Structure of hydrogen storage molecule solved, once orientation of nearby ions elucidated

Feb 04, 2011
Diffraction studies provided the insights needed to understand key molecules in hydrogen storage

(PhysOrg.com) -- For nearly a century, nobody knew how the little molecule that’s in the middle of many of today’s hydrogen storage and release concepts was organized. Thanks to an interdisciplinary team of scientists at Pacific Northwest National Laboratory and Los Alamos National Laboratory, the structure of this molecule, known as DADB, has been determined. And DADB’s structure was exactly opposite of what was expected in more ways than one.

"The irony," said Dr. Tom Autrey, the PNNL scientist who led the research, "is that the structure could not be that complex." The challenge was in understanding how one structure, containing a pair of nitrogen and boron atoms surrounded by only 12 hydrogen atoms, stretched and twisted in the solid molecular crystal.

Running cars on fossil fuels presents growing problems, economically, politically, and environmentally. Replacing fossil fuels with hydrogen and fuel cells is an attractive option. Determining the structure of DADB, created at the initial stages when hydrogen is released from the popular material ammonia borane, allows scientists to accurately model and predict complex, molecular reactions in the solid state. Understanding the subtleties of the structure of DADB also provides insights into developing new materials with the perfect properties to store energy in chemical bonds for efficient fuel cell operations.

The team began by synthesizing the DADB using a new method they developed that allowed the molecular crystal to slowly form at room temperature. They used solid-state nuclear magnetic resonance (NMR) spectroscopy to study the molecule. The NMR spectrum of the molecular crystal was surprisingly different than the NMR spectrum of the molecular complex in solution. The team felt that the hydrogen atoms in the molecular crystal might be influencing the arrangement of atoms.

“Theoreticians couldn’t accurately predict the structure, and experimentalists weren’t getting all the information needed with NMR,” said Dr. Gregory Schenter, a chemical theorist on the study. “So, we used neutron diffraction to see the missing pieces. It took a while, but we got that ‘ah-ha’ moment.”

With the added diffraction data, they could arrange the atoms in a pattern that explained the results they’d seen. “Mark Bowden solved the 100-year-old puzzle,” said Autrey of his PNNL colleague. “He showed how the molecule’s structure was affected by the interactions with the neighboring molecules.”

This research resulted in two different arrangements of borohydride (BH4-) giving the molecule its unique twisted structure.

This work is part of a series of broader efforts at PNNL to answer the fundamental questions around how to activate hydrogen for use in catalytic reactions as well as energy storage in chemical bonds for use in fuel cell applications. These fundamental studies are needed if the United States is to develop novel methods to store energy from solar and other intermittent clean energy sources.

Explore further: Water leads to chemical that gunks up biofuels production

More information: Bowden M, DJ Heldebrant, A Karkamkar, T Proffen, GK Schenter, and T Autrey. 2010. “The diammoniate of diborane: Crystal structure and hydrogen release.” Chemical Communications 46, 8564-8566.

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StillWind
2.4 / 5 (8) Feb 04, 2011
How dumb does one have to be to continue to waste money on hydrogen?
Simple physics proves that hydrogen is not and cannot be a fuel "source".
It will always take more energy to produce free hydrogen than it returns.
Hydrogen is one of the most inefficient energy storage systems known, and is simply a way to tax dumb people who aren't smart enough to know better.
David_Lang
3.7 / 5 (3) Feb 04, 2011
Knowledge about solid hydrides is a significant scientific contribution to materials science regardless to the potential to hydrogen powered vehicles. Hydrogen would be a great source of fuel considering it's potentially endless supply when solar water splitting cells are used to create it.
Sanescience
1 / 5 (1) Feb 05, 2011
"Running cars on fossil fuels presents growing problems, economically, politically, and environmentally. Replacing fossil fuels with hydrogen and fuel cells is an attractive option. "

Fail. Bio-diesel has it all over molecular hydrogen. Hydrogen is not an efficient carrier of energy. Just spent a while on a different topic board trying to dissuade people from this "fools gold" form of research.

I don't think people care enough about the environment to really look into why hydrogen fails.
thingumbobesquire
1 / 5 (1) Feb 05, 2011
What we really need is to replace the wasteful interstate highway system with maglev rail (while simultaneously building the water project NAWAPA.) But we are too busy bailing out London and Wall Street speculators.
MorituriMax
not rated yet Feb 05, 2011
"Running cars on fossil fuels presents growing problems, ..., politically, and ...."

Politically... great, which is probably why we don't harvest all our energy from the sun. Or anything else that would solve global problems. Politicians.

I wonder how long till we have a belt of satellites around the sun gathering energy and spaced so the Earth is always close to enough to gather the energy we need.

#*!*$ Politicians.
MorituriMax
not rated yet Feb 05, 2011
How dumb does one have to be to continue to waste money on hydrogen?
I guess as dumb as you or anyone else that doesn't know that pretty much everything in the universe starts at hydrogen and builds from there.
Sanescience
not rated yet Feb 05, 2011
How dumb does one have to be to continue to waste money on hydrogen?
I guess as dumb as you or anyone else that doesn't know that pretty much everything in the universe starts at hydrogen and builds from there.


That, is a very illogical statement, and technically wrong to!

Along those lines of reasoning everything started as high energetic radiation. And radiation, hard and soft, still floods the universe, doesn't mean it would be a good thing for our environment.

Nature already figured out how to use hydrogen, combine it with some carbon so you can keep a hold of it! The carbon in bio-diesel is "carbon neutral", it has better energy density and safer than hydrogen.

Why are we spending money re-inventing the energy carrier/storage "wheel"? Because it is a way to squeeze money out of the government.
Sanescience
not rated yet Feb 05, 2011
Knowledge about solid hydrides is a significant scientific contribution to materials science regardless to the potential to hydrogen powered vehicles. Hydrogen would be a great source of fuel considering it's potentially endless supply when solar water splitting cells are used to create it.


I'm sure the raw knowledge and expertise has its merits. But presenting Hydrogen as anything but an inefficient carrier of energy (not a source) hides the essential issue that our environment will be more polluted for it's development until that far future, if ever.

For example, if instead of loosing about 50% of the energy from solar-voltaic collectors to manufacture hydrogen, just put it directly into the grid and turn off a coal power plant. Stated another way, keeping the coal power plant online so you can make hydrogen from solar is not just inefficient, it pollutes the environment.
Burnerjack
not rated yet Feb 10, 2011
@ Sanescience : Well said indeed. Unfortunately, the top of energy generation and use has largely been swampped by the "religeon" of "Saving The Planet".
I too harbor the husbandry instinct to take care of the enviroment but am concerned about the charlatans and merchants ever so eager and so far successful at exploiting the ideology of youth.
The answer (IMHO) is to shift to an electric based economy and transport system. How to power this infrastructure? Well I'm glad you asked... Geothermal scource power. Totaly pragmatical. The answer is under our feet. Whether Geothermal Steam/electric or at the other end of the spectrum, ground scource Stirling generators. Power 365/24/7. One comment I read was to utilize decommissioned fossil fuel wells to futher reduce capital costs. Brilliant! I ask myself "why not?"
So far, the only answer was "who stands to gain vs who stands to lose". Nothing technical seems to be an issue.