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 Applicability of dynamic facilitation theory to binary hard disk systems
08.12.2016 | Nagoya Institute of Technology

nachricht Will Earth still exist 5 billion years from now?
08.12.2016 | KU Leuven

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: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Closing the carbon loop

08.12.2016 | Life Sciences

Applicability of dynamic facilitation theory to binary hard disk systems

08.12.2016 | Physics and Astronomy

Scientists track chemical and structural evolution of catalytic nanoparticles in 3-D

08.12.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>