A nanosized hydrogen generator

September 20, 2014 by Justin H.s. Breaux
Argonne researchers produce trace amounts of hydrogen with visible light by merging light-collecting proteins from a single-celled organism with a graphene platform. Both graphene and protein absorb the light and re-direct electrons towards the titanium dioxide. Electrons interact with protons at the site of the platinum nanoparticles to produce hydrogen. Credit: John Lambert.

(Phys.org) —Researchers at the US Department of Energy's (DOE) Argonne National Laboratory have created a small scale "hydrogen generator" that uses light and a two-dimensional graphene platform to boost production of the hard-to-make element.

The research also unveiled a previously unknown property of graphene. The two-dimensional chain of not only gives and receives , but can also transfer them into another substance.

Hydrogen is virtually everywhere on the planet, but the element is typically bonded with other elements and must be separated from oxygen in H2O to produce free hydrogen. The commercial separation process uses natural gas to react with superheated steam to strip away hydrogen atoms producing , but also carbon dioxide —a greenhouse gas byproduct which escapes into the atmosphere.

Argonne's early-stage generator, composed of many tiny assemblies, is proof that hydrogen can be produced without burning fossil fuels. The scale is small, a little smaller than the diameter of spider silk. Scaling this research up in the future may mean that you could replace the gas in your cars and generators with hydrogen—a greener option, because burning hydrogen fuel emits only water vapor.

"Many researchers are looking to inorganic materials for new sources of energy," said Elena Rozhkova, chemist at Argonne's Center for Nanoscale Materials, a DOE Office of Science (Office of Basic Energy Sciences) User Facility. "Our goal is to learn from the natural world and use its materials as building blocks for innovation."

For Rozhkova, this particular building block is inspired by the function of an ancient protein known to turn light into energy. Researchers have long known that some single-celled organisms use a protein called bacteriorhodopsin (bR) to absorb sunlight and pump protons through a membrane, creating a form of chemical energy. They also know that water can be split into oxygen and hydrogen by combining these proteins with titanium dioxide and platinum and then exposing them to ultraviolet light.

There is just one downside: titanium dioxide only reacts in the presence of ultraviolet light, which makes up a mere four percent of the total solar spectrum. If the researchers wanted to power their generators with sunlight, they'd need to improve on that.

In order to produce greater amounts of hydrogen using , the researchers looked for a new material. The new material would need enough surface area to move electrons across quickly and evenly and boost the overall electron transfer efficiency. The researchers also needed a platform on which biological components, like bR, could survive and connect with the titanium dioxide catalyst: in short, a material like graphene.

Graphene is a super strong, super light, near totally transparent sheet of carbon atoms and one of the best conductors of electricity ever discovered. Graphene owes its amazing properties to being two-dimensional.

"Graphene not only has all these amazing properties, but it is also ultra-thin and biologically inert," said Rozhkova. "Its very presence allowed the other components to self-assemble around it, which totally changes how the electrons move throughout our system."

Rozhkova's mini-hydrogen generator works like this: both the bR protein and the graphene platform absorb visible light. Electrons from this reaction are transmitted to the titanium dioxide on which these two materials are anchored, making the titanium dioxide sensitive to visible light.

Simultaneously, light from the green end of the solar spectrum triggers the bR protein to begin pumping protons along its membrane. These protons make their way to the platinum nanoparticles which sit on top of the . Hydrogen is produced by the interaction of the protons and electrons as they converge on the platinum.

Examinations using a technique called Electron Paramagnetic Resonance (EPR) and time-resolved spectroscopy at the Center for Nanoscale Materials verified the movements of the electrons within the system, while electrochemical studies confirmed the protons were transferred. Tests also revealed a new quirk of graphene behavior.

"The majority of the research out there states that graphene principally conducts and accepts electrons," said Argonne postdoctoral researcher Peng Wang. "Our exploration using EPR allowed us to prove, experimentally, that graphene also injects electrons into other materials."

Rozhkova's generator proves that nanotechnology, merged with biology, can create new sources of clean energy. Her team's discovery may provide future consumers a biologically-inspired alternative to gasoline.

"These are the types of discoveries we can make at Argonne," said Rozhkova. "Working in the basic energy sciences, we were able to demonstrate an energy-rich biologically-inspired alternative to gas."

This research, "Photoinduced Electron Transfer pathways in Hydrogen-Evolving Reduced Graphene Oxide-Boosted Hybrid Nano-Bio Catalyst," appeared in the July 7 issue of ACS Nano.

Explore further: Microorganisms found in salt flats could offer new path to green hydrogen fuel

More information: ACS Nano, pubs.acs.org/doi/abs/10.1021/nn502011p

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5 / 5 (5) Sep 20, 2014
Anything that has the possibility of turning the Middle East back to goat herders and kill off Big Oil.
not rated yet Sep 20, 2014
Who do you think is going to buy up all the patents associated with this new development? .......You got it!
not rated yet Sep 20, 2014
A good start but of course to scale it up for practical use the obvious question is "how much titanium dioxide is there in the world?". It might be possible to avoid a titanium bottleneck by developing the process to use a more common compound as catalyst/substrate.
not rated yet Sep 20, 2014
Hydrogen Generators how cool is that?
2.6 / 5 (5) Sep 20, 2014
Petroleum is dying and coal is dead.
1 / 5 (2) Sep 20, 2014
"because burning hydrogen fuel emits only water vapor."

Ahem. Only in the presence of pure O2. You still could get trace amounts of other compounds from combustion with ambient air, and high NOx emissions.

"There are four basic issues regarding hydrogen-fueled engines and vehicles: engine backfire and susceptibility of hydrogen to surface ignition, somewhat reduced engine power, high nitric oxide (NOx) emissions, and the problem of on-board storage of the fuel and safety. Although partial solutions have been found to most of these problems, there still is no general consensus of the best method to finally resolve all of these issues."

3 / 5 (6) Sep 20, 2014
Skepticus_Rex, why would you assume this fuel would be used in an internal combustion engine?

More than likely it would be used for fuel cell operations.
1 / 5 (2) Sep 20, 2014
Did anyone else notice that the sun in the image below the title is actually an egg yolk? How that white reflective glint on its surface escaped scrutiny by the graphic artists is unforgivable.
2 / 5 (4) Sep 20, 2014
baudrunner, why would you put a comment like that to a serious article?
2 / 5 (4) Sep 21, 2014
Although this article is of some interest, I am mindful that nature 'chose' carbon as the primary energy carrier in that it produces high density energy compounds that are liquid & solid.

It was reported on an end to end thermodynamic analysis that even if H2 were free, it would be too expensive to use. That was years ago, would love to find it again ?

Nature seems to have come to similar conclusion, also waste products from those processes are 'exhausted ash' as CO2 & H2O but not H2. Its also known H2 is a powerful GHG.

World already has significant utility liquid fuel infrastructure, wouldn't it make commercial & likely thermodynamic sense to only use H2 (if free eg waste) as intermediary (at point of origin) to generate high density liquid fuel which feeds immediately into our existing systems.

Terrestrially H2 has too many combinatorial problems & any system which converts electricity to H2 appears a huge waste, as there will always be better uses for that electricity !
Sep 21, 2014
This comment has been removed by a moderator.
3 / 5 (2) Sep 21, 2014
Petroleum is dying and coal is dead.

The way rightwingers carry on, you'd be forgiven for thinking they are the latest and greatest energy source.
1 / 5 (3) Sep 21, 2014
Goika, Hydrogen will be used, because in many situations it makes sense, even if you are unaware of them. We will employ all energy sources, as we did in California in the 1980's.

Now those technologies we used then are available to all of you. And you will all use them, eventually.
1 / 5 (1) Sep 21, 2014
Hydrogen is a gas, it burns readily and if used by the general public you will have explosions and fires, a lot of both. Natural gas used by the general public is not detechable by the nose so they add Hydrogen sulfide to the gas in small quantities so you smell a leak. The pipelines to distribute Hydrogen do not exist and would need to be built at great cost along with all the other support hardware. Since Hydrogen is a pretty small molecule, you are going to get more leaks than with natural gas so that support structure will have more leaks including your line into your house. Aside from those not so minor problems this research is pretty lame, It simply uses a protein, a support structure and sunlight to generate a very tiny amount of hydrogen at a very low efficiency and I suspect a very short lifetime as a protein is food to a lot of bacteria.. Needs a long way to go to get to useful size and output.
Sep 21, 2014
This comment has been removed by a moderator.
1 / 5 (3) Sep 22, 2014
gkam stated
We will employ all energy sources, as we did in California in the 1980's.
... And you will all use them, eventually.
My understanding is the experience of California re H2 was the same as ours in Perth, Western Australia 2004-7.ie. Massive waste of money/emissions. Link to the final report:-
(Note weight only 44Kg/bus !)

Can you link us to California's H2 bus trials, I think there were several, top three ?

I would also like to clarify your definitive perception of your firm expectation gkram
Hydrogen will be used, because in many situations it makes sense, even if you are unaware of them.
Most intriguing are you referring to hydrogen as a fuel & from renewable sources ?

Please indicate the top three "situations it makes sense" ?

Have any of these:-
a. Had an 'end to end' thermodynamic/cost analysis published ?
b. In trial or a production process ?
c. CO2 emissions ?
1 / 5 (1) Sep 27, 2014
Skepticus_Rex, why would you assume this fuel would be used in an internal combustion engine?

More than likely it would be used for fuel cell operations.

The technology just isn't there for large scale deployment of H2 and current pure-H2 fuel cell stacks are extremely expensive. Most fuel cell arrangements use a mixture and/or use a process to separate H2 from natural gas before introducing it to a fuel cell. Such mixtures also produce smaller amounts of NOx but it still isn't zero, as well as reduced carbon emissions. Certain processes that introduce the H2 into the fuel cell also run the risk of introducing contaminants. And, then there is the ozone produced by the electric motors in such vehicles. Add to that the emissions from generating the H2 in the first place. At current levels of technology, there is no such thing as a truly zero emission vehicle. It would be nice if there were but there isn't. Feel free to one-rank accordingly. :-)

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