

Dressing a metal in various colors: DGIST research developed a technology to coat metal with several nanometers of semiconducting materials January 17th, 2017

Nanoparticle exposure can awaken dormant viruses in the lungs January 17th, 2017

Announcements

Strength of hair inspires new materials for body armor January 18th, 2017

Self-assembling particles brighten future of LED lighting January 18th, 2017

Dressing a metal in various colors: DGIST research developed a technology to coat metal with several nanometers of semiconducting materials January 17th, 2017

Nanoparticle exposure can awaken dormant viruses in the lungs January 17th, 2017

Energy

Dressing a metal in various colors: DGIST research developed a technology to coat metal with several nanometers of semiconducting materials January 17th, 2017

Stability challenge in perovskite solar cell technology: New research reveals intrinsic instability issues of iodine-containing perovskite solar cells December 26th, 2016

Nanoscale 'conversations' create complex, multi-layered structures: New technique leverages controlled interactions across surfaces to create self-assembled materials with unprecedented complexity December 22nd, 2016

Safe and inexpensive hydrogen production as a future energy source: Osaka University researchers develop efficient 'green' hydrogen production system that operates at room temperature in air December 21st, 2016

Automotive/Transportation

Nanoscale view of energy storage January 16th, 2017

Illinois team advances GaN-on-Silicon for scalable high electron mobility transistors January 10th, 2017

Going green with nanotechnology December 21st, 2016

Scientists boost catalytic activity for key chemical reaction in fuel cells: New platinum-based catalysts with tensile surface strain could improve fuel cell efficiency December 19th, 2016

Battery Technology/Capacitors/Generators/Piezoelectrics/Thermoelectrics/Energy storage

Nanoscale view of energy storage January 16th, 2017

One step closer to reality: Devices that convert heat into electricity: Composite material yields 10 times -- or higher -- voltage output January 4th, 2017

STMicroelectronics Peps Up Booming Social-Fitness Scene with Smart Motion Sensors for Better Accuracy, Longer Battery Life, and Faster Time to Market January 2nd, 2017

Researchers produced nitrogen doped bimodal cellular structure activated carbon December 29th, 2016

Fuel Cells

Scientists boost catalytic activity for key chemical reaction in fuel cells: New platinum-based catalysts with tensile surface strain could improve fuel cell efficiency December 19th, 2016

It's basic: Alternative fuel cell technology reduces cost: Study sets performance targets for metal-free fuel cell membrane December 13th, 2016

Keeping electric car design on the right road: A closer look at the life-cycle impacts of lithium-ion batteries and proton exchange membrane fuel cells December 9th, 2016

Water vapor sets some oxides aflutter: Newly discovered phenomenon could affect materials in batteries and water-splitting devices October 3rd, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project