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:4/27/2016)... , ... April 27, 2016 , ... ... is pleased to announce the appointment of John Tilton as Chief Commercial Officer.  ... Director and one of the founding commercial leaders responsible for the commercialization of ...
(Date:4/27/2016)... ... 2016 , ... PathSensors, Inc., a leading environmental testing company, ... assist PathSensors in expanding the use of the company’s CANARY® technology in the ... for the detection of harmful pathogens, including a number of bacteria, viruses, toxins, ...
(Date:4/27/2016)... ... 2016 , ... Global Stem Cells Group CEO Benito Novas announced ... of GSCG affiliate Kimera Labs in Miami. , In 2004, Ross received his Ph.D. ... for hematologic disorders and the suppression of graft vs. host disease (GVHD) under UM ...
(Date:4/27/2016)... MedDay, a biotechnology company focused on ... of Catherine Moukheibir as Chairman of its Board of Directors. ... Jacques Garaud , who contributed to the rapid development of ... Catherine started her career in strategy consulting and investment ... London .  She held C-Suite level roles in some ...
Breaking Biology Technology:
(Date:3/17/2016)... ABI Research, the leader in transformative ... market will reach more than $30 billion by ... Consumer electronics, particularly smartphones, continue to boost the ... reach two billion shipments by 2021 at a ... Research Analyst at ABI Research. "Surveillance is also ...
(Date:3/15/2016)... -- Yissum Research Development Company of the Hebrew ... Hebrew University, announced today the formation of Neteera ... human biological indicators. Neteera Technologies has completed its first ... ... emissions from sweat ducts, enables reliable and speedy biometric ...
(Date:3/14/2016)... HANOVER , Allemagne, March 14, 2016 /PRNewswire/ ... http://www.apimages.com ) - --> - ... ) - --> ... les solutions biométriques, fournit de nouveaux lecteurs d,empreintes ... lecteur LF10 de DERMALOG sera utilisé pour produire ...
Breaking Biology News(10 mins):