Navigation Links
Ames Laboratory researchers solve fuel-cell membrane structure conundrum
Date:12/11/2007

AMES, Iowa Fuel-cell cars are reaching commercial viability in todays increasingly eco-conscious society, but despite their promise, even scientists have struggled to explain just how the fuel-cells central component the proton exchange membrane really works.

However, a team of researchers at the U.S. Department of Energys Ames Laboratory has offered a new model that provides the best explanation to date for the membranes structure and how it functions. And armed with that information, scientists should be able to build similar fuel-cell membrane materials that are less expensive or have different properties, such as higher operating temperatures.

A fuel cell works by pumping hydrogen gas through the proton exchange membrane. In the process, the hydrogen gives up electrons in the form of electricity, then combines with oxygen gas to form water as the by-product. It can also work in reverse when current is applied, water is split into its component gases, hydrogen and oxygen.

The model proposed by Ames Laboratory scientists Klaus Schmidt-Rohr and Qiang Chen, and detailed in the Dec. 9 issue of the journal Nature Materials, looked specifically at Nafion, a widely used perfluorinated polymer film that stands out for its high selective permeability to water and protons. Schmidt-Rohr, who is also a professor of chemistry at Iowa State University, suggests that Nafion has a closely packed network of nanoscale cylindrical water channels running in parallel through the material.

From nuclear magnetic resonance (NMR), we know that Nafion molecules have a rigid backbone structure with hair-like defects along the chain, Schmidt-Rohr said, but we didnt know just how these molecule were arranged. Some have proposed spheroidal water clusters, others a web-like network of water channels.

Our theory is that these hydrophobic (water-hating) backbone structures cluster together, he continued, to form long rigid cylinders about 2.5 nanometers in diameter with the hydrophilic hairs to the inside of the water-filled tubes.

Though the cylinders in different parts of the sample may not align perfectly, they do connect to create water channels passing through the membrane material, which can be 10s of microns thick. Its this structure of relatively wide diameter channels, densely packed and running mostly parallel through the material that helps explain how water and protons can so easily diffuse through Nafion, almost as easily as water passing through water Schmidt-Rohr said.

To unlock the structure mystery, Schmidt-Rohr turned to mathematical modeling of small-angle X-ray and neutron scattering, or SAXS/SANS. X-ray or neutron radiation is scattered by the sample and the resulting scattering pattern is analyzed to provide information about the size, shape and orientation of the components of the sample on the nanometer scale.

Using an algorithm known as multidimensional Fourier transformation, Schmidt-Rohr was able to show that his model of long, densely packed channels closely matches the known scattering data of Nafion. Mathematical modeling of other proposed structures, in which the water clusters have other shapes or connectivities, did not match the measured scattering curves.

Our model also helps explain how conductivity continues even well below the freezing point of water, Schmidt-Rohr said. While water would freeze in the larger channels, it would continue to diffuse in the smaller-diameter pores.

Schmidt-Rohr added that additional analysis is needed to determine how the cylinders connect through the membrane.


'/>"/>

Contact: Kerry Gibson
kgibson@ameslab.gov
515-294-1405
DOE/Ames Laboratory
Source:Eurekalert

Related biology technology :

1. Pharmatek Adds Cytotoxic and High-Potent Drug Development Capabilities to San Diego Laboratory
2. BioMarin Licenses Technology From Leading Cystic Fibrosis Research Laboratory at the University of California, San Francisco
3. ARUP Laboratories and Premier Extend Contract for Reference Laboratory Testing Services
4. Sigma-Aldrich and Lab Manager Magazine Present Webinar On Laboratory Environmental, Health and Safety Compliance Strategies
5. AviaraDx Announces CAP Accreditation of Its Laboratory Operations
6. Instrumentation Laboratory Receives FDA Clearance to Expand the Intended Use for HemosIL(R) D-Dimer HS Assay
7. New White Paper Details Six Steps to Investigate and Prevent Laboratory Accidents
8. Codexis Opens Singapore Laboratory
9. Stem Cell Leader Beike Biotech and Chinas Tsinghua University Receive US$4 Million for Stem Cell Reprogramming Laboratory
10. Researchers improve ability to write and store information on electronic devices
11. Long-awaited international ethical guidelines for biobank researchers
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:7/18/2017)... ... July 18, 2017 , ... Nanomedical Diagnostics, ... development, announces the launch of a new NTA biosensor chip for use with ... study the kinetics of polyhistidine-tagged (His-tagged) molecules quickly and reliably. , “Recombinant ...
(Date:7/18/2017)... Basel, Switzerland (PRWEB) , ... July 18, 2017 ... ... for R&D, today announced that Merck, a leading science and technology company, has ... develop innovative therapeutics for the therapeutic areas of Oncology, Immunology, and Neurodegenerative Diseases. ...
(Date:7/18/2017)... ... July 18, 2017 , ... Blood centers traditionally see a dangerous drop ... summer is a struggle for community blood centers as high schools are out and ... of Commerce is teaming up with the South Texas Blood & Tissue ...
(Date:7/18/2017)... ... July 18, 2017 , ... Recently recognized by CIO ... announces the migration of its flagship cloud-based product Planet Life Cycle – a ... work management system that merges strategic and financial planning with execution. The solution ...
Breaking Biology Technology:
(Date:6/23/2017)... and ITHACA, N.Y. , June ... Cornell University, a leader in dairy research, today announced ... designed to help reduce the chances that the global ... onset of this dairy project, Cornell University has become ... Sequencing the Food Supply Chain, a food safety initiative ...
(Date:5/16/2017)... , May 16, 2017   Bridge ... health organizations, and MD EMR Systems , ... development partner for GE, have established a partnership ... Portal product and the GE Centricity™ products, including ... EMR. These new integrations will ...
(Date:4/18/2017)... April 18, 2017  Socionext Inc., a global expert in SoC-based ... edge server, the M820, which features the company,s hybrid codec technology. ... by Tera Probe, Inc., will be showcased during the upcoming Medtec ... show at the Las Vegas Convention Center ... Click here ...
Breaking Biology News(10 mins):