Navigation Links
Ames Laboratory researchers solve fuel-cell membrane structure conundrum

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
DOE/Ames Laboratory

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:
(Date:6/27/2016)... ... June 27, 2016 , ... Rolf ... join the faculty of the University of North Carolina Kenan-Flagler Business School ... and entrepreneurship at UNC Kenan-Flagler, with a focus on the school’s international efforts, ...
(Date:6/24/2016)... , ... June 24, 2016 , ... While the majority ... as the Cary 5000 and the 6000i models are higher end machines that use ... height of the spectrophotometer’s light beam from the bottom of the cuvette holder. ...
(Date:6/23/2016)... , June 23, 2016 /PRNewswire/ - FACIT ... Ontario biotechnology company, Propellon Therapeutics ... development and commercialization of a portfolio of first-in-class ... Epigenetic targets such as WDR5 represent an exciting ... significantly in precision medicine for cancer patients. Substantial ...
(Date:6/23/2016)... NEW YORK , June, 23, 2016  The ... students to envision new ways to harness living systems ... of Modern Art (MoMA) in New York ... more than 130 participating students, showcased projects at MoMA,s ... included Paola Antonelli , MoMA,s senior curator of ...
Breaking Biology Technology:
(Date:6/2/2016)... Perimeter Surveillance & Detection Systems, Biometrics & ... & Other Service  The latest report from ... of the global Border Security market . Visiongain ... billion in 2016. Now: In November 2015 ... and hardware technologies for advanced video surveillance. ...
(Date:5/12/2016)... , May 12, 2016 ... just published the overview results from the Q1 wave ... the recent wave was consumers, receptivity to a program ... data with a health insurance company. "We ... to share," says Michael LaColla , CEO of ...
(Date:4/26/2016)... India and LONDON ... Infosys Finacle, part of EdgeVerve Systems, a product ... and Onegini today announced a partnership to integrate ... solutions.      (Logo: ... to provide their customers enhanced security to access ...
Breaking Biology News(10 mins):