What if instead of turning to fossil fuels, wind or nuclear energy we couldobtain energy by using leaves like those used by green plants to trap energy from the sun? This is what Daniel Nocera, a chemist at the Massachusetts Institute of Technology (MIT), has just achieved, thus approaching the holy grail ofartificial photosynthesis. During the CCXLI meeting of the American Chemical Society, Nocera and her team presented aadvanced playing card size solar cellwhich simulates the process that green plants use to convert sunlight and water into energy.
? This artificial leaf is especially promising as acheap source of electrical energy for households in developing countries. Our goal is to make each home its own power station, “said Nocera.
The device does not resemble the leaves produced by nature, which scientists have nonetheless used as models in their efforts to develop this new type of solar cell. Its shape is that of a poker card, but thinner, and made from a silicon chip, electronic components and catalysts, substances that speed up chemical reactions that would not otherwise occur or would work slowly. Placed in a container with 3.7 liters of water and receiving bright sunlight, the device could produceenough energy to supply a house in a developing country with electricity for a dayNocera said. It does this by dividing water into its two components: hydrogen and oxygen.
? You could put it in a bottle of water, place it facing the sun, and we would see hydrogen and oxygen bubbles emerging ,? Nocera explained at a press conference. The chemistry of the device, which uses silicon, nickel and cobalt,emulates that of plants, which use energy from sunlight to produce electrons and positive charges within the leaf, and then split the water into oxygen and hydrogen, the latter trapped in carbohydrates. “Whether we realize it or not, the leaves are charged with electricity,” says Nocera.
Ten times more efficient than a natural leaf
Thefirst artificial leafIt was developedover a decade ago by John Turner, at the National Renewable Energy Laboratory, in Boulder, Colorado (USA). Although highly efficient at performing 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 just one day.
The new Nocera blade, by contrast, is made from widely available inexpensive materials. And in laboratory studies, the researcher showed that a prototype of the artificial leaf could operate continuously for at least 45 hours without decreased activity. Also, at this timethe artificial leaf is approximately 10 times more efficient in carrying out photosynthesis than a natural leaf.
