Small in Size, Big On Power: New Microbatteries the Most Powerful Yet

Small in Size, Big On Power: New Microbatteries the Most Powerful Yet

  9:32:00 AM    Science Lover

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Though they be but little, they are fierce. The most powerful batteries on the planet are only a few millimeters in size, yet they pack such a punch that a driver could use a cellphone powered by these batteries to jump-start a dead car battery -- and then recharge the phone in the blink of an eye. 

The graphic illustrates a high power battery technology from the University of Illinois. Ions flow between three-dimensional micro-electrodes in a lithium ion battery. (Credit: Image courtesy of the Beckman Institute for Advanced Science and Technology)

Developed by researchers at the University of Illinois at Urbana-Champaign, the new microbatteries out-power even the best supercapacitors and could drive new applications in radio communications and compact electronics.

Led by William P. King, the Bliss Professor of mechanical science and engineering, the researchers published their results in the April 16 issue of Nature Communications.

"This is a whole new way to think about batteries," King said. "A battery can deliver far more power than anybody ever thought. In recent decades, electronics have gotten small. The thinking parts of computers have gotten small. And the battery has lagged far behind. This is a microtechnology that could change all of that. Now the power source is as high-performance as the rest of it."

With currently available power sources, users have had to choose between power and energy. For applications that need a lot of power, like broadcasting a radio signal over a long distance, capacitors can release energy very quickly but can only store a small amount. For applications that need a lot of energy, like playing a radio for a long time, fuel cells and batteries can hold a lot of energy but release it or recharge slowly.

"There's a sacrifice," said James Pikul, a graduate student and first author of the paper. "If you want high energy you can't get high power; if you want high power it's very difficult to get high energy. But for very interesting applications, especially modern applications, you really need both. That's what our batteries are starting to do. We're really pushing into an area in the energy storage design space that is not currently available with technologies today."

The new microbatteries offer both power and energy, and by tweaking the structure a bit, the researchers can tune them over a wide range on the power-versus-energy scale.

The batteries owe their high performance to their internal three-dimensional microstructure. Batteries have two key components: the anode (minus side) and cathode (plus side). Building on a novel fast-charging cathode design by materials science and engineering professor Paul Braun's group, King and Pikul developed a matching anode and then developed a new way to integrate the two components at the microscale to make a complete battery with superior performance.

With so much power, the batteries could enable sensors or radio signals that broadcast 30 times farther, or devices 30 times smaller. The batteries are rechargeable and can charge 1,000 times faster than competing technologies -- imagine juicing up a credit-card-thin phone in less than a second. In addition to consumer electronics, medical devices, lasers, sensors and other applications could see leaps forward in technology with such power sources available.

"Any kind of electronic device is limited by the size of the battery -- until now," King said. "Consider personal medical devices and implants, where the battery is an enormous brick, and it's connected to itty-bitty electronics and tiny wires. Now the battery is also tiny."

Now, the researchers are working on integrating their batteries with other electronics components, as well as manufacturability at low cost.

"Now we can think outside of the box," Pikul said. "It's a new enabling technology. It's not a progressive improvement over previous technologies; it breaks the normal paradigms of energy sources. It's allowing us to do different, new things."

The National Science Foundation and the Air Force Office of Scientific Research supported this work. King also is affiliated with the Beckman Institute for Advanced Science and Technology; the Frederick Seitz Materials Research Laboratory; the Micro and Nanotechnology Laboratory; and the department of electrical and computer engineering at the U. of I.

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Artificial leaves make fuel from sunlight

Artificial leaves make fuel from sunlight

  10:06:00 AM    Science Lover

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Two teams of researchers in the US have taken important steps towards the creation of commercially viable "artificial leaf" – a hypothetical device that can turn sunlight into electrical energy or fuel by mimicking some aspects of photosynthesis.

Daniel Nocera in his lab at the
Massachusetts Institute of Technology.
(Courtesy: Donna Coveney/MIT)

Earlier this year, the chemist Daniel Nocera at the Massachusetts Institute of Technology (MIT) announced artificial-leaf prototypes at the annual meeting of the American Chemical Society in California. Now, working with two different teams of researchers, he has published two papers on different devices that represent progress towards effective and commercially viable versions of the artificial leaf.

Here comes the Sun

Both teams made their devices from silicon wafers that are coated with catalytic metals and protective layers. The prototype solar cells are about the size of a credit card and can capture sunlight and then use the energy to split water into its constituent oxygen and hydrogen. This is different to conventional photovoltaic cells, which convert light directly into electricity. With these new devices, the ultimate plan is to recombine the two gases in an integrated fuel cell, thus converting the chemical energy to electrical energy. Producing fuel rather than electricity has the advantage that the fuel can be easily stored until it is needed.

Both artificial leaves use a silicon n–p junction: a bilayer of n-type and p-type silicon. An incident photon is absorbed to create an electron–hole pair in the semiconductor. The electrons migrate to the n-side and the holes to the p-side. The holes then drive the splitting of water in a process mediated by the outermost layer of the cell, which is a photocatalyst. Unlike some of the exotic photocatalysts used in earlier devices, the catalyst in these new devices are made of cobalt phosphate, which is an abundant and cheap material.

The main challenge in creating both devices was how to prevent the silicon from reacting with the water. The two teams took different approaches to the problem. One group led by electrical engineer Vladimir Bulovic used the catalyst itself as a protective layer, binding a thin film of pure cobalt firmly to the silicon before converting it to the phosphate form. The other team, led by mechanical engineer Tonio Buonassisi, used a thin film of conductive indium tin oxide in front of the p-type silicon as the protective layer.

Bubbles needed



Buonassisi and colleagues connected two of their cells in series and managed to split water with a solar-to-oxygen conversion efficiency of 0.25%. While this does not sound like much, the efficiency of photosynthesis is only a few per cent. However, the cells make hydrogen ions, and turning this into gas could add considerable cost to the device. "Platinum electrodes are good catalysts for reducing hydrogen ions to hydrogen gas", says Devens Gust of Arizona State University, who was not involved in the research. "However, the rarity of platinum limits its usefulness."

Gust describes the MIT work as "very important in that it demonstrates a workable, inexpensive water-oxidation catalyst". However, he says that the technology is entering a crowded market, pointing out that there is already a production technology for solar fuel that is "pretty much ready to go now". This system uses photovoltaic cells coupled to an electrolyzer that splits water into oxygen and hydrogen. "Electrolyzer efficiencies can be as high as 70–80%, and currently available photovoltaic efficiencies are as high as 15–20%", he points out. "None of the artificial photosynthetic systems can compete with this at the moment."

The MIT technology must also compete with other water-splitting systems based on silicon solar cells coated with photocatalysts. These have been in development since at least 1998 and some have reached solar-to-hydrogen conversion efficiencies of 7% or better.

"Challenges remain"

One of these cells was developed at California Institute of Technology by Nathan Lewis and Harry Atwater. Atwater told physicsworld.com that "Nocera's work is interesting, but many challenges remain." It is not clear, for example, whether the catalyst and devices remain stable beyond the few days of operation for which they have so far been tested. Atwater also thinks there is room for improvement in the materials themselves.

Gust agrees, pointing out that while cobalt and other catalysts based on common materials are promising, researchers have yet to develop an inexpensive catalyst that works near the thermodynamic potential for water oxidation/reduction. This property would help to optimize the performance of an artificial-leaf system. Nocera hopes to have a fully working device within about three years, and he has formed a company called SunCatalytix to develop it.

The work by Bulovic's group is published in Energy & Environmental Science, while the research by Buonassisi's group is outlined in Proceedings of the National Academy of Sciences USA.

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New Way to Store Sun's Heat: Modified Carbon Nanotubes Can Store Solar Energy Indefinitely, Then Be Recharged by Exposure to the Sun

New Way to Store Sun's Heat: Modified Carbon Nanotubes Can Store Solar Energy Indefinitely, Then Be Recharged by Exposure to the Sun

  12:25:00 AM    Science Lover

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A novel application of carbon nanotubes, developed by MIT researchers, shows promise as an innovative approach to storing solar energy for use whenever it's needed.

Illustration. (Credit: Image courtesy of Grossman/Kolpak)

Storing the sun's heat in chemical form -- rather than converting it to electricity or storing the heat itself in a heavily insulated container -- has significant advantages, since in principle the chemical material can be stored for long periods of time without losing any of its stored energy. The problem with that approach has been that until now the chemicals needed to perform this conversion and storage either degraded within a few cycles, or included the element ruthenium, which is rare and expensive.

Last year, MIT associate professor Jeffrey Grossman and four co-authors figured out exactly how fulvalene diruthenium -- known to scientists as the best chemical for reversibly storing solar energy, since it did not degrade -- was able to accomplish this feat. Grossman said at the time that better understanding this process could make it easier to search for other compounds, made of abundant and inexpensive materials, which could be used in the same way.

Now, he and postdoc Alexie Kolpak have succeeded in doing just that. A paper describing their new findings has just been published online in the journal Nano Letters, and will appear in print in a forthcoming issue.

The new material found by Grossman and Kolpak is made using carbon nanotubes, tiny tubular structures of pure carbon, in combination with a compound called azobenzene. The resulting molecules, produced using nanoscale templates to shape and constrain their physical structure, gain "new properties that aren't available" in the separate materials, says Grossman, the Carl Richard Soderberg Associate Professor of Power Engineering.

Not only is this new chemical system less expensive than the earlier ruthenium-containing compound, but it also is vastly more efficient at storing energy in a given amount of space -- about 10,000 times higher in volumetric energy density, Kolpak says -- making its energy density comparable to lithium-ion batteries. By using nanofabrication methods, "you can control [the molecules'] interactions, increasing the amount of energy they can store and the length of time for which they can store it -- and most importantly, you can control both independently," she says.

Thermo-chemical storage of solar energy uses a molecule whose structure changes when exposed to sunlight, and can remain stable in that form indefinitely. Then, when nudged by a stimulus -- a catalyst, a small temperature change, a flash of light -- it can quickly snap back to its other form, releasing its stored energy in a burst of heat. Grossman describes it as creating a rechargeable heat battery with a long shelf life, like a conventional battery.



One of the great advantages of the new approach to harnessing solar energy, Grossman says, is that it simplifies the process by combining energy harvesting and storage into a single step. "You've got a material that both converts and stores energy," he says. "It's robust, it doesn't degrade, and it's cheap." One limitation, however, is that while this process is useful for heating applications, to produce electricity would require another conversion step, using thermoelectric devices or producing steam to run a generator.

While the new work shows the energy-storage capability of a specific type of molecule -- azobenzene-functionalized carbon nanotubes -- Grossman says the way the material was designed involves "a general concept that can be applied to many new materials." Many of these have already been synthesized by other researchers for different applications, and would simply need to have their properties fine-tuned for solar thermal storage.

The key to controlling solar thermal storage is an energy barrier separating the two stable states the molecule can adopt; the detailed understanding of that barrier was central to Grossman's earlier research on fulvalene dirunthenium, accounting for its long-term stability. Too low a barrier, and the molecule would return too easily to its "uncharged" state, failing to store energy for long periods; if the barrier were too high, it would not be able to easily release its energy when needed. "The barrier has to be optimized," Grossman says.

Already, the team is "very actively looking at a range of new materials," he says. While they have already identified the one very promising material described in this paper, he says, "I see this as the tip of the iceberg. We're pretty jazzed up about it."

Yosuke Kanai, assistant professor of chemistry at the University of North Carolina at Chapel Hill, says "the idea of reversibly storing solar energy in chemical bonds is gaining a lot of attention these days. The novelty of this work is how these authors have shown that the energy density can be significantly increased by using carbon nanotubes as nanoscale templates. This innovative idea also opens up an interesting avenue for tailoring already-known photoactive molecules for solar thermal fuels and storage in general."

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Inkjet Printing Could Change the Face of Solar Energy Industry

Inkjet Printing Could Change the Face of Solar Energy Industry

  9:33:00 AM    Science Lover

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Inkjet printers, a low-cost technology that in recent decades has revolutionized home and small office printing, may soon offer similar benefits for the future of solar energy.

Solar cell. This scanning electron microscope, 
cross-sectional image shows the various compounds 
of a new chalcopyrite solar cell only a few microns
thick, which can be created much less expensively with
inkjet printing. (Credit: Oregon State University)

Engineers at Oregon State University have discovered a way for the first time to create successful "CIGS" solar devices with inkjet printing, in work that reduces raw material waste by 90 percent and will significantly lower the cost of producing solar energy cells with some very promising compounds.

High performing, rapidly produced, ultra-low cost, thin film solar electronics should be possible, scientists said.

The findings have been published in Solar Energy Materials and Solar Cells, a professional journal, and a patent applied for on the discovery. Further research is needed to increase the efficiency of the cell, but the work could lead to a whole new generation of solar energy technology, researchers say.

"This is very promising and could be an important new technology to add to the solar energy field," said Chih-hung Chang, an OSU professor in the School of Chemical, Biological and Environmental Engineering. "Until now no one had been able to create working CIGS solar devices with inkjet technology."

Part of the advantage of this approach, Chang said, is a dramatic reduction in wasted material. Instead of depositing chemical compounds on a substrate with a more expensive vapor phase deposition -- wasting most of the material in the process -- inkjet technology could be used to create precise patterning with very low waste.

"Some of the materials we want to work with for the most advanced solar cells, such as indium, are relatively expensive," Chang said. "If that's what you're using you can't really afford to waste it, and the inkjet approach almost eliminates the waste."



One of the most promising compounds and the focus of the current study is called chalcopyrite, or "CIGS" for the copper, indium, gallium and selenium elements of which it's composed. CIGS has extraordinary solar efficiency -- a layer of chalcopyrite one or two microns thick has the ability to capture the energy from photons about as efficiently as a 50-micron-thick layer made with silicon.

In the new findings, researchers were able to create an ink that could print chalcopyrite onto substrates with an inkjet approach, with a power conversion efficiency of about 5 percent. The OSU researchers say that with continued research they should be able to achieve an efficiency of about 12 percent, which would make a commercially viable solar cell.

In related work, being done in collaboration with Greg Herman, an OSU associate professor of chemical engineering, the engineers are studying other compounds that might also be used with inkjet technology, and cost even less.

Some approaches to producing solar cells are time consuming, or require expensive vacuum systems or toxic chemicals. OSU experts are working to eliminate some of those roadblocks and create much less costly solar technology that is also more environmentally friendly. New jobs and industries in the Pacific Northwest could evolve from such initiatives, they say.

If costs can be reduced enough and other hurdles breached, it might even be possible to create solar cells that could be built directly into roofing materials, scientists say, opening a huge new potential for solar energy.

"In summary, a simple, fast, and direct-write, solution-based deposition process is developed for the fabrication of high quality CIGS solar cells," the researchers wrote in their conclusion. "Safe, cheap, and air-stable inks can be prepared easily by controlling the composition of low-cost metal salt precursors at a molecular level."

This work was supported by the Daegu Gyeongbuk Institute of Science and Technology, the U.S. Department of Energy and OSU's University Venture Development Fund, which helps donors receive tax benefits while sponsoring projects that will bring new technology, jobs and economic growth to Oregon.

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New Reactor to Make Fuel from Sunlight

New Reactor to Make Fuel from Sunlight

  8:13:00 PM    Science Lover

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Using a common metal most famously found in self-cleaning ovens, Sossina Haile hopes to change our energy future. The metal is cerium oxide -- or ceria -- and it is the centerpiece of a promising new technology developed by Haile and her colleagues that concentrates solar energy and uses it to efficiently convert carbon dioxide and water into fuels.

Sossina Haile and William Chueh stand next to the 
benchtop thermochemical reactor used to screen 
materials for implementation on the solar reactor. 
(Credit: Courtesy of Caltech)

Solar energy has long been touted as the solution to our energy woes, but while it is plentiful and free, it can't be bottled up and transported from sunny locations to the drearier -- but more energy-hungry -- parts of the world. The process developed by Haile -- a professor of materials science and chemical engineering at the California Institute of Technology (Caltech) -- and her colleagues could make that possible.

The researchers designed and built a two-foot-tall prototype reactor that has a quartz window and a cavity that absorbs concentrated sunlight. The concentrator works "like the magnifying glass you used as a kid" to focus the sun's rays, says Haile.

At the heart of the reactor is a cylindrical lining of ceria. Ceria -- a metal oxide that is commonly embedded in the walls of self-cleaning ovens, where it catalyzes reactions that decompose food and other stuck-on gunk -- propels the solar-driven reactions. The reactor takes advantage of ceria's ability to "exhale" oxygen from its crystalline framework at very high temperatures and then "inhale" oxygen back in at lower temperatures.

"What is special about the material is that it doesn't release all of the oxygen. That helps to leave the framework of the material intact as oxygen leaves," Haile explains. "When we cool it back down, the material's thermodynamically preferred state is to pull oxygen back into the structure."

Specifically, the inhaled oxygen is stripped off of carbon dioxide (CO2) and/or water (H2O) gas molecules that are pumped into the reactor, producing carbon monoxide (CO) and/or hydrogen gas (H2). H2 can be used to fuel hydrogen fuel cells; CO, combined with H2, can be used to create synthetic gas, or "syngas," which is the precursor to liquid hydrocarbon fuels. Adding other catalysts to the gas mixture, meanwhile, produces methane. And once the ceria is oxygenated to full capacity, it can be heated back up again, and the cycle can begin anew.

For all of this to work, the temperatures in the reactor have to be very high -- nearly 3,000 degrees Fahrenheit. At Caltech, Haile and her students achieved such temperatures using electrical furnaces. But for a real-world test, she says, "we needed to use photons, so we went to Switzerland." At the Paul Scherrer Institute's High-Flux Solar Simulator, the researchers and their collaborators -- led by Aldo Steinfeld of the institute's Solar Technology Laboratory -- installed the reactor on a large solar simulator capable of delivering the heat of 1,500 suns.

In experiments conducted last spring, Haile and her colleagues achieved the best rates for CO2 dissociation ever achieved, "by orders of magnitude," she says. The efficiency of the reactor was uncommonly high for CO2 splitting, in part, she says, "because we're using the whole solar spectrum, and not just particular wavelengths." And unlike in electrolysis, the rate is not limited by the low solubility of CO2 in water. Furthermore, Haile says, the high operating temperatures of the reactor mean that fast catalysis is possible, without the need for expensive and rare metal catalysts (cerium, in fact, is the most common of the rare earth metals -- about as abundant as copper).

In the short term, Haile and her colleagues plan to tinker with the ceria formulation so that the reaction temperature can be lowered, and to re-engineer the reactor, to improve its efficiency. Currently, the system harnesses less than 1% of the solar energy it receives, with most of the energy lost as heat through the reactor's walls or by re-radiation through the quartz window. "When we designed the reactor, we didn't do much to control these losses," says Haile. Thermodynamic modeling by lead author and former Caltech graduate student William Chueh suggests that efficiencies of 15% or higher are possible.

Ultimately, Haile says, the process could be adopted in large-scale energy plants, allowing solar-derived power to be reliably available during the day and night. The CO2 emitted by vehicles could be collected and converted to fuel, "but that is difficult," she says. A more realistic scenario might be to take the CO2 emissions from coal-powered electric plants and convert them to transportation fuels. "You'd effectively be using the carbon twice," Haile explains. Alternatively, she says, the reactor could be used in a "zero CO2 emissions" cycle: H2O and CO2 would be converted to methane, would fuel electricity-producing power plants that generate more CO2 and H2O, to keep the process going.

The work was funded by the National Science Foundation, the State of Minnesota Initiative for Renewable Energy and the Environment, and the Swiss National Science Foundation.

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Advance Boosts Potential for Solar Fuel

Advance Boosts Potential for Solar Fuel

  4:05:00 PM    Science Lover

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Emory University chemists have developed the most potent homogeneous catalyst known for water oxidation, considered a crucial component for generating clean hydrogen fuel using only water and sunlight.

Chemists have developed the most potent homogeneous catalyst known for water oxidation, considered a crucial component for generating clean hydrogen fuel using only water and sunlight. (Credit: Photo by Benjamin Yin, Emory University)

The breakthrough, published March 11 in the journal Science, was made in collaboration with the Paris Institute of Molecular Chemistry.

The fastest, carbon-free molecular water oxidation catalyst (WOC) to date "has really upped the standard from the other known homogeneous WOCs," said Emory inorganic chemist Craig Hill, whose lab led the effort. "It's like a home run compared to a base hit."

In order to be viable, a WOC needs selectivity, stability and speed. Homogeneity is also a desired trait, since it boosts efficiency and makes the WOC easer to study and optimize. The new WOC has all of these qualities, and it is based on the cheap and abundant element cobalt, adding to its potential to help solar energy go mainstream.

Benjamin Yin, an undergraduate student in Hill's lab, is the lead author on the Science paper. Emory chemists who are co-authors include Hill, Yurii Geletii, Jamal Musaev, Zhen Luo and Ken Hardcastle. The U.S. Department of Energy funded the work.

The WOC research is a component of the Emory Bio-inspired Renewable Energy Center, which aims to mimic natural processes such as photosynthesis to generate clean fuel. The next step involves incorporating the WOC into a solar-driven, water-splitting system.

The long-term goal is to use sunlight to split water into oxygen and hydrogen. Hydrogen becomes the fuel. Its combustion produces the by-product of water -- which flows back into a clean, green, renewable cycle.

Three main technical challenges are involved: developing a light collector, a catalyst to oxidize water to oxygen and a catalyst to reduce water to hydrogen. All three components need improvement, but a viable WOC may be the most difficult scientific challenge. "We are aiming for a WOC that is free of organic structure, because organic components will combine with oxygen and self-destruct," Hill says. "You'll wind up with a lot of gunk."

Enzymes are nature's catalysts. The enzyme in the oxygen-evolving center of green plants "is about the least stable catalyst in nature, and one of the shortest lived, because it's doing one of the hardest jobs," Hill says.

"We've duplicated this complex natural process by taking some of the essential features from photosynthesis and using them in a synthetic, carbon-free, homogeneous system. The result is a water oxidation catalyst that is far more stable than the one found in nature."

For decades, scientists have been trying to imitate Mother Nature and create a WOC for artificial photosynthesis. Nearly all of the more than 40 homogeneous WOCs developed by labs have had significant limitations, such as containing organic components that burn up quickly during the water oxidation process.

Two years ago, Hill's lab and collaborators developed the first prototype of a stable, homogenous, carbon-free WOC, which also worked faster than others known at the time. The prototype, however, was based on ruthenium, a relatively rare and expensive element.

Building on that work, the researchers began experimenting with the cheaper and more abundant element cobalt. The cobalt-based WOC has proved even faster than the ruthenium version for light-driven water oxidation.

For more information on sustainable energy research at Emory, go to: http://www.emory.edu/home/news/special/green-energy/

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Frogs, Foam and Fuel: Solar Energy Converted to Sugars

Frogs, Foam and Fuel: Solar Energy Converted to Sugars

  1:14:00 AM    Science Lover

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For decades, farmers have been trying to find ways to get more energy out of the sun. In natural photosynthesis, plants take in solar energy and carbon dioxide and then convert it to oxygen and sugars. The oxygen is released to the air and the sugars are dispersed throughout the plant -- like that sweet corn we look for in the summer. Unfortunately, the allocation of light energy into products we use is not as efficient as we would like. Now engineering researchers at the University of Cincinnati are doing something about that.

In natural photosynthesis, plants take in solar energy and carbon dioxide and then convert it to oxygen and sugars. (Credit: Image courtesy of University of Cincinnati, Illustration by Megan Gundrum, fifth-year DAAP student)

The researchers are finding ways to take energy from the sun and carbon from the air to create new forms of biofuels, thanks to a semi-tropical frog species. Their results have just been published online in Nano Letters.

Research Assistant Professor David Wendell, student Jacob Todd and College of Engineering and Applied Science Dean Carlo Montemagno co-authored the paper, based on research in Montemagno's lab in the Department of Biomedical Engineering. Their work focused on making a new artificial photosynthetic material which uses plant, bacterial, frog and fungal enzymes, trapped within a foam housing, to produce sugars from sunlight and carbon dioxide.

Foam was chosen because it can effectively concentrate the reactants but allow very good light and air penetration. The design was based on the foam nests of a semi-tropical frog called the Tungara frog, which creates very long-lived foams for its developing tadpoles.

"The advantage for our system compared to plants and algae is that all of the captured solar energy is converted to sugars, whereas these organisms must divert a great deal of energy to other functions to maintain life and reproduce," says Wendell. "Our foam also uses no soil, so food production would not be interrupted, and it can be used in highly enriched carbon dioxide environments, like the exhaust from coal-burning power plants, unlike many natural photosynthetic systems."

He adds, "In natural plant systems, too much carbon dioxide shuts down photosynthesis, but ours does not have this limitation due to the bacterial-based photo-capture strategy."

There are many benefits to being able to create a plant-like foam.

"You can convert the sugars into many different things, including ethanol and other biofuels," Wendell explains. "And it removes carbon dioxide from the air, but maintains current arable land for food production."

"This new technology establishes an economical way of harnessing the physiology of living systems by creating a new generation of functional materials that intrinsically incorporates life processes into its structure," says Dean Montemagno. "Specifically in this work it presents a new pathway of harvesting solar energy to produce either oil or food with efficiencies that exceed other biosolar production methodologies. More broadly it establishes a mechanism for incorporating the functionality found in living systems into systems that we engineer and build."

The next step for the team will be to try to make the technology feasible for large-scale applications like carbon capture at coal-burning power plants.

"This involves developing a strategy to extract both the lipid shell of the algae (used for biodiesel) and the cytoplasmic contents (the guts), and reusing these proteins in the foam," says Wendell. "We are also looking into other short carbon molecules we can make by altering the enzyme cocktail in the foam."

Montemagno adds, "It is a significant step in delivering the promise of nanotechnology."

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Photosynthesis: A New Source of Electrical Energy? Biofuel Cell Works in Cactus

Photosynthesis: A New Source of Electrical Energy? Biofuel Cell Works in Cactus

  1:08:00 AM    Science Lover

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Scientists in France have transformed the chemical energy generated by photosynthesis into electrical energy by developing a novel biofuel cell. The advance offers a new strategy to convert solar energy into electrical energy in an environmentally-friendly and renewable manner. In addition, the biofuel cell could have important medical applications.

Biofuel cell inserted in a cactus and graph showing the course of electrical current as a function of illumination of the cactus (black: glucose, red: O2)

These findings have just been published in the journal Analytical Chemistry.

Photosynthesis is the process by which plants convert solar energy into chemical energy. In the presence of visible light, carbon dioxide (CO₂) and water (H₂0) are transformed into glucose and O₂ during a complex series of chemical reactions. Researchers at the Centre de Recherche Paul Pascal (CNRS) developed a biofuel cell that functions using the products of photosynthesis (glucose and O₂) and is made up of two enzyme-modified electrodes.

The cell was then inserted in a living plant, in this case a cactus. Once the electrodes, highly sensitive to O₂ and glucose, had been implanted in the cactus leaf, the scientists succeeded in monitoring the real-time course of photosynthesis in vivo. They were able to observe an increase in electrical current when a desk lamp was switched on, and a reduction when it was switched off. During these experiments, the scientists were also able to make the first ever observation of the real-time course of glucose levels during photosynthesis. This method could offer a new means of better understanding the mechanisms of photosynthesis.

Furthermore, the researchers showed that a biofuel cell inserted in a cactus leaf could generate power of 9 μW per cm². Because this yield was proportional to light intensity, stronger illumination accelerated the production of glucose and O₂ (photosynthesis), so more fuel was available to operate the cell. In the future, this system could ultimately form the basis for a new strategy for the environmentally-friendly and renewable transformation of solar energy into electrical energy.

Alongside these results, the initial objective of this work was to develop a biofuel cell for medical applications. This could then function autonomously under the skin (in vivo), drawing chemical energy from the oxygen-glucose couple that is naturally present in physiological fluids. It could thus provide power for implanted medical devices such as, for example, autonomous subcutaneous sensors to measure glucose levels in diabetic patients.

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Glitter-Sized Solar Photovoltaics Could Revolutionize the Way Solar Energy Is Collected and Used

Glitter-Sized Solar Photovoltaics Could Revolutionize the Way Solar Energy Is Collected and Used

  1:21:00 AM    Science Lover

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Sandia National Laboratories scientists have developed tiny glitter-sized photovoltaic cells that could revolutionize the way solar energy is collected and used.

Representative thin crystalline-silicon photovoltaic cells -- these are from 14 to 20 micrometers thick and 0.25 to 1 millimeter across. (Credit: Image by Murat Okandan)

The tiny cells could turn a person into a walking solar battery charger if they were fastened to flexible substrates molded around unusual shapes, such as clothing.

The solar particles, fabricated of crystalline silicon, hold the potential for a variety of new applications. They are expected eventually to be less expensive and have greater efficiencies than current photovoltaic collectors that are pieced together with 6-inch- square solar wafers.

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New Nano-Material May Revolutionize Solar Panels and Batteries

New Nano-Material May Revolutionize Solar Panels and Batteries

  11:03:00 PM    Science Lover

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A coating on windows or solar panels that repels grime and dirt? Expanded battery storage capacities for the next electric car? New Tel Aviv University research, just published in Nature Nanotechnology, details a breakthrough in assembling peptides at the nano-scale level that could make these futuristic visions come true in just a few years.

TAU's nanosized "forest of peptides" can be used as the basis for self-cleaning windows and more efficient batteries. (Credit: Image courtesy of American Friends of Tel Aviv University)

Operating in the range of 100 nanometers (roughly one-billionth of a meter) and even smaller, graduate student Lihi Adler-Abramovich and a team working under Prof. Ehud Gazit in TAU's Department of Molecular Microbiology and Biotechnology have found a novel way to control the atoms and molecules of peptides so that they "grow" to resemble small forests of grass. These "peptide forests" repel dust and water -- a perfect self-cleaning coating for windows or solar panels which, when dirty, become far less efficient.

"This is beautiful and protean research," says Adler-Abramovich, a Ph.D. candidate. "It began as an attempt to find a new cure for Alzheimer's disease. To our surprise, it also had implications for electric cars, solar energy and construction."

As cheap as the sweetener in your soda

A world leader in nanotechnology research, Prof. Gazit has been developing arrays of self-assembling peptides made from proteins for the past six years. His lab, in collaboration with a group led by Prof. Gil Rosenman of TAU's Faculty of Engineering, has been working on new applications for this basic science for the last two years.

Using a variety of peptides, which are as simple and inexpensive to produce as the artificial sweetener aspartame, the researchers create their "self-assembled nano-tubules" in a vacuum under high temperatures. These nano-tubules can withstand extreme heat and are resistant to water.

"We are not manufacturing the actual material but developing a basic-science technology that could lead to self-cleaning windows and more efficient energy storage devices in just a few years," says Adler-Abramovich. "As scientists, we focus on pure research. Thanks to Prof. Gazit's work on beta amyloid proteins, we were able to develop a technique that enables short peptides to 'self-assemble,' forming an entirely new kind of coating which is also a super-capacitor."

As a capacitor with unusually high energy density, the nano-tech material could give existing electric batteries a boost -- necessary to start an electric car, go up a hill, or pass other cars and trucks on the highway. One of the limitations of the electric car is thrust, and the team thinks their research could lead to a solution to this difficult problem.

"Our technology may lead to a storage material with a high density," says Adler-Abramovich. "This is important when you need to generate a lot of energy in a short period of time. It could also be incorporated into today's lithium batteries," she adds.

Window Cleaner a thing of the past?

Coated with the new material, the sealed outer windows of skyscrapers may never need to be washed again -- the TAU lab's material can repel rainwater, as well as the dust and dirt it carries. The efficiency of solar energy panels could be improved as well, as a rain shower would pull away any dust that might have accumulated on the panels. It means saving money on maintenance and cleaning, which is especially a problem in dusty deserts, where most solar farms are installed today.

The lab has already been approached to develop its coating technology commercially. And Prof. Gazit has a contract with drug mega-developer Merck to continue his work on short peptides for the treatment of Alzheimer's disease -- as he had originally foreseen.

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