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Self-healing “artificial leaf” produces energy from dirty water

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April 10, 2013

The 'artificial leaf' created by Daniel G. Nocera, Ph.D. and his team now has self-healing...

The 'artificial leaf' created by Daniel G. Nocera, Ph.D. and his team now has self-healing capabilities (Photo: Dominick Reuter)

Back in 2011, scientists reported the creation of the “world’s first practical artificial leaf” that mimics the ability of real leaves to produce energy from sunlight and water. Touted as a potentially inexpensive source of electricity for those in developing countries and remote areas, the leaf’s creators have now given it a capability that would be especially beneficial in such environments – the ability to self heal and therefore produce energy from dirty water.

While the leaf mimics a real leaf’s ability to produce energy from sunlight and water, it doesn’t mimic the method real leaves rely on, namely photosynthesis. Instead, as described by Daniel G. Nocera, Ph.D. who led the research team, the artificial leaf is actually a simple wafer of silicon coated in a catalyst that, when dropped into a jar of water and exposed to sunlight, breaks down water into its hydrogen and oxygen components. These gases can be collected as they bubble up through the water to be used for fuel to produce electricity in fuel cells.

Because bacteria can build up on the leaf’s surface and stop the energy production process, previous versions of the device required pure water. Now Nocera’s team has found that some of the catalysts developed for the artificial leaf actually heal themselves, meaning the process can work with dirty water.

“Self-healing enables the artificial leaf to run on the impure, bacteria-contaminated water found in nature,” Nocera said. “We figured out a way to tweak the conditions so that part of the catalyst falls apart, denying bacteria the smooth surface needed to form a biofilm. Then the catalyst can heal and re-assemble.”

Where similar devices are expensive to manufacture due to the use of rare and expensive metals and complex wiring, Nocera’s artificial leaf uses cheaper materials and a simple “buried junction” design that he says would make it cheaper to mass produce. Additionally, less than one liter (0.25 gal) of water is enough to produce around 100 watts of electricity 24 hours a day. And while it isn’t necessarily the most efficient form of electricity generation, Nocera likens the approach to “fast-food energy.”

“We’re interested in making lots of inexpensive units that may not be the most efficient, but that get the job done. It’s kind of like going from huge mainframe computers to a personal laptop. This is personalized energy.

“A lot of people are designing complicated, expensive energy-producing devices, and it is difficult to see them being adopted on a large scale,” he added. “Ours is simple, less expensive, and it works.”

Nocera believes the artificial leaf is likely to find its first use in individual homes in areas that lack traditional electric production and distribution systems. As well as being cheaper than solar panels, because the artificial leaf doesn’t directly generate electricity, but produces hydrogen and oxygen that can be stored, the electricity could be generated for use at night.

The research team hopes to integrate the artificial leaf with technology for converting the hydrogen into a liquid fuel to power everything from traditional portable electric generators to cars.

Nocera described the artificial leaf at the 245th National Meeting & Exposition of the American Chemical Society that is currently being held in New Orleans.

Source: American Chemical Society

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag.   All articles by Darren Quick
6 Comments

I have some trouble with the content of this article:

How can it work 24 hours a day if the reaction requires sunlight?

No measure of the efficiency of the conversion is provided, nor the efficiency of the resulting hydrogen reaction to produce usable energy.

The 100W continuously from a litre of water is also a junk number. If I recall, direct sunlight provides about 1000W per square meter.

j-stroy
10th April, 2013 @ 07:44 am PDT

I have read with most interest your previous articles about the artificial leaf that Dr. Nocera developed while in MIT.

But, if I count the number of previous articles read, they must be around 7 or 8. I'm still to read about a product that derived from this research, or a developing country that has benefited from it.

Don't you have anything else to write about? I'm counting on your website to read about advances on technology, not about the same old invention over and over again, that seem more as a paid advertisement than research-news reporting.

When the elites in power of the world allow the new energy technologies to see the light of day, THAT will be news. But, for the time being, this is yet to happen, so do not annoy us with great technology that would be of inmense value to humankind, but is always ten years away.

Hopefully, the advances on many "un-controlled" fronts on the LENR technology would render it un-stoppable, and would become a reality long before the "artificial leaf" with its "controlled" environment.

Hurrah! for Dr. Nocera being selected as one of the one-hundred most influential pesons in the world. But this was on "2009", four years ago.

Its time to put his technology to work.

javierelizondo
10th April, 2013 @ 09:26 am PDT

it produces hydrogen which will be used to power what ?

how inexpensive ?

Gavin Roe
10th April, 2013 @ 12:56 pm PDT

j-stroy - "How can it work 24 hours a day if the reaction requires sunlight?"

Article - "These gases can be collected as they bubble up through the water to be used for fuel to produce electricity in fuel cells." "... but produces hydrogen and oxygen that can be stored, the electricity could be generated for use at night."

What it means is that the electricity generation in fuel cells can run 24/7, not the photosynthesis hydrolysis reaction.

"No measure of the efficiency of the conversion is provided, nor the efficiency of the resulting hydrogen reaction to produce usable energy."

As this technology uses relatively cheap materials, efficiency won't be that impressive. I don't know if you expected otherwise, but efficiency won't be critical looking at its application. It's interesting if it can generate electricity cheaper than say PV and is especially interesting given its continued use during night.

Photosynthesis in plants is not efficient to begin with. Fuel cells typically run at efficiencies of 50-60%.

"The 100W continuously from a litre of water is also a junk number. If I recall, direct sunlight provides about 1000W per square meter."

How is this not possible? Imagine one or a few square meters of this leaf material and a litre of water spread on top of it.

Fretting Freddy the Ferret pressing the Fret
11th April, 2013 @ 12:56 pm PDT

The article doesn't say that electricity generation can run for 24 hours a day. It merely states that enough energy is generated by a litre of water to run 100W for 24 hours. (I guess you could infer that around 15 litres could generate enough energy to run lights/appliances in an average house, per day).

I think its a great idea, but it's a pity that there is no evidence of its use anywhere in the world. It's quite possible that the technology used to achieve this is too expensive for developing (and maybe even developed) countries.

Shanti
13th April, 2013 @ 03:38 am PDT

can it use sea water, i mean saline water

Vruksho Rakshati Rakshitaha
13th April, 2013 @ 12:06 pm PDT
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