Hydrogen fuel tech gets boost from low-cost, efficient catalyst

May 02, 2011
A team of researchers have engineered a cheap, abundant alternative to the expensive catalyst platinum and coupled it with a light-absorbing electrode to make hydrogen fuel from sunlight and water. The discovery was published in Nature Materials by theorist Jens Nørskov of the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University and a team of colleagues led by Ib Chorkendorff and Søren Dahl at the Technical University of Denmark. The team optimized a photo-electrochemical water splitting device by designing light absorbers made of silicon arranged in closely packed pillars, imaged above using a scanning electron microscope. After dotting the pillars with tiny clusters of the new catalyst and exposing the pillars to light, researchers watched as hydrogen gas bubbled up -- as quickly as if they'd used costly platinum. Credit: Image courtesy of Christian D. Damsgaard, Thomas Pedersen and Ole Hansen, Technical University of Denmark.

Scientists have engineered a cheap, abundant alternative to the expensive platinum catalyst and coupled it with a light-absorbing electrode to make hydrogen fuel from sunlight and water.

The discovery is an important development in the worldwide effort to mimic the way plants make fuel from sunlight, a key step in creating a economy. It was reported last week in by theorist Jens Norskov of the Department of Energy's SLAC National Accelerator Laboratory and Stanford University and a team of colleagues led by Ib Chorkendorff and Soren Dahl at the Technical University of Denmark (DTU).

is an energy dense and clean fuel, which upon combustion releases only water. Today, most hydrogen is produced from natural gas which results in large CO2-emissions. An alternative, clean method is to make from sunlight and water. The process is called photo-electrochemical, or PEC, water splitting. When sun hits the PEC cell, the solar energy is absorbed and used for splitting into its components, hydrogen and oxygen.

Progress has so far been limited in part by a lack of cheap catalysts that can speed up the generation of hydrogen and oxygen. A vital part of the American-Danish effort was combining theory and advanced computation with synthesis and testing to accelerate the process of identifying new catalysts. This is a new development in a field that has historically relied on trial and error. "If we can find new ways of rationally designing catalysts, we can speed up the development of new catalytic materials enormously," Nørskov said.

The team first tackled the hydrogen half of the problem. The DTU researchers created a device to harvest the energy from part of the solar spectrum and used it to power the conversion of single hydrogen ions into . However, the process requires a to facilitate the reaction. Platinum is already known as an efficient catalyst, but platinum is too rare and too expensive for widespread use. So the collaborators turned to nature for inspiration.

They investigated hydrogen producing enzymes—natural catalysts—from certain organisms, using a theoretical approach Nørskov's group has been developing to describe catalyst behavior. "We did the calculations," Nørskov explained, "and found out why these enzymes work as well as they do." These studies led them to related compounds, which eventually took them to molybdenum sulfide. "Molybdenum is an inexpensive solution" for catalyzing hydrogen production, Chorkendorff said.

The team also optimized parts of the device, introducing a "chemical solar cell" designed to capture as much solar energy as possible. The experimental researchers at DTU designed light absorbers that consist of silicon arranged in closely packed pillars, and dotted the pillars with tiny clusters of the molybdenum sulfide. When they exposed the pillars to light, hydrogen gas bubbled up—as quickly as if they'd used costly platinum.

The hydrogen gas-generating device is only half of a full photo-electrochemical cell. The other half of the PEC would generate oxygen gas from the water; though hydrogen gas is the goal, without the simultaneous generation of oxygen, the whole PEC cell shuts down. Many groups—including Chorkendorff, Dahl and Nørskov and their colleagues—are working on finding catalysts and sunlight absorbers to do this well. "This is the most difficult half of the problem, and we are attacking this in the same way as we attacked the hydrogen side," Dahl said.

Nørskov looks forward to solving that problem as well. "A sustainable energy choice that no one can afford is not sustainable at all," he said. "I hope this approach will enable us to choose a truly sustainable fuel."

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holoman
1 / 5 (11) May 02, 2011
Oh great !

First we convert food supply into fuel.

And now they want to convert another important life
sustaining resource into fuel.

Now if they would have invented using seawater would
have hooray ! but this concept uses fresh water only.

This is bad for the world.
antialias
5 / 5 (7) May 02, 2011
This is bad for the world.

Why? When you use the hydrogen you get the clean water back. Where's the problem?
kaasinees
0.4 / 5 (33) May 02, 2011
using fuel to create fuel. what a moronic idea.
dschoutens
5 / 5 (7) May 02, 2011
using fuel to create fuel. what a moronic idea.

Ultimately, what they are really doing is storing collected SOLAR energy in the form of Hydrogen gas / fuel... Not too moronic if you think about it, especially if the process they use to store that energy is relatively inexpensive.
pauljpease
5 / 5 (9) May 02, 2011
Holoman and kaasinees are why we don't have alternative energy already, as they represent the vast majority of society that can't understand even simple concepts. By Holoman's logic, plants too are bad because they use fresh water. And I can't even begin to guess what kaasinees is referring to, there is no mention of "using fuel to create fuel" in the article, they are using SUNLIGHT to create fuel.

While it might be shocking to some physorg readers, as a high school math and science teacher I am not surprised by this. The "normal" high school student can't grasp basic concepts or follow a logical argument. And things don't seem to improve much in this respect after they finish school, as they become absorbed in earning a living. Perhaps Holoman and kaasinees have advanced degrees, which speaks not to their ability but to the lowered expectations of our education system...
kaasinees
0.4 / 5 (28) May 02, 2011
There is nothing "green" about any fuel based technology.
If we ignore that part for now and concentrate on hydrogen as a fuel, there are still major problems from making this economically viable.

- Water is the #1 green house gas of the planet. The key to a sustainable future is to generate energy without messing up ecosystems, meaning
- Transportation is expensive, it requires special containers that are expensive. And if we want to transport lots of hydrogen in a small area it will become even more expensive. Plus the energy costs of liquefying hydrogen.
- Plus the low ratio of weight/energy will make transportation less cost effective. In the end we wont get more energy out of hydrogen then got from the sun.
- Hydrogen is highly corrosive to metal and breaks metals over time. (more expensive)

So paul, the one without real arguments is you, i geuss you should go back to a proper school and take some real lessons from people who know what they are talking about.
(char limit)
bbdk
5 / 5 (5) May 02, 2011
@kaasinees
Did you read the article? It's artificial photosynthesis of a sorts. The raw materials going in are water and photons. The products are hydrogen and oxygen, which are then combusted to produce energy we can tap into. The waste product is H2O... Hmm, let's stuff that back into the powerplant to produce some more power.
Why should we let the vapor out into the atmosphere? That would be counterproductive.
Your points about costs are all moot. It costs nothing. The plant produce the energy needed. That's the whole point really.
Sure, we could put the hydrogen into tanks and transport them all over the place, but why on earth would we do that, when we already have a functional electricity grid and exiting new nanoengineered materials on the way that will essentially put batterypower at the forefront of personal energy consumption.
Corrosive to metal? Use ceramics or composites. problem solved.
Timothy_Wilson
5 / 5 (4) May 02, 2011
If I have a bank of these on my roof, that cracks a given number of litres of water, then at night, a fuel cell 'gives back' that energy to run my house, along with the water. Then the next day the cycle repeats.

So, I barely 'use' any water day to day, But I can't imagine its more than a few grams a day lost anywhere in the system. If that. Even if it DID consume more than that, I can get that from heating a few grams of 'gray water' (with a parabolic dish) from my house and making steam, which I could pump into the water tank.

No water released.

No transportation required, its my house.

Hydrogen doesn't corrode metals in air. There is embrittlement, but thats at higher temperatures. Even if hydrogen was 'corrosive to metals', then I simply wouldn't use metals in containment. How was that even an argument?

All this only makes sense if its efficient to do this conversion. The fuel cell efficiency also has to be factored in.
kaasinees
0.2 / 5 (26) May 02, 2011
Did you read the article? It's artificial photosynthesis of a sorts.

Why not directly convert photons to electrons? Much more efficient. The technology just hasn't reached the market yet for various reason.
The raw materials going in are water and photons.

Which makes the photons and water the fuel to create some other type of fuel. The catalyst will require fresh water and will still corrode and be polluted decreasing efficiency of the materials rapidly. Will require either expensive water cleaning that costs alot of energy or regular cleaning/replacement .
The products are hydrogen and oxygen, which are then combusted to produce energy we can tap into.

Which requires expensive containment which maintenance will be expensive. Even if used directly in a plant.
The waste product is H2O... Hmm, let's stuff that back into the powerplant to produce some more power.

Where is the pressure going to go? It has togo somewhere. You can't simply "trap" the products
bbdk
5 / 5 (3) May 02, 2011
Oh, it's more efficient with solar cells? If you would be so kind as to find the numbers, I would be very interested in seeing the efficiency comparisons between photovoltaic cells and this technology then. I'll reserve judgement until the required O catalyst has been added to the mix. I do know that we're at about 40% efficiency with photovoltaic cells now and that the expectations of getting much higher than that are very low.
Water isn't 'the fuel'. Water is the reactant, H and O are the products, which then becomes the reactants that produce the energy in the usual combustion fashion that all physics students have seen in some classroom/lab.
Where did you find out that the molybdenum sulfide catalyst gets coked or inhibited in the process? Could you provide a link to that information please. It would be interesting to read the findings on that.
There's quite a big difference between a catalyst in this scenario and a catalyst in say a car. A catalyst doesn't HAVE to become coked.
bbdk
5 / 5 (2) May 02, 2011
You can't 'trap' the products... So, what you're saying is, that you don't believe there's such a thing as NASA, sending stuff into space. Atlas, Saturn and the shuttles used liquid oxygen and liquid hydrogen for propellant.
bbdk
5 / 5 (1) May 02, 2011
...Or, you can 'combust' the reactants with a catalyst, like in a fuel cell.
kaasinees
0.2 / 5 (24) May 02, 2011
You can't 'trap' the products... So, what you're saying is, that you don't believe there's such a thing as NASA, sending stuff into space. Atlas, Saturn and the shuttles used liquid oxygen and liquid hydrogen for propellant.


But they dont combust anything ;)
antialias
5 / 5 (4) May 02, 2011
Why not directly convert photons to electrons?

Because hydrogen has a vast advantage over electrons in an energy grid: it can be stored.

Batteries are very expensive as a means of energy storage. Storing (and transporting) hydrogen is comparatively easy.

For some uses batteries are better, for some hydrogen is better. Using only one approach of the two isn't sensible.
bbdk
5 / 5 (2) May 02, 2011
1. Not really the point :)
It was one example out of probably thousands of places where we utilize 'trapped' (let's call it contained from now on) hydrogen and oxygen.
2. Of course they combust. When hydrogen is oxidized, it's combustion. That yellowish/orangey hot stuff that spurts out of the shuttle ET.. .That's hydrogen being oxidized... Or combusted if you will.
Sanescience
5 / 5 (2) May 02, 2011
Quick weigh in:

Hydrogen is a *HORRIBLE* transporter of energy.

Why? Because it's presence on the surface of the earth is *very* unnatural. It's physical properties require very expensive engineering to store and transport it. Nature has shown the way how to make hydrogen useful, stick it onto some carbon atoms and wallah, a hydrocarbon that is easy to transport and store.

As long as those carbon atoms come from the air (above the ground), your not adding to concentrations of CO2, otherwise know as "carbon neutral".

If there is ever a market for photovoltaic energy that is not used directly on the grid, it will probably be best used in the direct synthesis of methane or possibly larger molecules.

For example:

http://www.physor...765.html
PinkElephant
1 / 5 (1) May 02, 2011
and wallah
That would be "voila". Otherwise, you're quite right.
kaasinees
0.1 / 5 (23) May 03, 2011
As long as those carbon atoms come from the air (above the ground), your not adding to concentrations of CO2, otherwise know as "carbon neutral".


And when you combust the hydrocarbon, you are still releasing an extra H. And where will you put the O?

In the end all you are doing is moving the energy requirement. You are not actually producing any energy. Actually you are wasting the energy you got from the sunlight.

In the end you are still releasing gasses in the atmosphere that you should not.
bbdk
not rated yet May 03, 2011
@ kassinees
Look, as I see it you either
a) Seem to have little knowledge of chemistry and physics and should maybe obtain a little basic knowledge in those areas, instead of making up stuff that's easily refutable?
or
b) are just trolling.
Either way, your posts on this subject exhibits less than rudimentary knowledge on the particular areas of physics and chemistry the article is dealing with.
For the record:
2H2O + photon + catalyst to 4H + O2
CO2 + 4H + enzyme to CH4 + O2
CH4 + 2O2 to 2H2O + CO2 + heat
wwqq
not rated yet May 07, 2011
And now they want to convert another important life
sustaining resource into fuel.


It takes 1000 gallons to grow the wheat for 2 pounds of bread.

1000 gallons of water contains enough hydrogen to store as much energy as is contained in 10 barrels of oil. What an average western European uses in an entire year(including industry associated with maintaining their lifestyle and petrochemicals they use).

Of all the arguments you could have made against hydrogen you went straight for the hopelessly innumerate one.
rgharakh
not rated yet May 07, 2011
From what I gather the point of this is not to provide a single source of power for everything but to provide another notch in the way we use renewable energy. Obviously the most efficient way would be to turn photons directly into current but considering battery technology isn't really ready to store all this power when the suns down, the most effective storage method becomes hydrogen (there is other methods of solar energy storage but keeping the energy in one form is the most efficient.) Since we largely use gas/fluids as energy storage right now, hydrogen storage would not be such a radical departure on an applications basis.
malapropism
not rated yet May 08, 2011
Don't give even a 1 rank to these trolling low-life supposed traders - just "report abuse" on them to the Physorg guys; they do seem to get onto removing the posts pretty quickly. The more real readers report them, the sooner their posts will be removed from all articles they hit.
lengould100
not rated yet May 09, 2011
Can't decide which is more depressing: That people like kaasinees try to set themselves up as knowledgeable on technology such as this, or that there seems to be an increasing portion of our society which simply automatically post negative on any new development, regardless of its efficacy. Knee-jerk takes on a whole new relevance.
kaasinees
0 / 5 (21) May 16, 2011
Can't decide which is more depressing: That people like kaasinees try to set themselves up as knowledgeable on technology such as this, or that there seems to be an increasing portion of our society which simply automatically post negative on any new development, regardless of its efficacy. Knee-jerk takes on a whole new relevance.

And you know who i am? You do not.
Hydrogen will only postpone the problems from gas to hydrogen, but for a longer period.
I could name a dozen of problems which will make hydrogen just worthless and a waste of energy.
antialias
not rated yet May 17, 2011
So do.

Hydrogen is an infinitely recyclable energy STORAGE while gas is a primary energy carrier which cannot recycle and puts out all kinds of pollutants.

And when you combust the hydrocarbon, you are still releasing an extra H. And where will you put the O?

The same place it is put nowadays when we combust hydrocarbons (oil and gas): it forms H2O.

Hydrogen 'postpones' nothing. It doesn't even play in the same ballpark. Hydrogen is a 'battery'-technology for an infinitely sustainable energy cycle on earth, while gas is just a problem.

Methane from solar and airborne CO2 is probably not such a good idea since we shift CO2 concentrations from areas where the power is generated to areas where the power is used. And methane doesn't burn 100% clean. You always get some NOx and other nasties.