NanoComputer

Cheaper clean-energy technologies could be made possible thanks to a new discovery. Research team members led by Raymond Schaak, a professor of chemistry at Penn State, have found that an important chemical reaction that generates hydrogen from water is effectively triggered — or catalyzed — by a nanoparticle made of nickel and phosphorus, two inexpensive elements that are abundant on Earth. The results of the research will be published in the Journal of the American Chemical Society. Schaak explained that the purpose of this nanoparticle is to help produce hydrogen from water — a process that is important for many energy-production technologies including fuel cells and solar cells. “Water is an ideal fuel, because it is cheap and abundant, but we need to be able to extract hydrogen from it,” Schaak said. Hydrogen has a high energy density and is a great energy carrier, Schaak explained, but it requires energy to produce. To make its production practical, scientists have been hunting for a way to trigger the required chemical reactions with an inexpensive catalyst. Platinum works, but it is expensive and relatively rare, so Schaak and his team have been searching for alternative materials.

“There were some predictions that nickel phosphide might be a good candidate, and we already had been working with nickel phosphide nanoparticles for several years,” Schaak said. “It turns out that nanoparticles of nickel phosphide are indeed active for producing hydrogen and are comparable to the best known alternatives to platinum.”

Source: http://news.psu.edu/

Throughout decades of research on solar cells, one formula has been considered an absolute limit to the efficiency of such devices in converting sunlight into electricity: Called the Shockley-Queisser efficiency limit, it posits that the ultimate conversion efficiency can never exceed 34 percent for a single optimized semiconductor junction. Now, researchers at the Massachusetts Institute of Technology – MIT – have shown that there is a way to blow past that limit as easily as today’s jet fighters zoom through the sound barrier — which was also once seen as an ultimate limit. Their work appears this week in a report in the journal Science.

singlet exciton fission. (An exciton is the excited state of a molecule after absorbing energy from a photon.)
While today’s commercial solar panels typically have an efficiency of at most 25 percent, a silicon solar cell harnessing singlet fission should make it feasible to achieve efficiency of more than 30 percent, Baldo says — a huge leap in a field typically marked by slow, incremental progress. In solar cell research, he notes, people are striving “for an increase of a tenth of a percent.”

Solar panel efficiencies can also be improved by stacking different solar cells together, but combining solar cells is expensive with conventional solar-cell materials. The new technology instead promises to work as an inexpensive coating on solar cells.

Source: http://web.mit.edu/

Genes from the family of bacteria that produce vinegar, Kombucha tea and nata de coco have become stars in a project that would turn algae into solar-powered factories for producing the “wonder material” nanocellulose. Reports on advances in getting those genes to produce fully functional nanocellulose were part of the 245th National Meeting & Exposition of the American Chemical Society (ACS), the world’s largest scientific society.

“If we can complete the final steps, we will have accomplished one of the most important potential agricultural transformations ever,” said R. Malcolm Brown, Jr., Ph.D. “We will have plants that produce nanocellulose abundantly and inexpensively. It can become the raw material for sustainable production of biofuels and many other products. While producing nanocellulose, the algae will absorb carbon dioxide, the main greenhouse gas linked to global warming.”

Most cellulose consists of wood fibers and cell wall remains. Very few living organisms can actually synthesize and secrete cellulose in its native nanostructure form of microfibrils. At this level, nanometer-scale fibrils are very hydrophilic and look like jelly. A nanometer is one-millionth the thickness of a U.S. dime. Nevertheless, cellulose shares the unique properties of other nanometer-sized materials — properties much different from large quantities of the same material. Nanocellulose-based materials can be stronger than steel and stiffer than Kevlar. Great strength, light weight and other advantages has fostered interest in using it in everything from lightweight armor and ballistic glass to wound dressings and scaffolds for growing replacement organs for transplantation.

Source: http://www.eurekalert.org/

Professor Dong Rip Kim from Hangyang University – Korea – has succeeded in fabricating peel-and-stick thin film solar cells (TFSCs) with the collaboration of Stanford team led by Professor Xiaolin Zheng. This method makes possible the overcoming of hardships related to working with traditional solar cells, namely the lack of handling, high manufacturing cost, and limited flexibility while maintaining performance. Kim is currently in charge of the Hanyang University Nanotechnology for Energy Conversion Lab. His research interests are solar cells, energy conversion devices using nanomaterials, flexible electronics, nanoelectronics, and nanosensors. Among Kim’s recent publications are “Peel-and-Stick: Fabricating Thin Film Solar Cell on Universal Substrates” in the journal of Scientific Reports, “Shrinking and Growing: Grain Boundary Density Reduction for Efficient Polysilicon Thin-Film Solar Cells” in the journal of Nano Letters, and “Thermal Conductivity in Porous Silicon Nanowire Arrays” in the journal of Nanoscale Research Letters.

“I will continue to focus on creating highly efficient but low costing energy conversion devices with nanotechnology,” Kim said. Moreover, his future research will focus on applying his method in other types of solar cells and in other applications.

Source: http://www.hanyang.ac.kr/

Scientists at Aalto University, Finland and Fraunhofer ISE, Germany report an efficiency of 18.7% for black silicon solar cells, the highest efficiency reported so far for a black silicon solar cell.
The researchers were able to apply a boron diffusion to create a pn-junction, maintaining the excellent optical properties of the black silicon structure. By applying atomic layer deposited Al203, an effective passivation of the nanostructured surfaces was achieved. The previous efficiency record of 18.2% was held by the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) using thermal oxidation as a passivating layer.

“The quantum efficiency measurements reveal that the nanostructured front surface is of a high electrical quality comparable to a pyramidal textured surface”, says Assistant Professor Hele Savin of Aalto University.
Routes for improving the cell efficiency are already identified, and efficiencies clearly above 20% should be within reach.
Source: http://www.aalto.fi/

A novel fabrication technique developed by the University of Connecticut – UConn could provide the breakthrough technology scientists have been looking for to vastly improve today’s solar energy systems.The technology would be a vast improvement over the silicon solar panels. Even the best silicon panels collect only about 20 percent of available solar radiation, and separate mechanisms are needed to convert the stored energy to usable electricity for the commercial power grid. The panels’ limited efficiency and expensive development costs have been two of the biggest barriers to the widespread adoption of solar power as a practical replacement for traditional fossil fuels.

But while nanosized antennas have shown promise in theory, scientists have lacked the technology required to construct and test them. The fabrication process is immensely challenging. The nano-antennas – known as “rectennas” because of their ability to both absorb and rectify solar energy from alternating current to direct current – must be capable of operating at the speed of visible light and be built in such a way that their core pair of electrodes is a mere 1 or 2 nanometers apart, a distance of approximately one millionth of a millimeter. Nanosized antenna arrays are theoretically capable of harvesting more than 70 percent of the sun’s electromagnetic radiation and simultaneously converting it into usable electric power.
The potential breakthrough lies in a novel fabrication process called selective area atomic layer deposition (ALD) that was developed by Willis, an associate professor of chemical and biomolecular engineering at UConn. Willis developed the ALD process while teaching at the University of Delaware, and patented the technique in 2011.

Source: http://today.uconn.edu/

New technology could help power portable devices like satellite phones and radios. University at Buffalo researchers demonstrate that super-small particles of silicon react with water to produce hydrogen almost instantaneously. In a series of experiments, the scientists created spherical silicon particles about 10 nanometers in diameter. When combined with water, these particles reacted to form silicic acid (a nontoxic byproduct) and hydrogen — a potential source of energy for fuel cells. The reaction didn’t require any light, heat or electricity, and also created hydrogen about 150 times faster than similar reactions using silicon particles 100 nanometers wide, and 1,000 times faster than bulk silicon, according to the study.

“When it comes to splitting water to produce hydrogen, nanosized silicon may be better than more obvious choices that people have studied for a while, such as aluminum,” said researcher Mark T. Swihart, UB professor of chemical and biological engineering and director of the university’s Strategic Strength in Integrated Nanostructured Systems. The scientists were able to verify that the hydrogen they made was relatively pure by testing it successfully in a small fuel cell that powered a fan.
Source: http://www.buffalo.edu/

Working at Berkeley Lab’s Advanced Light Source (ALS), a premier source of X-ray and ultraviolet light beams for research, an international team of scientists found that for highly efficient polymer/organic photovoltaic cells, size matters. The amount of solar energy lighting up Earth’s land mass every year is nearly 3,000 times the total amount of annual human energy use. But to compete with energy from fossil fuels, photovoltaic devices must convert sunlight to electricity with a certain measure of efficiency. For polymer-based organic photovoltaic cells, which are far less expensive to manufacture than silicon-based solar cells, scientists have long believed that the key to high efficiencies rests in the purity of the polymer/organic cell’s two domains – acceptor and donor. Now, however, an alternate and possibly easier route forward has been shown.

Molecular view of polymer/fullerene solar film showing an interface between acceptor and donor domains. Red dots are PC71BM molecules and blue lines represent PTB7 chains. Excitons are shown as yellow dots, purple dots are electrons and green dots represent holes.

“We’ve shown that impure domains if made sufficiently small can also lead to improved performances in polymer-based organic photovoltaic cells,” says Harald Ade, a physicist at North Carolina State University, who led this research. “There seems to be a happy medium, a sweet-spot of sorts, between purity and domain size that should be much easier to achieve than ultra-high purity.”
Source: http://newscenter.lbl.gov

Researchers from North Carolina State University have created flower-like structures out of germanium sulfide (GeS) – a semiconductor material – that have extremely thin petals with an enormous surface area. The GeS flower holds promise for next-generation energy storage devices and solar cells.

“Creating these GeS nanoflowers is exciting because it gives us a huge surface area in a small amount of space,” says Dr. Linyou Cao, an assistant professor of materials science and engineering at NC State and co-author of a paper on the research. “This could significantly increase the capacity of lithium-ion batteries, for instance, since the thinner structure with larger surface area can hold more lithium ions. By the same token, this GeS flower structure could lead to increased capacity for supercapacitors, which are also used for energy storage.”

Source: http://news.ncsu.edu/releases/wms-cao-flower/

It’s a clever bit of natural engineering that inspired imitation from a UW-Madison electrical and computer engineer, who has found a way to mimic the passive heliotropism seen in sunflowers for use in the next crop of solar power systems.
Unlike other “active” solar systems that track the sun‘s position with GPS and reposition panels with motors, electrical and computer engineering professor Hongrui Jiang’s concept leverages the properties of unique materials in concert to create a passive method of re-orienting solar panels in the direction of the most direct sunlight.

His design, published Aug. 1 in Advanced Functional Materials and recently highlighted in Nature, employs a combination of liquid crystalline elastomer (LCE), which goes through a phase change and contracts in the presence of heat, with carbon nanotubes, which can absorb a wide range of light wavelengths.
Source: http://www.news.wisc.edu/20967

Researching for clean energy generation,  scientists at Harvard University have demonstrated  that  a solid-oxide fuel cell (SOFC) that converts hydrogen into electricity,  can also store electrochemical energy like a battery. This fuel cell can continue to produce power for a short time after its fuel has run out.

“Unmanned aerial vehicles, for instance, would really benefit from this,” says lead author Quentin Van Overmeere, a postdoctoral fellow at the Harvard School of Engineering and Applied Sciences (SEAS). “When it’s impossible to refuel in the field, an extra boost of stored energy could extend the device’s life span significantly.” The finding, which appeared online in the journal Nano Letters, will be most important for small-scale, portable energy applications, where a very compact and lightweight power supply is essential and the fuel supply may be interrupted.

Source: http://news.harvard.edu/gazette/story/2012/06/fuel-cell-keeps-going-after-hydrogen-runs-out/

By tweaking the smallest of parts, a trio of  engineers is hoping to dramatically increase the amount of sunlight that solar cells convert into electricity. The researchers from the University at Buffalo, Army Research Laboratory and Air Force Office of Scientific Research have developed a new, nanomaterials-based technology that has the potential to increase the efficiency of photovoltaic cells up to 45 percent.

Specifically, the scientists have shown that embedding charged quantum dots into solar cells can improve electrical output by enabling the cells to harvest infrared light, and by increasing the lifetime of photoelectrons. The technology can be applied to many different photovoltaic structures.

A new company the researchers founded, OPtoElectronic Nanodevices LLC. (OPEN LLC), is commercializing this technology.

Source: http://www.buffalo.edu/news/13138