Cheap hydrogen fuel from seawater may be a step closer

Apr 29, 2010 by Lin Edwards report
Reaction of [(PY5Me2)MoI]2+ with water to form [(PY5Me2)MoO]2+ and release H2 and half an equivalent of I2. The release of hydrogen was confirmed by mass spectrometry. Image credit: Nature, doi:10.1038/nature08969.

(PhysOrg.com) -- A new catalyst has been developed to generate hydrogen from water cheaply, but the research was originally intended to make molecules that behaved like magnets. Hydrogen is a clean power source currently produced from natural gas, with carbon dioxide as a by-product. Producing hydrogen from water produces oxygen as a by-product instead.

Conventional catalysts capable of splitting water into and oxygen are generally too expensive or too weak to work on water effectively enough to produce hydrogen for an inexpensive fuel, but new research has developed a molybdenum catalyst that is robust and cheap enough to do the job, but still requires too much energy to be immediately useful. It does open up new possibilities for scientists to follow in the search for the perfect water-splitting catalyst.

One conventional means of splitting water into H2 and O2 is to use a platinum catalyst but the metal is far too expensive for the process to be commercially viable. Other methods use microbial enzymes called hydrogenases containing proteins using nickel and iron, but these methods are either too bulky, slow, or too inefficient to be successful on a commercial basis.

The new study by scientists at the University of California, Berkeley, aimed at combining metal atoms with organic molecular groups (called PY5) to produce molecules with the properties of bulk magnets. The researchers, led by Jeffrey Long, found that one of their molecules, a molybdenum-oxo complex, was capable of transferring . This is a major requirement of water-splitting systems, so they tested its ability to split water to generate and found it was highly successful.

The molybdenum compound was so successful it could work on or pure without additives. The compound is stable due to five bonds holding the molybdenum in place. Long said the molecule is stable for long periods in aqueous solutions, and they saw no degradation in over their three-day experiment. The molecule remains stable even when impurities, such as those found in seawater, are present. This would further reduce the cost since no organic acids or solvents are needed.

The compound’s stability makes it more durable than the nickel and iron compounds used previously, but it is slower than the natural hydrogenases and needs a higher electric voltage to operate. The group is now experimenting with different metals and "tweaking" the PY5 groups to see if they can improve the speed and efficiency and reduce the energy requirements. They are also looking at the possibility of coupling the system to solar-generated electricity to make it even more viable.

Explore further: Study identifies metal organic framework candidates for methane storage, fuels hope for natural gas cars

More information: A molecular molybdenum-oxo catalyst for generating hydrogen from water, Nature 464, 1329-1333 (29 April 2010), doi:10.1038/nature08969

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User comments : 11

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Shootist
1.8 / 5 (5) Apr 29, 2010
Cheap. Hydrogen. For. North America? Without having to mine nasty dirty molybdenum?

Build 100 1GW Fission plants and use either electrolysis or steam flashing to produce your "cheap" hydrogen. This route also allows you to recharge those battery powered cars and desalinate seawater for those idiots in Los Angeles.
El_Nose
2 / 5 (2) Apr 29, 2010
ahh -- that would not desalinate water at all. water is H2O and you are effectively stripping the H2 away to ge the hydrogen. Desalination strips ocean water of the ions or salts in the water -- either by reverse osmosis where water goes through a membrane and the salts stay on the other side -- or using heat to flash steam the water gather the gas and let it recondense to fresh water.

Either desalination method still dumps concentraded salt water back into the ocean in a localized area. which may potentially be harmful.

No, this article is talking about stripping the H2 from the H2O which produces more O2 , O3 as a byproduct. O3 is harder to produce as it normally need electricity to excite the eletrons to produce the triple bond. but O2 is normal oxygen.
shavera
1 / 5 (1) Apr 29, 2010
How is this a catalyst at all? If the oxygen replaces the iodine in the molecule, wouldn't it just be a chemical reaction? Don't catalysts just facilitate reactions while remaining unchanged themselves?

Shootist: what about mining "nasty dirty" uranium? or manufacturing plutonium? or storing the waste from 100 nuclear power plants. I support nuclear power, but don't pretend it isn't without it's cons as well.
Foundation
2 / 5 (1) Apr 29, 2010
Could you please explain your molybdenum mining comment? I don't understand what its use would be in the production of hydrogen.
I only know it's used in a lot of steel alloys and as a transportable parent isotope for a medical radio isotope (technetium-99)
But then again, I'm by no means an engineer.
ShadowRam
1 / 5 (1) Apr 29, 2010
Build 100 1GW Fission plants


Without having to mine nasty dirty uranium?
Your 'route' is also retarded.
sender
not rated yet Apr 30, 2010
What happened to plasma reformation, the UK MOD as well as other agencies worldwide went heavy into them in 2004, seems to have been put under the tables now.
DaveMart
not rated yet Apr 30, 2010
Adding solar to just about anything decreases, nor increases viability.
It is expensive relative to other energy resources and as it is not available all of the time to make use of the hydrogen producing equipment economically you would have to add expensive storage.
Throwing in solar is just a way of getting more funds by pressing the 'right' buttons.
stealthc
3 / 5 (2) Apr 30, 2010
catalysts are supposed to remain unchanged after a reaction, whoever wrote this article failed grade 9 science class.
Foundation
not rated yet Apr 30, 2010
Ouch, this'll teach me not to comment at night, I feel really stupid now (and it's well deserved)
Ignore my previous comment please.
chemgrad
not rated yet May 01, 2010
It is a catalyst if you add in a reductant (either sacrificial or a water oxidation catalyst). Once you add a reductant, electrons are transferred to the Mo-O species, forming water, and regenerating the catalyst.

You can't have a catalyst for an oxidation or reduction reaction without having another catalyst or a sacrifical species for the corresponding reduction or oxidation reaction, respectively.

The iodine complex is the one they made, and adding water creates the Mo-O species and H2. Giving this species a reductant turns the "O" in the species on the right into water, and regenerates the active Mo-H2O complex that can produce hydrogen.

Also, the whole "solar" thing is about an easy way to regenerate the catalyst, by making molecular photodiodes or using solar to run the reaction. Otherwise, all these "H2" production catalysts are stupid.

Protip: if you don't understand something, ask a question instead of insulting others and showing everyone how much an idiot you are.
Tan0r5
not rated yet May 01, 2010
Brilliant! A good way to reduce world population by using water to make fuel. Use all wastes instead. Convert by friction, no chemicals, no burning!

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