New hydrogen-storage method discovered

November 22, 2009
This schematic shows the structure of the new material, Xe(H2)7. Freely rotating hydrogen molecules (red dumbbells) surround xenon atoms (yellow). Credit: Nature Chemistry

Scientists at the Carnegie Institution have found for the first time that high pressure can be used to make a unique hydrogen-storage material. The discovery paves the way for an entirely new way to approach the hydrogen-storage problem. The researchers found that the normally unreactive, noble gas xenon combines with molecular hydrogen (H2) under pressure to form a previously unknown solid with unusual bonding chemistry. The experiments are the first time these elements have been combined to form a stable compound. The discovery debuts a new family of materials, which could boost new hydrogen technologies.

The paper is published in the November 22, 2009, advanced online publication of Nature Chemistry.

has some intriguing properties, including its use as an anesthesia, its ability to preserve biological tissues, and its employment in lighting. Xenon is a noble gas, which means that it does not typically react with other elements.

As lead author Maddury Somayazulu, research scientist at Carnegie's Geophysical Laboratory, explained: "Elements change their configuration when placed under pressure, sort of like passengers readjusting themselves as the elevator becomes full. We subjected a series of gas mixtures of xenon in combination with hydrogen to high pressures in a diamond anvil cell. At about 41,000 times the pressure at sea level (1 atmosphere), the atoms became arranged in a lattice structure dominated by hydrogen, but interspersed with layers of loosely bonded xenon pairs. When we increased pressure, like tuning a radio, the distances between the xenon pairs changed-the distances contracted to those observed in dense metallic xenon."

The researchers imaged the compound at varying pressures using X-ray diffraction, infrared and Raman spectroscopy. When they looked at the xenon part of the structure, they realized that the interaction of xenon with the surrounding hydrogen was responsible for the unusual stability and the continuous change in xenon-xenon distances as pressure was adjusted from 41,000 to 255,000 atmospheres.

Why was the compound so stable? "We were taken off guard by both the structure and stability of this material," said Przemek Dera, the lead crystallographer who looked at the changes in electron density at different pressures using single-crystal diffraction. As electron density from the xenon atoms spreads towards the surrounding hydrogen molecules, it seems to stabilize the compound and the xenon pairs.

"Xenon is too heavy and expensive to be practical for use in applications," remarked Somayazulu. "But by understanding how it works in this situation, researchers can come up with lighter substitutes."

"It's very exciting to come up with new hydrogen-rich compounds, not just for our interest in simple molecular systems, but because such discoveries can be the foundation for important new technologies," commented Russell Hemley, director of the Geophysical Laboratory and a co-author. "This hydrogen-rich solid represents a new pathway to forming novel storage compounds and the new pressure-induced chemistry opens the possibility of synthesizing new energetic materials."

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Source: Carnegie Institution

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1 / 5 (1) Nov 22, 2009
They really should have kept this to themselves for a while... Oh well, the race is on!
Is this conformation of xenon actually a new discovery? Because I would have expected HUGE response to a discovery such as this
not rated yet Nov 22, 2009
Not to sound naive... BUT the practical application is to be able to use this compound at lesser atmospheres than 41,000. I would guess. It is lovely science but there must be a direct application to hydrogen use in the "real" world.

I recall that the "boys at MIT" have developed a method of storing Hydrogen that does not require an increase of atmospheric pressure to such a great degree but I can't find the article.

1.5 / 5 (2) Nov 22, 2009
Gee, makes the consequences of automobile accidents take on an entire new meaning! And how heavy would the fuel tank have to be to withstand 41000 atmospheres?
not rated yet Nov 23, 2009
Is this conformation of xenon actually a new discovery? Because I would have expected HUGE response to a discovery such as this

Xenon has been known to form compounds for quite some time now: http://en.wikiped...ompounds
not rated yet Nov 23, 2009
None of these things are coming close to storing hydrogen by linking it to carbon.
Aluminum hydride (AlH3)is as bulky and inconvenient as firewood.
not rated yet Nov 23, 2009
I do not quite understand how the Xenon will be separated from the Hydrogen to make it an economical source of Hydrogen?
4 / 5 (4) Nov 23, 2009
Gack! Hydrogen is a trendy idea pushed by business and people who want to sell the outlandishly expensive equipment and infrastructure to support it.

First, Hydrogen is an energy *storage* medium, not an energy source. Our current infrastructure is designed to handle oil. If we were to replace fossil fuel sources with renewable eco friendly bio fuel sources, we could reuse our current gigantic infrastructure. Hydrogen is very corrosive and would require expensive maintenance of machinery involved in its usage far above our current infrastructure.
5 / 5 (3) Nov 23, 2009
Second, It's bigest advertised benefit is when burned it produces water, not CO2. HOWEVER... Hydrogen is impossible to fully contain, and the more widespread it's use becomes the more hydrogen leaks into the atmosphere. When hydrogen leaks, it goes up to the high atmosphere where it is going to react to deplete earths ozone protection layer. And the reaction creates water in the dry upper layers where it will act as a global warming gas hundreds of times more potent than CO2.

Third, Hydrogen is dangerous to handle and requires a lot of expensive equipment and technical know how to use. Regular people will be completely unable to perform their own repairs on such systems. Bio fuels and oils will allow all the current mechanics to keep their jobs and average people can still work on their vehicles.
3 / 5 (2) Nov 23, 2009
Oil dependance is over, this proves that pressure reformation for complex hydrocarbons is well feasible.
5 / 5 (2) Nov 23, 2009
Hydrogen is not a good solution to replace oil, stop wasting your time.
Make much better batteries that is a solution that doesn't need a replacement in the future and can be very safe.
not rated yet Nov 23, 2009
... When hydrogen leaks, it goes up to the high atmosphere where it is going to react to deplete earths ozone protection layer. And the reaction creates water in the dry upper layers where it will act as a global warming gas hundreds of times more potent than CO2...

Is that true? Can provide a reference, please. Thanks.
1 / 5 (1) Nov 23, 2009
As other s have pointed out, hydrogen is a poor carrier of energy. It's inefficient to manufacture (it's not appearing, it must be made with other energy). There are much better energy carriers like electricity stored in batteries. Also conversion from hydrogen to motive energy is more wasteful than from electricity. So in every stage hydrogen loses primary energy. We can not store hydrogen properly in a car and we don't have the hydrogen delivery infra. We know how to store electricity and we have the means to distribute it. And when we develop better, cleaner ways to manufacture electricity, every el-driven mile will be cleaner. And batteries, albeit currently expensive, are very cheap when one looks what fuel cells do cost. And the alternative use of hydrogen in ICE is even more wasteful.

While we wait for the batteries to get cheaper, bring us those gasoline-diesel-hybrid engines that promise 50% thermal efficiencies.
Nov 24, 2009
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5 / 5 (1) Nov 24, 2009
I never post, but this seems so much more feasible, although a hydrogen infrastucture is decades away compared with electricity that is effectively on tap.

not rated yet Nov 24, 2009
@pt30: Effects of increased Hydrogen in the environment has come up in quite a few conversations over the years. I did a quick Google search and there are quite a few links, here is one that came up right away:

not rated yet Nov 25, 2009
Can someone please either verify or refute the legend of the picture: it says the red "dumbbells" are hydrogen and the yellow figures are xenon atoms. My thought was xenon atoms are much bigger than hydrogen ones so the yellow should be the H2 and the red Xe. I hope I don't turn out a (red) "dumbbell" about this... :~(

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