Hydrogen from acidic water: Researchers develop potential low cost alternative to platinum for splitting water

Feb 09, 2012
Using a molybdenite complex and thePY5Me2 ligand, Berkeley Lab researchers synthesized a molecule that mimics catalytically active triangular molybdenum disulfide edge-sites. The result is an entire layer of catalytically active material. Molybdenum atoms are shown as green, sulfur as yellow. Credit: Courtesy of Berkeley Lab

A technique for creating a new molecule that structurally and chemically replicates the active part of the widely used industrial catalyst molybdenite has been developed by researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab). This technique holds promise for the creation of catalytic materials that can serve as effective low-cost alternatives to platinum for generating hydrogen gas from water that is acidic.

Christopher Chang and Jeffrey Long, chemists who hold joint appointments with Berkeley Lab and the University of California (UC) Berkeley, led a research team that synthesized a molecule to mimic the triangle-shaped molybdenum disulfide units along the edges of crystals, which is where almost all of the takes place. Since the bulk of molybdenite is relatively inert from a catalytic standpoint, molecular analogs of the catalytically active edge sites could be used to make new materials that are much more efficient and cost-effective catalysts.

"Using , we've been able to capture the functional essence of molybdenite and synthesize the smallest possible unit of its proposed catalytic active site," says Chang, who is also an investigator with the Howard Hughes Medical Institute (HHMI). "It should now be possible to design new catalysts that have a high density of active sites so we get the same catalytic activity with much less material."

Says Long, "Inorganic solids, such as molybdenite, are an important class of catalysts that often derive their activity from sparse active edge sites, which are structurally distinct from the inactive bulk of the molecular solid. We've demonstrated that it is possible to create catalytically active molecular analogs of these sites that are tailored for a specific purpose. This represents a conceptual path forward to improving future catalytic materials."

Chang and Long are the corresponding authors of a paper in the journal Science describing this research titled "A Molecular MoS2 Edge Site Mimic for Catalytic Hydrogen Generation." Other authors are Hemamala Karunadasa, Elizabeth Montalvo, Yujie Sun and Marcin Majda.

Jeffrey Long, Christopher Chang and Hemamala Karunadasa are paving the way for the creation of catalytic materials that can serve as effective low-cost alternatives to platinum for generating hydrogen gas from water. Credit: Photo by Roy Kaltschmidt, Berkeley Lab Public Affairs

Molybdenite is the crystalline sulfide of molybdenum and the principal mineral from which molybdenum metal is extracted. Although commonly thought of as a lubricant, molybdenite is the standard catalyst used to remove sulfur from petroleum and natural gas for the reduction of sulfur dioxide emissions when those fuels are burned. Recent studies have shown that in its nanoparticle form, molybdenite also holds promise for catalyzing the electrochemical and photochemical generation of hydrogen from water. Hydrogen could play a key role in future renewable energy technologies if a relatively cheap, efficient and carbon-neutral means of producing it can be developed.

Currently, the best available technique for producing hydrogen is to split water molecules into molecules of hydrogen and oxygen using platinum as the catalyst. However, with platinum going for more than $2,000 an ounce, the market is wide open for a low cost alternative . Molybdenite is far more plentiful and about 1/70th the cost of platinum, but poses other problems.

"Molybdenite has a layered structure with multiple microdomains, most of which are chemically inert," Chang says. "High-resolution scanning tunneling microscopy studies and theoretical calculations have identified the triangular molybdenum disulfide edges as the active sites for catalysis; however, preparing molybdenite with a high density of functional edge sites in a predictable manner is extremely challenging."

Chang, Long and their research team met this challenge using a pentapyridyl ligand known as PY5Me2 to create a molybdenum disulfide molecule that, while not found in nature, is stable and structurally identical to the proposed triangular edge sites of molybdenite. It was shown that these synthesized molecules can form a layer of material that is analogous to constructing a sulfide edge of molybdenite.

"The electronic structure of our molecular analog can be adjusted through ligand modifications," Long says. "This suggests we should be able to tailor the material's activity, stability and required over-potential for proton reduction to improve its performance."

In 2010, Chang and Long and Hemamala Karunadasa, who is the lead author on this new Science paper, used the PY5Me2 ligand to create a molybdenum-oxo complex that can effectively and efficiently catalyze the generation of hydrogen from neutral buffered water or even sea water. Molybdenite complexes synthesized from this new molecular analog can just as effectively and efficiently catalyze from acidic water.

"We're now looking to develop molecular analogs of active sites in other catalytic materials that will work over a range of pH conditions, as well as extend this work to photocatalytic systems" Chang says.

Adds Long, "Our molecular analog for the molybdenite active site might not be a replacement for any existing catalytic materials but it does provide a way to increase the density of active sites in inorganic solid and thereby allow us to do more with less."

Explore further: Building the ideal rest stop for protons

More information: www.sciencemag.org/content/335/6069/698.abstract

Related Stories

Chemists spray their way to better catalysts

Jul 11, 2005

Using a technique called ultrasonic spray pyrolysis, researchers at the University of Illinois at Urbana-Champaign have created an improved catalyst for removing smelly sulfur-containing compounds from gasoline ...

First molybdenite microchip

Dec 05, 2011

(PhysOrg.com) -- Molybdenite, a new and very promising material, can surpass the physical limits of silicon. EPFL scientists have proven this by making the first molybdenite microchip, with smaller and more ...

Cheap hydrogen fuel from seawater may be a step closer

Apr 29, 2010

(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 ...

Recommended for you

Nature inspires a greener way to make colorful plastics

12 hours ago

Long before humans figured out how to create colors, nature had already perfected the process—think stunning, bright butterfly wings of many different hues, for example. Now scientists are tapping into ...

New catalyst converts carbon dioxide to fuel

14 hours ago

Scientists from the University of Illinois at Chicago have synthesized a catalyst that improves their system for converting waste carbon dioxide into syngas, a precursor of gasoline and other energy-rich products, bringing ...

Building the ideal rest stop for protons

Jul 29, 2014

Where protons, or positive charges, decide to rest makes the difference between proceeding towards ammonia (NH3) production or not, according to scientists at Pacific Northwest National Laboratory (PNNL) and ...

Cagey material acts as alcohol factory

Jul 29, 2014

Some chemical conversions are harder than others. Refining natural gas into an easy-to-transport, easy-to-store liquid alcohol has so far been a logistic and economic challenge. But now, a new material, designed ...

User comments : 22

Adjust slider to filter visible comments by rank

Display comments: newest first

Telekinetic
1 / 5 (2) Feb 09, 2012
For decades, I've been searching for a method of burning hydrogen fuel in my car on an as-needed basis. Creating enough hydrogen to run an engine exclusively on it is illusive and many say impossible because it would violate thermodynamics. There are a number of tinkerers on the net who have claimed to have licked the problem, but the devices look clumsy and raise my suspicions. Then there was the lore of an inventor named Stanley Meyer who developed a hydrogen-powered car, but died under mysterious circumstances, so it remains to be seen. This molybdenite catalyst would probably only provide a trickle of what would be needed.
Shootist
2 / 5 (1) Feb 09, 2012
@TeeK:
This isn't magic, why look to magic to solve it?

It isn't hard to build a H2 powered car.

What's hard is storing and transporting the H2. That, and there are no hydrogen mines.

If you want a hydrogen based energy economy in North America, build 100 1000MW fission plants and crack sea water. You can spend the 20 years it will take to build the nukes developing efficient storage and transport methodologies.

Callippo
1 / 5 (6) Feb 09, 2012
It's just another research, which would become obsolete already if only the researchers wouldn't guarded their jobs with ignorance of cold fusion. http://www.infini...mit.html
TabulaMentis
1 / 5 (5) Feb 09, 2012
Top-down approaches will never match the efficiency of bottom-up technology. Dark energy and dark matter can split H2O cheaply. That is the bottom-up approach.
Telekinetic
1 / 5 (2) Feb 09, 2012
@TeeK:
This isn't magic, why look to magic to solve it?

It isn't hard to build a H2 powered car.

What's hard is storing and transporting the H2. That, and there are no hydrogen mines.

If you want a hydrogen based energy economy in North America, build 100 1000MW fission plants and crack sea water. You can spend the 20 years it will take to build the nukes developing efficient storage and transport methodologies.


I don't want to drive around in the Hindenburg, thanks just the same. If you re-read my post, I say "on an as-needed basis." That means I'm producing enough hydrogen while running the car. That WILL require something akin to magic.

@ Callippo:
When? I have a limited amount of time left on this earth let alone on the road.
Callippo
1 / 5 (5) Feb 09, 2012
When? I have a limited amount of time left on this earth let alone on the road.
The limited human lifespan becomes serious brake of further evolution, as many people aren't motivated to think in broader horizon. Not to say about politicians who are elected every few years.
Telekinetic
1 / 5 (2) Feb 09, 2012
When? I have a limited amount of time left on this earth let alone on the road.
The limited human lifespan becomes serious brake of further evolution, as many people aren't motivated to think in broader horizon. Not to say about politicians who are elected every few years.

Actually, with cutting-edge anti-aging strategies, I plan to make it into 2100. So maybe by then, my horizon will be broadened by cold fusion!
Urgelt
1 / 5 (2) Feb 09, 2012
Shootist, you think 20 years, or 200 years, will get us to dense, safe, efficient hydrogen storage methods?

I wish I could share your optimism.

Hydrogen is the smallest possible molecule. It wriggles past any seals we can make pretty easily; losses from storage cut deeply into efficiency. Molecular binding and releasing of hydrogen requires mass, consumes energy and can degrade; it's much worse than batteries. Pressurization looks good until you notice the seal problem and the even more serious problem of energy expenditure increasing hyperbolically as you pressurize the containment vessel. And we haven't even gotten into safety.

And you want to bet that if we build 100 nuclear reactors to manufacture hydrogen, we'll somehow figure out how to store, transport, and distribute hydrogen produced by them?

I'll save you some trouble. Use your nuclear power plants to generate electricity. Distribution problem, solved. Now all we need is better batteries. Those are coming.
Callippo
1.8 / 5 (5) Feb 09, 2012
Believe it or not, carbon hydrides, i.e. gasoline is still the most effective way of hydrogen storage, not to say about energy density. One liter of safe diesel, which is nearly inflammable at room temperature stores 38.6 MJ/liter, whereas hydrogen dangerously compressed at 700 bars only 5.6 MJ/liter (it's 5x higher pressure, than the pressure inside of common steal flasks used in welding machines). Even lithium air battery is more effective, not to say about energy efficiency of hydrogen conversion to electricity and back. Hydrogen economy is just another hoax promoted with lobby of researchers involved, similar to lobby of GMO or biofuels.

http://en.wikiped..._density
Telekinetic
5 / 5 (1) Feb 09, 2012
Jeez, Callippo, you just gave the oil companies a way of claiming to be green!
pietrocecchi
not rated yet Feb 10, 2012
I'm confident that this research will lead to the cheapest H2's production.
I gonna sponsor it!... :)

Very interesting article, for me, fellows.
Go ahead, Berkeley.
djr
1.5 / 5 (2) Feb 10, 2012
Hydrogen economy is just another hoax" Jeez - why does anything related to alternative energy, or global warming always have to bring out the conspiracy theorists?? Science is working on many fronts right now related to energy/transporttion etc. Many of the major car companies are working with hydrogen fuel cells. They are ultra expensive - but like many of the technologies - there is great promise. It is not a conspiracy! - they are working on it - if we hang with it - the technologies will evolve - and we will see which pans out as the most appropriate.
Callippo
2 / 5 (1) Feb 10, 2012
Hydrogen is not an alternative energy (source), until most of hydrogen is produced just with using of classical fossil fuels. Hydrogen economy is salary generator only.
djr
3.5 / 5 (2) Feb 11, 2012
"Hydrogen economy is salary generator only." Do you even know what you are trying to say? You can run a fuel cell on hydrogen. You can obtain hydrogen many different ways - steam reformation of methane, break down water with hydrolysis etc. So how is that you see hydrogen as a salary generator only? You just talk nonsense!! If I can reform methane into hydrogen, store it in a tank, use it to run a fuel cell (or an internal combustion engine) - and voila - I have a car. The economics is a whole different story - but the engineers are working on it. What will we be driving 50 years from now? I have no idea - but I am willing to have an open mind - and let the engineers do their magic. You should try an open mind some time Callippo - it is very refreshing.
djr
2.5 / 5 (2) Feb 11, 2012
To the nay sayers - check out Coca-Cola's fleet of hydrogen powered fork lifts. I am guessing the engineers and economists at this very successful private corporation know something you do not.
http://www.fuelce...eet.aspx
This is a neat quote - "the technology increases productivity by 15% on average and lowers operational costs by up to 30%."
Callippo
not rated yet Feb 11, 2012
The economics is a whole different story - but the engineers are working on it.

Nope, the economics is whole ground of hydrogen energetic economy.

http://cr4.global...her-Hoax

http://knol.googl...car-hoax

I can reform methane into hydrogen, store it in a tank, use it to run a fuel cell and I have a car
You can do it with methane or gasoline directly. We can produce the electricity in thermoelectric generators and/or we can burn the methane in combustion engines directly.
Callippo
2 / 5 (1) Feb 11, 2012
If we cannot save money with using of hydrogen, why we are doing it at all? The only answer is the job generation for researchers and private companies involved in it, when hydrogen energetic research is subsidized with government.
xen_uno
not rated yet Feb 11, 2012
Hydrogen economy seems like much less a hoax than cold fusion, so be careful what you call a hoax ...
djr
not rated yet Feb 11, 2012
"Nope, the economics is whole ground of hydrogen energetic economy." No it is not. There are many factors that determine which vehicles we choose. Economics and efficiency are not the only issues. Current problem with an EV is range. Will we overcome that problem with engineering? It is a pretty sure thing that we will. Current problem with hydrogen is cost, and efficiency. Labs all around the world are working on these issues. Where will we be 50 years from now??? I am tired of the conspiracy theorists feeling they have to put down our efforts to understand and improve our world. If Rossi has new energy system for us that will advance our world - bring it on - show us the money. Let the engineers that are working on other approaches such as hydrogen do their job. Enough with the conspiracy talk.
Callippo
1 / 5 (1) Feb 11, 2012
If Rossi has new energy system for us that will advance our world - bring it on - show us the money
This is a demagogic and toxic approach. For example at MIT the COP>10 was demonstrated. http://world.std....cft.html The cold fusion effects are real, they do produce energy - they just need a coordinated responsible research.

The future of human civilization is not a problem of Andrea Rossi. It's a problem of all of us. But many of people, I mean the researchers involved in another competitive areas realized, the finding of cold fusion will not help them, it can threat their jobs, salary, social positions, et cetera. And they decided to boycott it as a single man.
The problem is always the same: just the people, who cold help the cold fusion research, have the equipment for it are the most dismissive against it - because it interferes with their own plans about energetic future of civilization. And they will not help it, until they will not be motivated into it financially
Callippo
1 / 5 (1) Feb 11, 2012
am tired of the conspiracy theorists feeling they have to put down our efforts to understand and improve our world.
This is simply funny. It's just you who refuses to understand what's hidden beneath the cold fusion and improve our world - not me. Hydrogen economy will not and cannot improve our world, because it's an energy conversion technology - not an energy production technology. Without reliable and safe actual source of energy it will not help anything. If you would be REALLY interested about future of your world, you wouldn't refer to Rossi and his technology at all. This technology promising COP ~ 6 is insignificant here at all. We have experiments with COP > 10 demonstrated at MIT before journalists and students. Why do you refer Andrea Rossi? This is just a cunning behavior: you know very well, Rossi is cryptic and as such untrustworthy - so you're trying to evade the MIT evidence with publicizing his case.
djr
not rated yet Feb 13, 2012
It's just you who refuses to understand what's hidden beneath the cold fusion." Not at all - if cold fusion is for real - show us the money - and I will be first in line to put an ecat outside my house. Rossi claims he will be selling them for $400 per kilowat - and with minimal fuel cost. I am waiting - I am first in line. It is you conspiracy theorists who don't understand science - a very simple principle - show us the money - I am waiting.