Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Unlocking the Secrets of Titanium, a "Key" that Assists Hydrogen Storage

26.07.2004


New research may lead to better catalysts for hydrogen fuel cells



Scientists at the U.S. Department of Energy’s Brookhaven National Laboratory and the New Jersey Institute of Technology have taken steps toward understanding how a titanium compound reacts with a hydrogen-storage material to catalyze the release and re-absorption of hydrogen. Their results, appearing in the July 19, 2004, issue of Applied Physics Letters, may help scientists learn how similar catalysts work, improve their performance, and possibly develop more efficient storage materials for hydrogen fuel cells.

In the late 1990s, scientists discovered that adding, or “doping,” a small amount of titanium to sodium aluminum hydride, a hydrogen storage compound (also known as sodium alanate), allows it to reversibly release and re-absorb hydrogen. In a sense, the titanium acts like a molecular “key,” a crucial component that facilitates hydrogen absorption and allows the reaction to proceed more rapidly. Until now, however, the nature of that reaction was not well understood.


“We found that the titanium resides on the surface of sodium alanate as a titanium aluminum compound called titanium aluminide, rather than entering the bulk material and replacing other atoms or occupying empty spots within the lattice,” said the study’s lead author, Brookhaven physicist Jason Graetz.

To make their finding, Graetz and his collaborators first prepared two titanium-doped samples by mechanically mixing titanium chloride and sodium alanate using a planetary mill, a device that grinds substances together using marble-sized metal spheres. They then prepared two additional samples from each doped sample (for a total of six): a dehydrided sample (containing no absorbed hydrogen) and a hydrided sample. By working with both types, the researchers were able to study the titanium’s properties before and after hydrogen absorption. This gave them one more way to determine the titanium’s role in the reaction.

The group probed the samples with high-energy x-rays at the National Synchrotron Light Source at Brookhaven, a facility that produces intense beams of x-ray, ultraviolet, and infrared light for research. Because every compound and element on Earth absorbs x-rays differently, having a unique “signature,” the researchers were able to compare the six sample signatures to those of different titanium compounds and pure titanium. From this, they determined that the titanium chloride reacted with sodium alanate to form titanium aluminide.

“Our finding is the first step toward an even more interesting discovery: determining exactly how titanium aluminide helps the hydride release and re-absorb hydrogen,” Graetz said. “Understanding that mechanism may help us identify better catalysts for the sodium alanate system and help us find dopants for new compounds that are currently impractical energy-storage materials, due to the high temperatures and pressures required for the release and re-absorption of hydrogen.”

Sodium alanate is one of several metal-based hydrogen storage materials, called metal hydrides, being investigated for use in hydrogen fuel cells. A fuel cell works like a battery: Hydrogen atoms enter the negative terminal and split into their constituent particles, protons and electrons. The protons pass through the cell to the positive terminal, while the electrons leave the cell as a stream of electric current that can power a car or appliance, for example. The electrons then re-enter the cell at the positive terminal and reunite with the protons and oxygen to form water molecules.

The known hydrides are impractical for fuel cells, which require lightweight materials with high storage capacities, because they are quite heavy and have relatively low storage capacities (less than five percent hydrogen by weight). However, they have more potential than compressed hydrogen gas or liquid hydrogen, which pose explosion and freezing risks. These forms of hydrogen must be stored in tanks under very high pressure or at temperatures cold enough to liquefy the oxygen in air.

This research was funded by Brookhaven’s Laboratory Directed Research and Development (LDRD) Program and the National Science Foundation.

Karen McNulty Walsh | EurekAlert!
Further information:
http://www.bnl.gov

More articles from Physics and Astronomy:

nachricht Magnetic field traces gas and dust swirling around supermassive black hole
22.02.2018 | Royal Astronomical Society

nachricht UMass Amherst physicists contribute to dark matter detector success
22.02.2018 | University of Massachusetts at Amherst

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Stiffness matters

22.02.2018 | Life Sciences

Magnetic field traces gas and dust swirling around supermassive black hole

22.02.2018 | Physics and Astronomy

First evidence of surprising ocean warming around Galápagos corals

22.02.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>