Scientists announced they have achieved one of the “Holy Grails of science” by creating the world’s first practical photosynthesis device, an artificial leaf of playing-card-size that can be used to mimic the process that green plants use to convert sunlight and water into energy.
The photosynthetic gadget, unveiled at a March 27 American Chemical Society meeting, uses sunlight to split water molecules into oxygen and hydrogen, and is reputedly 10 times more efficient than a natural leaf. Described as a milestones in the drive for sustainable energy, researchers say it will revolutionize power storage, especially in remote areas that don’t currently have electricity.
“We believe we have done it,” said Daniel Nocera, Ph.D., who led the research team. “The artificial leaf shows particular promise as an inexpensive source of electricity. Our goal is to make each home its own power station.”
Placed in a single gallon of water in bright sunlight, the device could produce enough electricity to supply a house in a developing country with electricity for a day, Nocera said. It does so by splitting water into its two components, hydrogen and oxygen.
Although they are the inspirational model for the development of this new genre of solar cells, the device bears no resemblance to natural leaves on oaks or maples. The same shape but thinner than a playing card, the device is fashioned from silicon, electronics and catalysts, substances that accelerate chemical reactions that otherwise would occur only slowly.
Right now, Nocera’s leaf is about 10 times more efficient at carrying out photosynthesis than a natural leaf. However, he is optimistic that he can boost the efficiency of the artificial leaf much higher in the future.
Nocera, who is with the Massachusetts Institute of Technology, points out that the “artificial leaf” is not a new concept. The first artificial leaf was developed more than a decade ago by John Turner of the U.S. National Renewable Energy Laboratory in Boulder, Colorado. Although highly efficient at carrying out photosynthesis, Turner’s device was impractical for wider use, as it was composed of rare, expensive metals and was highly unstable — with a lifespan of barely one day.
Nocera’s new leaf overcomes these problems. It is made of inexpensive materials that are widely available, works under simple conditions and is highly stable. In laboratory studies, he showed that an artificial leaf prototype could operate continuously for at least 45 hours without a drop in activity.
The key to this breakthrough is Nocera’s recent discovery of several powerful new, inexpensive catalysts, made of nickel and cobalt, that are capable of efficiently splitting water into its two components, hydrogen and oxygen, under simple conditions.
“Nature is powered by photosynthesis, and I think that the future world will be powered by photosynthesis as well in the form of this artificial leaf,” said Nocera, a chemist at Massachusetts Institute of Technology in Cambridge, Mass.
Nocera acknowledges funding from The National Science Foundation and Chesonis Family Foundation.