New 'Artificial Leaf' Reaps Sunlight for Energy Production
Scientists have unveiled what they claim is the first practical "artificial leaf," a development that could be a boon for generating sustainable energy.
The "leaf," which mimics photosynthesis, is actually an advanced solar cell the size of a poker card. Photosynthesis is the process that green plants use to convert sunlight and water into energy.
"A practical artificial leaf has been one of the holy grails of science for decades. We believe we have done it," Daniel Nocera, a chemist at the Massachusetts Institute of Technology, said in a statement. "The artificial leaf shows particular promise as an inexpensive source of electricity for homes of the poor in developing countries."
Nocera led the research team.
The device bears no resemblance to Mother Nature's counterparts on oaks, maples and other green plants, but scientists used real leaves — which use carbon dioxide and sunlight to produce sugar and oxygen — as the models for their efforts to develop this new genre of solar cells.
About the shape of a playing card but thinner, the device is fashioned from silicon, electronics and catalysts, substances that accelerate chemical reactions that otherwise would occur slowly or not at all.
Placed in a single gallon of water in bright sunlight, the device could produce enough electricity to supply a house in a developing country for a day, Nocera said.
It works by splitting the water into its two components, hydrogen and oxygen. The hydrogen and oxygen gases would be stored in a fuel cell , which uses those two materials to produce electricity. The fuel cell would be located either on top of the house or beside it.
Nocera points out that the artificial leaf is not a new concept. The first one was developed more than a decade ago by John Turner of the U.S. National Renewable Energy Laboratory in Boulder, Colo. Although highly efficient at carrying out photosynthesis, Turner's device was impractical for wider use: It was composed of rare, expensive metals and was highly unstable — with a lifespan of barely one day.
Nocera's leaf overcomes these problems. It is made of inexpensive materials that are widely available, works under simple conditions and is highly stable, he said. In laboratory studies, a prototype operated continuously for 45 hours without a drop in activity.
The key to this breakthrough is the recent discovery of several powerful new, inexpensive catalysts made of nickel and cobalt that are capable of efficiently splitting water into hydrogen and oxygen under simple conditions.
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 eventually boost its efficiency much further.
"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. "Our goal is to make each home its own power station. One can envision villages in India and Africa not long from now purchasing an affordable basic power system based on this technology."
The findings were presented at the 241st National Meeting of the American Chemical Society.