Scientists produce H2 for fuel cells using an inexpensive catalyst under real-world conditions

Aug 23, 2012

(Phys.org)—Scientists at the University of Cambridge have produced hydrogen, H2, a renewable energy source, from water using an inexpensive catalyst under industrially relevant conditions (using pH neutral water, surrounded by atmospheric oxygen, O2, and at room temperature).

Lead author of the research, Dr Erwin Reisner, an EPSRC research fellow and head of the Christian Doppler Laboratory at the University of Cambridge, said: "A H2 evolution catalyst which is active under elevated O2 levels is crucial if we are to develop an industrial process – a chemical reaction that separates the two elements which make up . A real-world device will be exposed to atmospheric O2 and also produce O2 in situ as a result of water splitting."

Although H2 cannot be used as a 'direct' substitute for gasoline or ethanol, it can be used as a fuel in combination with fuel cells, which are already available in cars and buses. H2 is currently produced from and it produces the CO2 as a by-product; it is therefore neither renewable nor clean. A green process such as sunlight-driven water splitting is therefore required to produce 'green and sustainable H2'.

One of the many problems that scientists face is finding an efficient and inexpensive catalyst that can function under real-world conditions: in water, under air and at room temperature. Currently, highly efficient catalysts such as the noble metal platinum are too expensive and cheaper alternatives are typically inefficient. Very little progress was made so far with homogeneous catalyst systems that work in water and atmospheric O2.

However, Cambridge researchers found that a simple catalyst containing cobalt, a relatively inexpensive and abundant metal, operates as an active catalyst in pH neutral water and under atmospheric O2.

Dr Reisner said: "Until now, no inexpensive molecular catalyst was known to evolve H2efficiently in water and under aerobic conditions. However, such conditions are essential for use in developing green hydrogen as a future energy source under industrially relevant conditions.

"Our research has shown that inexpensive materials such as cobalt are suitable to fulfil this challenging requirement. Of course, many hurdles such as the rather poor stability of the catalyst remain to be addressed, but our finding provides a first step to produce 'green hydrogen' under relevant conditions."

The results show that the catalyst works under air and the researchers are now working on a solar water splitting device, where a fuel H2 and the by-product O2 are produced simultaneously.

Fezile Lakadamyali and Masaru Kato, co-authors of the study, add: "We are excited about our results and we are optimistic that we will successfully assemble a sunlight-driven water splitting system soon."

Their research was published today, 23 August, online in the journal Angewandte Chemie International Edition.

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Sean_W
1 / 5 (3) Aug 23, 2012
The question is now: how likely is it that a more stable version can be developed? And again a story about producing hydrogen or biofuels/chemicals is authored with little or no mention of the uses outside the fuel markets. As the article mentioned, hydrogen is currently created using fossil fuels but is used for many things beyond fuel.
sstritt
3.2 / 5 (9) Aug 23, 2012
Scientists at the University of Cambridge have produced hydrogen, H2, a renewable energy source

Hydrogen is NOT an energy SOURCE any more than electricity is an energy source.
jakack
1.6 / 5 (7) Aug 23, 2012
H2 is currently produced from fossil fuels and it produces the greenhouse gas CO2 as a by-product; it is therefore neither renewable nor clean. A green process such as sunlight-driven water splitting is therefore required to produce 'green and sustainable H2'.


Just thought it was funny that in the first sentence it's admitted that dirty fossil fuels are needed to create Hydrogen. Then in the next sentence makes it seem like solar driven dissociation is pure as the driven snow! :-)

Makes me wonder how 'green' the ENTIRE processing of these catalysts are...Do they also take dirty fossil fuels to process?
Sonhouse
5 / 5 (2) Aug 23, 2012
If it is a true catalyst it would work way past the break even point of manufacturing vs lifespan. That is to say, the amount of fossil fuel it potentially uses in its manufacture will make the catalyst last a long time, perhaps years. If so, the amount of fossil fuel it takes, if any, is a minor consideration.

The main thing is whether this technology would beat out other solar driven technologies purporting to do the same job.

May the best technology win.
dschlink
1 / 5 (1) Aug 23, 2012
And then there's the distribution problem. H2 cannot be piped. It must be compressed or chilled and transported by trucks. All three processes are energy-intensive.
jakack
2.3 / 5 (3) Aug 23, 2012
May the best technology win.
Here, here!
Parsec
not rated yet Aug 23, 2012
And then there's the distribution problem. H2 cannot be piped. It must be compressed or chilled and transported by trucks. All three processes are energy-intensive.

Many assumptions here. Development of materials that absorb large quantities of H2 keep getting better. While compression and chilling are the currently best available technology, in a few years they will not be. They will always (probably) have to be transported by truck, but if the transport uses H2 fuel cell engines, that is also fossil fuel free.

Thanks to government and private capitol support of green energy programs, all of this technology is flourishing in so many directions its hard to keep up. Assumptions based on where we stand today is not a reasonable place to guess where we will be in a few years.
GSwift7
2.3 / 5 (9) Aug 23, 2012
In regard to transporting H2, if the catalytic dissociation process is simple enough, you don't transport the hydrogen, you transport the water.

If the dissociation process is REALLY good, you don't carry H2 in your car either. You simply carry water and make H2 on demand. Water is actually an extremely dense storage medium for hydrogen. That's kinda sci-fi stuff compared to where we are now, but who knows when someone might have a eureka moment.
ValeriaT
3 / 5 (4) Aug 23, 2012
In this article the tris(bipyridine) cobalt(II), compounds ligated to cyclic polyamines and cobaloximes has been used. Unfortunately, the cobalt forms only one half of this supramolecular device - the second one is formed with bipiridyl complexes of ruthenium, which are expensive as hell. In addition the organic chemicals involved make the whole system unstable due the photodegradation.
ValeriaT
3 / 5 (4) Aug 23, 2012
A more interesting approach is described here. Artero has used the reductive electrodeposition of cobalt dinitrate hexahydrate in a potassium phosphate buffer onto a fluorine-doped tin oxide electrode. This produces a nanoparticulate coating comprising a layer of metallic cobalt on the electrode, covered by a cobalt-oxo/hydroxo-phosphate layer on the outside. When the electrode is operated against a silver/silver chloride electrode in an electrolyte of aqueous cobalt dinitrate, hydrogen gas is produced at overpotentials as low as 50mV, which are far lower than those reported for other cobalt-based catalysts. When the same electrode is operated at a positive potential, typically 1.16V relative to the silver/silver chloride electrode, a stable anodic current density is achieved and oxygen evolution occurs. This is made possible by a change in the structure of the catalyst under negative and positive potentials.
ValeriaT
3 / 5 (2) Aug 23, 2012
Note that the later system is chemically very close to David Nocera's "artificial leaf". Being a Nocera, I wouldn't be very happy from the European patent application (EP-12352001), which is based on that work.
javjav
5 / 5 (1) Aug 23, 2012
Hydrogen is NOT an energy SOURCE any more than electricity is an energy source.

I totally agree with sstritt. Maybe Hydrogen has a great potential for making batteries, fuel cells, or as an energy storage / energy transport medium, but never as a primary energy source (at least in this planet). Why most journalists confuse both concepts again and again? it is not so complex to understand.
ekoos
3 / 5 (2) Aug 23, 2012
Although H2 cannot be used as a 'direct' substitute for gasoline or ethanol


This is not correct there are cars that use hydrogen as a fuel for internal combustion engines.
antialias_physorg
1 / 5 (1) Aug 24, 2012
Scientists at the University of Cambridge have produced hydrogen, H2, a renewable energy source

Hydrogen is NOT an energy SOURCE any more than electricity is an energy source.

H2 is an energy source. Burn it and you get energy out.

H2 is not a PRIMARY energy source. Subtle difference.
Just thought it was funny that in the first sentence it's admitted that dirty fossil fuels are needed to create Hydrogen.

Then you didn't read the article. There's a difference between 'current state of H2 production' and 'is needed fo producing H2'

Although H2 cannot be used as a 'direct' substitute for gasoline or ethanol

BMW had a direct conversion of one of their engines to combust H2 (The BMW Hydrogen 7). H2 COULD be used as a direct substitute for gas (though it wouldn't be very sensible since there are better ways to use it)
antialias_physorg
5 / 5 (2) Aug 24, 2012
H2 cannot be piped. It must be compressed or chilled and transported by trucks.

H2 (as part of "town gas") was piped in to feed gas lamps as early as 1812. By 1850 most towns had systems for their street lighting carrying the gas via pipes to the destination (and also to selected homes).
So I do think we'd be capable of rigging something up that works today.

Trucks are also used for gas/ethanol transport today (as is H2). It's not like these technologies aren't around or are freakishly expensive/inefficient.
Eikka
3 / 5 (2) Aug 24, 2012
Development of materials that absorb large quantities of H2 keep getting better.


Yes. They're called hydrocarbons.
packrat
1 / 5 (2) Aug 25, 2012
The fuel part of town gas was mostly carbon monoxide. The H2 content was only a small percentage of the whole in most of the various types. Town gas was also a low pressure system. Pure vaporized gasoline was also used the same way.

H2 could be used like that if used in a low pressure system as long as they added something to give it a smell like in propane as it burns with a colorless flame and has no smell. In that respect it's much more dangerous for the average homeowner to use.

H2 cannot affordably be pumped long distance at high pressure through systems like we do NG because of the embrittlement problems caused to the steel the pipes are made from. Yes, various alloys can be made to work with it but they are very expensive compared to normal materials used in fabricating pipes.

One question I have if anyone knows the answer. How do they separate the H2 and the oxygen in the output of this type of setup?
Eikka
not rated yet Aug 25, 2012
One question I have if anyone knows the answer. How do they separate the H2 and the oxygen in the output of this type of setup?


I would assume some sort of adsorption system.

The real issue is that the H2 concentration must be very low to prevent explosion hazard in air with the extra oxygen added, and that means it's more expensive to extract out of the mixture.
MIBO
not rated yet Aug 25, 2012
GSwift7 says
"If the dissociation process is REALLY good, you don't carry H2 in your car either. You simply carry water and make H2 on demand."

I think you lost the plot here. H2O requires a lot of energy to split, if the process is 100% efficient both in splitting and recombining you would get back exactly the amount of energy you put in.
But if you had the energy source to do this on demand then you would simply use that energy source to power the vehicle.
Solar splitting is perfect, but it cannot produce sufficient energy to run a vehicle even if the vehicle surface were 100% used for it, the idea is to use large area solar converters to produce the H2 during daylight, store that energy chemically as H2, and re-combine the H2 with oxygen to release the energy when it is needed.
And transporting the H2 is an issue, under pressure it requires heavy cylinders so is inefficient, and cannot be safely used in a vehicle.
using a metal "absorber" is safer but still relatively heavy.
LEVI506
1 / 5 (1) Aug 25, 2012
The Cyclone external combustion engine can easily use hydrogen as a direct fuel source. As a matter of fact the Cyclone engine can burn almost anything not only efficiently, but almost pollution free. Don't think it's real? Check with Raytheon. They are developing it for use with "Moden" Fuel in submersibles and it's under development for the army as an aux. 10 KW generator for stand down times on the M1 Abrams and the Bradley.
antialias_physorg
1 / 5 (1) Aug 26, 2012
H2 cannot affordably be pumped long distance at high pressure through systems like we do NG because of the embrittlement problems caused to the steel the pipes are made from

Then don't use steel pipes.
A single layer of graphene has already been shown to be enough to stop embrittlement. There are probably other low cost substances that can be used (the town gas lines were made of wood)

One question I have if anyone knows the answer. How do they separate the H2 and the oxygen in the output of this type of setup?

In a closed system the H2 will float to the top. If you have a steady production of H2 you cna continually syphon it off the top.
packrat
1 / 5 (2) Aug 26, 2012
Ap, Don't get into the hydrogen business as you would quickly end up getting people killed with those 2 ideas.
First of all, transfer piping is high psi. Plastic isn't going to work and stainless steel would cost far too much. Also those pipes must be welded together so graphene wouldn't work either. It would just be burnt off in the very spots it would caused the most problems!

H2 will not float to the top of a closed system in an H2-O2 mix in normal processes in any type of useful time frame. Those gases would have to be cooled to cryogenic temps and separated in a still setup or some type of osmosis system.

Maybe in a sealed insulated container the gases might separate out enough after a long time but there would still be the problem of how to keep from getting the o2 also. That would not be a use-able process except for maybe a small amount in a lab and even then it would be a toss up on whether you got pure H2 with NO O2 left in the mix.
SatanLover
1 / 5 (1) Aug 26, 2012
H2 cannot affordably be pumped long distance at high pressure through systems like we do NG because of the embrittlement problems caused to the steel the pipes are made from

Then don't use steel pipes.
A single layer of graphene has already been shown to be enough to stop embrittlement. There are probably other low cost substances that can be used (the town gas lines were made of wood)

One question I have if anyone knows the answer. How do they separate the H2 and the oxygen in the output of this type of setup?

In a closed system the H2 will float to the top. If you have a steady production of H2 you cna continually syphon it off the top.

Have you ever looked into a hydrogen storage company? Very expensive and it is the next challenge to overcome for an hydrogen "economy"
antialias_physorg
not rated yet Aug 26, 2012
First of all, transfer piping is high psi.

Since I'm not advocating piping H2 into homes I don't see much of a problem. Heating can be done electrically. Electricity would still be produced at central power plants: Alternative when available, from H2 when not (and the H2 being produced when wind, solar, hydro produces more energy than can be used)

Best use for hydrogen in cars would be (IMO) to have a small battery for the first and last miles. If you want to go longer trips fuel up with H2 at a filling station and dump the rest at a filling station near your destination.

This way you would never have H2 near people. (And we already do a lot of stuff with H2 - and there is a noted lack of constant catastrophic consequences Even in 1850 there were very few. So I think this fear of H2 is vastly overblown)

That would not be a use-able process except for maybe a small amount in a lab

The question was, as I understand it, adressed at the lab reported about.
Jitterbewegung
not rated yet Aug 27, 2012
What is the picture of?

H2 is a clear gas and becomes purple in the plasma state.

2H2O (heavy water) looks more like that picture.
MIBO
not rated yet Aug 27, 2012
presumably the picture of of the catalyst dissoled in water producing the gasses.
physpuppy
not rated yet Aug 27, 2012
@MIBO - maybe the catalyst. Looks a lot like anti freeze though :-)

@Jitterbewegung - heavy water D2O is clear at least in the visible spectra. I have a bottle of it right in front of me and I don't see any coloration at all.
rwinners
1 / 5 (1) Aug 27, 2012
"A green process such as sunlight-driven water splitting is therefore required to produce 'green and sustainable H2'."

Well, in the far future, sure. But for now, using relatively clean electricity to produce H2 will be fine.
Shootist
1 / 5 (2) Aug 28, 2012
Scientists at the University of Cambridge have produced hydrogen, H2, a renewable energy source

Hydrogen is NOT an energy SOURCE any more than electricity is an energy source.


Truly, there are no hydrogen mines.
ValeriaT
3 / 5 (2) Aug 28, 2012
@MIBO - maybe the catalyst. Looks a lot like anti freeze though
You're actually quite right - it's the Eosin (Na2EY) used as a redox indicator in this study. The antifreeze is colored with the same fluorescent dye. The molecule of eosin Y get excited by photons, transfer the excess electron into cobalt atom, and get reduced back by the redox couple H3O-Co. The dye therefore serves there as a primary absorbent of photon.
GSwift7
1 / 5 (1) Aug 29, 2012
One question I have if anyone knows the answer. How do they separate the H2 and the oxygen in the output of this type of setup?

In a closed system the H2 will float to the top. If you have a steady production of H2 you cna continually syphon it off the top


Depending on the process you use, different methods can be used to get only the hydrogen. Take a look at the following experiment you can do safely in your kitchen. You probably already have everything you need to try this:

http://www.energy...h2o.html

In a typical setup, you divide the top half of the water container. If you place the cathode and anode on opposite sides of the divider, then you'll get oxygen at the top of the cathode side, and hydrogen at the top of the anode side. That makes it easy to collect the hydrogen on that side of the divider.

btw, did you know that hydrogen is not water soluable?
GSwift7
1 / 5 (2) Aug 29, 2012
Hydrogen is NOT an energy SOURCE any more than electricity is an energy source.

Truly, there are no hydrogen mines.


If you want to get really philosophical, there's not really any such thing as an energy source. The Universe has a finite quantity of matter and energy, and the two are equivelant. You can't really create energy; you can only store it in some form. In that sense, hydrogen is just as much an energy source as any other method of storing energy. A rock sitting on top of a hill can be called a potential energy source if you want to be really technical. Hydrogen, once it is split from water, becomes an energy source just the same, though it's more correct to call it an energy storage medium. It's all symantics though. Anything with a local deficite in entropy 'can' be called an energy source, or you can argue that the big bang is the only energy source.
GSwift7
1 / 5 (1) Aug 29, 2012
Back on topic:

The article above doesn't say if their system gets around the platinum problem. I assume that they are still using electrical current in conjunction with the catalyst, which means they still need electrodes. As far as I know, platinum is the best choice, but it's prohibitively expensive to replace them after they get too much condensate on them.
packrat
1 / 5 (2) Aug 29, 2012
One question I have if anyone knows the answer. How do they separate the H2 and the oxygen in the output of this type of setup?

In a closed system the H2 will float to the top. If you have a steady production of H2 you cna continually syphon it off the top


Depending on the process you use, different methods can be used to get only the hydrogen. Take a look at the following experiment you can do safely in your kitchen. You probably already have everything you need to try this:

http://www.energy...h2o.html


I did that experiment 40 years ago. The problem I keep seeing in the pictures all these scientist keep showing is that the H2 and Oxygen is being made in the same container without separating the sides. It doesn't separate all that well in a closed container either unless the container is insulated and left to sit for a while. The only thing I can think of that would be reasonably efficient is cryogenic distillation for that setup
GSwift7
1 / 5 (1) Aug 29, 2012
I did that experiment 40 years ago. The problem I keep seeing in the pictures all these scientist keep showing is that the H2 and Oxygen is being made in the same container without separating the sides.


In an industrial setup, they would isolate the anode and cathode sides. They just don't bother in experiments.

Another problem with many catalytic solutions like the one above, is what kinds of waste byproducts are produced. Dealing with large quantities of amonia, for example, can be a problem. The above story isn't specific about the byproducts you would get using regular tap water, river water or salt water, though I'm sure the researchers have that information. In the do-it-yourself experiment I linked to, the table salt produces chlorine gas, which would be undesireable in industrial scale production. The byproducts are probably the biggest factor differentiating various catalysts and choices of electrodes.
MalcS
not rated yet Oct 18, 2012
Feed the hydrogen and oxygen produced straight into a fuel cell or even a gas turbine to generate electricity, or use the hydrogen to convert CO2 into methane, ethane or higher hydrocarbons.