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An Electrochemical Method Rapidly Produces High-Quality Graphene

ckwu ckwu writes  |  2 days ago

ckwu (2886397) writes "Graphene is easy to acquire in small amounts. But mass production of the strong, conductive, two-dimensional carbon material for commercial uses remains a challenge. Now, scientists have shown they can rapidly produce large quantities of graphene using a bath of inorganic salts and an electric current. Researchers placed two electrodes, one made of platinum and the other of graphite, into an inorganic salt solution, and ran a direct current through them. The graphite electrode shed layers of carbon into the solution, turning more than 75% of the electrode into graphene flakes. In one test using ammonium sulfate as the salt, the researchers were able to produce approximately 16.3 g of graphene in 30 minutes. The researchers see the potential to scale up production to the kilogram scale needed for industrial use."
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Simple Coating Boosts Efficiency of Thin-Film Silicon Solar Cells

ckwu ckwu writes  |  about a month ago

ckwu (2886397) writes "A light-absorbing coating made of metal nanoparticles transforms a low-efficiency solar cell made of an inexpensive form of silicon into one with promising performance. Researchers placed four layers of nanoparticles on top of a 12-micrometer-thick solar cell made of metallurgical silicon, which is one-tenth the cost of the single-crystalline silicon used to make the most efficient solar cells. The resulting device absorbs 98% of the sunlight that hits it and converts nearly 11% of the light into electrical energy. Further research on this coating of metal nanostructures could help improve the performance of other kinds of solar panels without adding much to their cost, the developers say."
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Cleaner Graphene Offers Better Device Performance

ckwu ckwu writes  |  about 2 months ago

ckwu (2886397) writes "Graphene has a dirty little secret. When researchers build electronic devices with it, the standard process they use to move sheets of the delicate, single-atom-thick material into place can lead to contamination or damage that reduces device performance. But now, researchers in Taiwan have developed a simple and elegant way to transfer graphene that keeps the material clean. To test their new transfer method, the researchers made a series of devices, including graphene-based transistors. Electrical charges could move 50% faster through the transistors than in those made with graphene transferred by the conventional method. One researcher suggests the new method could be used to make a type of extremely low-power transistor with interesting quantum effects, called a BiSFET, which ideally needs very clean graphene."
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Device Mines Precious Phosphorus From Sewage

ckwu ckwu writes  |  about 3 months ago

ckwu (2886397) writes "Scientists predict that the scarcity of phosphorus will increase over the next few decades as the growing demand for agricultural fertilizer depletes geologic reserves of the element. Meanwhile, phosphates released from wastewater into natural waterways can cause harmful algal blooms and low-oxygen conditions that can threaten to kill fish. Now a team of researchers has designed a system that could help solve both of these problems. It captures phosphorus from sewage waste and delivers clean water using a combined osmosis-distillation process. The system improves upon current methods by reducing the amounts of chemicals needed to precipitate a phosphorus mineral from the wastewater, thus bringing down the cost of the recovery process."
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Clear Solar Cells Could Help Windows Generate Power

ckwu ckwu writes  |  about 4 months ago

ckwu (2886397) writes "The vast real estate of windows in office buildings and skyscrapers could be a fruitful field for harvesting solar energy—if lightweight solar cells could be made with a high enough conversion efficiency and appealing aesthetics. Now researchers at Oxford University report semitransparent solar cells that might do the trick. The team made solar cells using a perovskite, a class of mineral-like materials that have properties similar to inorganic semiconductors and show sunlight-to-electricity conversion efficiencies of more than 15%. The team deposited a thin film of perovskite onto glass so that the material formed tiny crystalline islands. The islands absorb photons and convert them to electrons, while light striking the empty areas passes through. The result was a semitransparent solar cell with a grayish tint."
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Harvesting Power When Freshwater Meets Salty

ckwu ckwu writes  |  about 5 months ago

ckwu (2886397) writes "As a way to generate renewable electricity, researchers have designed methods that harvest the energy released when fresh and saline water mix, such as when a river meets the sea. One such method is called pressure-retarded osmosis, where two streams of water, one saline and one fresh, meet in a cell divided by a semipermeable membrane. Osmosis drives the freshwater across the membrane to the saltier side, increasing the pressure in the saline solution. The system keeps this salty water pressurized and then releases the pressure to spin a turbine to generate electricity. Now a team at Yale University has created a prototype device that increases the power output of pressure-retarded osmosis by an order of magnitude. At a full-scale facility, the estimated cost of the electricity generated by such a system could be 20 to 30 cents per kWh, approaching the cost of other conventional renewable energy technologies."
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Proteins Help Researchers Build A Flash Memory Device

ckwu ckwu writes  |  about 7 months ago

ckwu (2886397) writes "Researchers in Japan and Taiwan have demonstrated the first working flash memory device made using proteins as scaffolding to build a 3-D nanoparticle structure. Compared to current fabrication techniques, using proteins to arrange nanoparticles could enable the design of smaller memory devices and more complex, multilayer electronics. According to the researchers, their mulitlayer flash memory had twice the capacity of a conventionally made single-layer device."
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Measuring Pressure With The Help Of Static Electricity

ckwu ckwu writes  |  about 8 months ago

ckwu (2886397) writes "A team of scientists would like to exploit the triboelectric effect--the phenomenon behind static electricity--to build useful devices. By harnessing the electron exchange created when certain materials rub together, the researchers developed a simple and inexpensive pressure sensor that doesn’t need an external power source. The devices someday could be incorporated into artificial skin to sense contact or used in computer touch screens."
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Circuit Board Waste Mops Up Toxic Metals

ckwu ckwu writes  |  about 9 months ago

ckwu (2886397) writes "Researchers in Hong Kong have found a beneficial new use for the electronic waste from discarded cell phones, computers, and other gadgets. Ground up into a powder, printed circuit boards from these products could sponge up another type of pollution—toxic heavy metals in water. The researchers processed the nonmetallic fraction of waste circuit boards into a powder and found that it adsorbed metals like copper, lead, and zinc more efficiently than commercially available industrial adsorbents."
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Vehicle Tailpipes Spew a Once Overlooked Pollutant

ckwu ckwu writes  |  about 9 months ago

ckwu (2886397) writes "Vehicle exhaust sends a gaseous soup of small molecules into the air around cities, including acidic chemicals that can cause acid rain or smog. Canadian researchers now report that automobile emissions are a significant source of isocyanic acid, a once overlooked pollutant linked to conditions such as cataracts, rheumatoid arthritis, and hardened arteries. The scientists estimate that urban traffic releases the chemical at levels high enough to possibly trigger health problems in people."
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Low-Cost Micromachine Writes Calligraphy With Atoms

ckwu ckwu writes  |  about 10 months ago

ckwu (2886397) writes "Scientists at Boston University have put together an inexpensive microelectromechanical machine that can direct atoms onto a surface in a controlled manner. The device—which acts as a moving stencil—can lay down such precise, complex patterns that the technique is akin to writing with atoms, the researchers say. They've used the machine to draw rings and infinity symbols out of gold atoms, but the technique should be compatible with almost any material."
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Building New Materials With Light

ckwu ckwu writes  |  about a year ago

ckwu (2886397) writes "Since the 1970s, physicists have used laser beams to trap and study small objects, from cells down to individual atoms. Now, electrical engineers at the University of Southern California have developed a simple optical system that assembles hundreds of nanoparticles into two-dimensional structures using a single laser beam and a silicon photonic crystal. This compact optical trap fits on a small chip and could eventually help researchers make materials for new types of sensors, optical devices, and chemical filters."
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Viruses From Sewage Contaminate Deep Well Water

ckwu ckwu writes  |  about a year ago

ckwu (2886397) writes "Scientists once thought that pathogens could not reach drinking water wells sunk into deep, protected groundwater aquifers. Nevertheless, over the past decade, researchers have identified diarrhea-causing viruses at a handful of deep bedrock well sites in the U.S. and Europe. Now, researchers report where these pathogenic viruses may have originated. The viruses appear to seep from sewer pipes and then swiftly penetrate drinking water wells. Experts recommend that public water systems might need to start testing for viruses on a routine basis."
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