EMBARGOED FOR RELEASE聽|聽April 08, 2013
鈥楢rtificial leaf鈥� gains the ability to self-heal damage and produce energy from dirty water
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NEW ORLEANS, April 8, 2013 鈥� Another innovative feature has been added to the world鈥檚 first practical 鈥渁rtificial leaf,鈥� making the device even more suitable for providing people in developing countries and remote areas with electricity, scientists reported here today. It gives the leaf the ability to self-heal damage that occurs during production of energy.
Daniel G. Nocera, Ph.D., described the advance during the 鈥淜avli Foundation Innovations in Chemistry Lecture鈥� at the 245th National Meeting & Exposition of the American Chemical 中国365bet中文官网, the world鈥檚 largest scientific society. About 14,000 scientists and others are expected for the meeting, which continues through Thursday with almost 12,000 reports on advances in science.
Nocera, leader of the research team, explained that the 鈥渓eaf鈥� mimics the ability of real leaves to produce energy from sunlight and water. The device, however, actually is a simple catalyst-coated wafer of silicon, rather than a complicated reproduction of the photosynthesis mechanism in real leaves. Dropped into a jar of water and exposed to sunlight, catalysts in the device break water down into its components, hydrogen and oxygen. Those gases bubble up and can be collected and used as fuel to produce electricity in fuel cells.
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鈥淪urprisingly, some of the catalysts we鈥檝e developed for use in the artificial leaf device actually heal themselves,鈥� Nocera said. 鈥淭hey are a kind of 鈥榣iving catalyst.鈥� This is an important innovation that eases one of the concerns about initial use of the leaf in developing countries and other remote areas.鈥�
Nocera, who is the Patterson Rockwood Professor of Energy at Harvard University, explained that the artificial leaf likely would find its first uses in providing 鈥減ersonalized鈥� electricity to individual homes in areas that lack traditional electric power generating stations and electric transmission lines. Less than one quart of drinking water, for instance, would be enough to provide about 100 watts of electricity 24 hours a day. Earlier versions of the leaf required pure water, because bacteria eventually formed biofilms on the leaf鈥檚 surface, shutting down production.
鈥淪elf-healing enables the artificial leaf to run on the impure, bacteria-contaminated water found in nature,鈥� Nocera said. 鈥淲e 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.鈥�
Nocera said that about 3 billion people today live in areas that lack access to traditional electric production and distribution systems. That population will grow by billions in the decades ahead. About 1 billion people in the developing world already lack reliable access to clean water. Thus, a clear need exists for a simple device like the artificial leaf that鈥檚 compatible with local conditions.
鈥淚t鈥檚 kind of like providing 鈥榝ast-food energy,鈥欌€� he noted. 鈥淲e鈥檙e interested in making lots of inexpensive units that may not be the most efficient, but that get the job done. It鈥檚 kind of like going from huge mainframe computers to a personal laptop. This is personalized energy.鈥�
Earlier devices used rare, costly metals and other materials, involved complicated wiring and were expensive to manufacture. But Nocera鈥檚 artificial leaf uses less-expensive materials and incorporates a design 鈥� a so-called 鈥渂uried junction鈥� 鈥� that is simple and would be inexpensive to mass produce. And the leaf has advantages over solar panels, which are costly and produce energy only during daylight hours. The leaf鈥檚 hydrogen and oxygen, in contrast, can be stored and used at night.
鈥淎 lot of people are designing complicated, expensive energy-producing devices, and it is difficult to see them being adopted on a large scale,鈥� he said. 鈥淥urs is simple, less expensive, and it works. And with that, I think we鈥檝e changed the dialog in the field.鈥�
Among the team鈥檚 priorities for further development of the device: integrating it with technology for converting the hydrogen into a liquid fuel that could run traditional portable electric generators or even cars.
Sponsored by The Kavli Foundation, a philanthropic organization that supports basic scientific research, Nocera鈥檚 talk is part of a series of designed to address the urgent need for vigorous, 鈥渙utside the box鈥� thinking by scientists as they tackle the world鈥檚 mounting challenges, including climate change, emerging diseases and water and energy shortages.
鈥淲e are dedicated to advancing science for the benefit of humanity, promoting public understanding of scientific research and supporting scientists and their work,鈥� said Kavli Foundation President Robert W. Conn in a statement. 鈥淭he Kavli Foundation Innovations in Chemistry Lecture program at the ACS national meetings fits perfectly with our commitment to support groundbreaking discovery and promote public understanding.鈥�
The Kavli lectures debuted at the Anaheim meeting in March 2011 and will continue through 2013. They will address the urgent need for vigorous, new, 鈥渙utside-the-box鈥� thinking, as scientists tackle many of the world鈥檚 mounting challenges like climate change, emerging diseases and water and energy shortages. The , an internationally recognized philanthropic organization known for its support of basic scientific innovation, agreed to sponsor the lectures in conjunction with ACS in 2010.
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