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A leaf that could power the future

Silicon strip developed at MIT might be key to inexpensive fuel cells

By Erin Ailworth
Globe Staff / September 30, 2011

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The thumb-size black strip looks like a thin magnet. But in reality, it is an artificial leaf, made of silicon and capable of using sunlight to split water into hydrogen and oxygen that can be fed into fuel cells to make power.

“You drop it in a glass of water and you walk outside and hold it in the sun, and you’ll start to see bubbles of hydrogen and oxygen,’’ explained Daniel Nocera, an MIT professor who led the team that invented the device.

The next step, he said, is to make the technology work on a large scale to produce enough hydrogen and oxygen for a fuel cell to power a car or home.

The leaf, which Nocera has worked on for about three years, has the potential to solve one of the most pressing challenges facing solar power: how to store energy produced by the sun so it can be used on cloudy day.

Instead of a battery, that energy could be stored as oxygen and hydrogen gases, then recombined in fuel cells, which generate electricity from the chemical reaction.

Sun Catalytix Corp., the Cambridge company founded by Nocera to commercialize the technologies coming out of his lab at the Massachusetts Institute of Technology - wants to experiment with the leaf to make it more efficient, perhaps mimicking algae, which could be spread across large surfaces of water to produce hydrogen and oxygen in volume.

Executives and researchers at Sun Catalytix say Nocera’s leaf holds particular promise because it is made from low-cost, abundant materials, including silicon, cobalt, and nickel.

That could mean that, once commercialized, the leaf’s technology will be an inexpensive way to generate energy from nonpolluting sources.

“That’s something we’re still working on,’’ said chief executive Michael P. Decelle. “It takes a lot of engineering to turn a scientific achievement into a marketable product.’’

Sun Catalytix’s work is backed by venture capital firms, including Polaris Venture Partners of Waltham. Sun Catalytix raised $9.5 million in a funding round last year, and also has a contract for over $4 million in federal funding from the Department of Energy.

At Polaris, general partner Amir Nashat, who used to head Sun Catalytix, said his firm is watching how the artificial leaf develops.

“It [potentially] provides an avenue for giving everybody energy anywhere,’’ Nashat said. “If we can make it better, make it cheaper, make it more efficient [then] it could really change the way we think about where our fuel comes from.’’

Nocera, along with researchers at the MIT and Sun Catalytix, started working on the leaf in 2008 after inventing a cobalt and phosphate compound that acts as a catalyst to speed the transformation of water into its separate elements.

That compound now coats one side of the artificial leaf, drawing oxygen from the water; a nickel-based alloy coats the other side, releasing hydrogen.

“This is a problem that the scientific community has been working on for a very long time,’’ said Steven Y. Reece, a Sun Catalytix research scientist who helped develop the leaf.

Nocera, the Henry Dreyfus Professor of Energy and a professor of chemistry at MIT, said he likes the invention for its simplicity. Unlike other attempts to create a device to split water into its components, the artificial leaf doesn’t use corrosive solutions, he said, nor does it need a connection to an outside electrical current.

“I don’t have to have anything wired up, I don’t have to plug it into anything,’’ he said. “That‘s what leaves do: They take sunlight and they make a wireless current - like what is happening here.’’

Erin Ailworth can be reached at eailworth@globe.com. Follow her on Twitter @ailworth.