New, inexpensive production materials boost promise of hydrogen fuel

http://feeds.feedburner.com/~r/sciencedaily/top_news/top_science/~4/HeD-Y2-DBAA

Generating electricity is not the only way to turn sunlight into energy we can use on demand. The sun can also drive reactions to create chemical fuels, such as hydrogen, that can in turn power cars, trucks and trains.The trouble with solar fuel production is the cost of producing the sun-capturing semiconductors and the catalysts to generate fuel. The most efficient materials are far too expensive to produce fuel at a price that can compete with gasoline.”In order to make commercially viable devices for solar fuel production, the material and the processing costs should be reduced significantly while achieving a high solar-to-fuel conversion efficiency,” says Kyoung-Shin Choi, a chemistry professor at the University of Wisconsin-Madison.In a study published last week in the journal Science, Choi and postdoctoral researcher Tae Woo Kim combined cheap, oxide-based materials to split water into hydrogen and oxygen gases using solar energy with a solar-to-hydrogen conversion efficiency of 1.7 percent, the highest reported for any oxide-based photoelectrode system.Choi created solar cells from bismuth vanadate using electrodeposition — the same process employed to make gold-plated jewelry or surface-coat car bodies — to boost the compound’s surface area to a remarkable 32 square meters for each gram.”Without fancy equipment, high temperature or high pressure, we made a nanoporous semiconductor of very tiny particles that have a high surface area,” says Choi, whose work is supported by the National Science Foundation. “More surface area means more contact area with water, and, therefore, more efficient water splitting.”Bismuth vanadate needs a hand in speeding the reaction that produces fuel, and that’s where the paired catalysts come in.While there are many research groups working on the development of photoelectric semiconductors, and many working on the development of water-splitting catalysts, according to Choi, the semiconductor-catalyst junction gets relatively little attention.”The problem is, in the end you have to put them together,” she says. “Even if you have the best semiconductor in the world and the best catalyst in the world, their overall efficiency can be limited by the semiconductor-catalyst interface.”Choi and Kim exploited a pair of cheap and somewhat flawed catalysts — iron oxide and nickel oxide — by stacking them on the bismuth vanadate to take advantage of their relative strengths.”Since no one catalyst can make a good interface with both the semiconductor and the water that is our reactant, we choose to split that work into two parts,” Choi says. “The iron oxide makes a good junction with bismuth vanadate, and the nickel oxide makes a good catalytic interface with water. So we use them together.”The dual-layer catalyst design enabled simultaneous optimization of semiconductor-catalyst junction and catalyst-water junction.”Combining this cheap catalyst duo with our nanoporous high surface area semiconductor electrode resulted in the construction of an inexpensive all oxide-based photoelectrode system with a record high efficiency,” Choi says.She expects the basic work done to prove the efficiency enhancement by nanoporous bismuth vanadate electrode and dual catalyst layers will provide labs around the world with fodder for leaps forward.”Other researchers studying different types of semiconductors or different types of catalysts can start to use this approach to identify which combinations of materials can be even more efficient,” says Choi, whose lab is already tweaking their design. “Which some engineering, the efficiency we achieved could be further improved very fast.”Story Source:The above story is based on materials provided by University of Wisconsin-Madison. The original article was written by Chris Barncard. Note: Materials may be edited for content and length.


Read More: New, inexpensive production materials boost promise of hydrogen fuel

#Agriculture, #Alternative-Medicine, #Bismuth, #Cancer, #Gen, #Health, #Material, #National, #University, #Wisconsin, #World

Vibration energy the secret to self-powered electronics

http://feeds.feedburner.com/~r/sciencedaily/living_well/~4/E7t3rhq8DS8

A multi-university team of engineers has developed what could be a promising solution for charging smartphone batteries on the go — without the need for an electrical cord.Incorporated directly into a cell phone housing, the team’s nanogenerator could harvest and convert vibration energy from a surface, such as the passenger seat of a moving vehicle, into power for the phone. “We believe this development could be a new solution for creating self-charged personal electronics,” says Xudong Wang, an assistant professor of materials science and engineering at the University of Wisconsin-Madison.Wang, his Ph.D. student Yanchao Mao and collaborators from Sun Yat-sen University in China, and the University of Minnesota Duluth described their device, a mesoporous piezoelectric nanogenerator, in the January 27, 2014, issue of the journal Advanced Energy Materials.The nanogenerator takes advantage of a common piezoelectric polymer material called polyvinylidene fluoride, or PVDF. Piezoelectric materials can generate electricity from a mechanical force; conversely, they also can generate a mechanical strain from an applied electrical field.Rather than relying on a strain or an electrical field, the researchers incorporated zinc oxide nanoparticles into a PVDF thin film to trigger formation of the piezoelectric phase that enables it to harvest vibration energy. Then, they etched the nanoparticles off the film; the resulting interconnected pores — called “mesopores” because of their size — cause the otherwise stiff material to behave somewhat like a sponge.That sponge-like material is key to harvesting vibration energy. “The softer the material, the more sensitive it is to small vibrations,” says Wang.The nanogenerator itself includes thin electrode sheets on the front and back of the mesoporous polymer film, and the researchers can attach this soft, flexible film seamlessly to flat, rough or curvy surfaces, including human skin. In the case of a cell phone, it uses the phone’s own weight to enhance its displacement and amplify its electrical output.The nanogenerator could become an integrated part of an electronic device — for example, as its back panel or housing — and automatically harvest energy from ambient vibrations to power the device directly.Wang says the simplicity of his team’s design and fabrication process could scale well to larger manufacturing settings. “We can create tunable mechanical properties in the film,” he says. “And also important is the design of the device. Because we can realize this structure, phone-powering cases or self-powered sensor systems might become possible.”Story Source:The above story is based on materials provided by University of Wisconsin-Madison. …


Read More: Vibration energy the secret to self-powered electronics

#Advancedenergy, #Agriculture, #Alzheimer, #Development, #Health, #Journal, #Material, #Materials, #Minnesota, #Piezoelectric, #University

Video: Asbestos Exposure, Should You Be Concerned?

Video: Asbestos Exposure, Should You Be Concerned?












Asbestos exposure has been linked to the development of serious respiratory diseases and cancers, including mesothelioma, lung cancer, asbestosis and other conditions. Asbestos was an extremely common building material for many...

Read More: Video: Asbestos Exposure, Should You Be Concerned?

#Asbestos, #Concentration, #Concern, #Conditions, #Exposure, #Family, #Health, #Material, #Mesothelioma, #Related, #Respiratory

Graphene"s love affair with water: Water filters allow precise and fast sieving of salts and organic molecules

http://feeds.feedburner.com/~r/sciencedaily/top_news/top_science/~4/DtCM2na7OMo

Graphene has proven itself as a wonder material with a vast range of unique properties. Among the least-known marvels of graphene is its strange love affair with water.Graphene is hydrophobic — it repels water — but narrow capillaries made from graphene vigorously suck in water allowing its rapid permeation, if the water layer is only one atom thick — that is, as thin as graphene itself.This bizarre property has attracted intense academic and industrial interest with intent to develop new water filtration and desalination technologies.One-atom-wide graphene capillaries can now be made easily and cheaply by piling layers of graphene oxide — a derivative of graphene — on top of each other. The resulting multilayer stacks (laminates) have a structure similar to nacre (mother of pearl), which makes them also mechanically strong.Two years ago, University of Manchester researchers discovered that thin membranes made from such laminates were impermeable to all gases and vapours, except for water. This means that even helium, the hardest gas to block off, cannot pass through the membranes whereas water vapour went through with no resistance.Now the same team led by Dr Rahul Nair and Prof Andre Geim has tested how good the graphene membranes are as filters for liquid water. The results appear in the latest issue (Feb 14, 2014) of Science.The researchers report that, if immersed in water, the laminates become slightly swollen but still allow ultrafast flow of not one but two monolayers of water.Small salts with a size of less than nine Angstroms can flow along but larger ions or molecules are blocked. Ten Angstroms is equivalent to a billionth of a metre.The graphene filters have an astonishingly accurate mesh that allows them to distinguish between atomic species that are only a few percent different in size.On top of this ultraprecise separation, it is also ultrafast. Those ions that can go through do so with such a speed as if the graphene membranes were an ordinary coffee filter.The latter effect is due to a property that the Manchester scientists call “ion sponging.” Their graphene capillaries suck up small ions as powerful hoovers leading to internal concentrations that can be hundreds of times higher than in external salty solutions.Dr Nair said: “The water filtration is as fast and as precise as one could possibly hope for such narrow capillaries. Now we want to control the graphene mesh size and reduce it below nine Angstroms to filter out even the smallest salts like in seawater. Our work shows that it is possible.”Dr Irina Grigorieva, a co-author of the study, added: “Our ultimate goal is to make a filter device that allows a glass of drinkable water made from seawater after a few minutes of hand pumping. We are not there yet but this is no longer science fiction.”Story Source:The above story is based on materials provided by University of Manchester. …


Read More: Graphene"s love affair with water: Water filters allow precise and fast sieving of salts and organic molecules

#Bizarre, #Cancer, #Dre, #Industrial, #Marvels, #Material, #Permeation, #Properties, #Result, #Science, #Story, #Unique

Plastic shopping bags make a fine diesel fuel

http://feeds.feedburner.com/~r/sciencedaily/top_news/top_science/~4/IQ3CtGqK5Qg

Plastic shopping bags, an abundant source of litter on land and at sea, can be converted into diesel, natural gas and other useful petroleum products, researchers report.The conversion produces significantly more energy than it requires and results in transportation fuels — diesel, for example — that can be blended with existing ultra-low-sulfur diesels and biodiesels. Other products, such as natural gas, naphtha (a solvent), gasoline, waxes and lubricating oils such as engine oil and hydraulic oil also can be obtained from shopping bags.A report of the new study appears in the journal Fuel Processing Technology.There are other advantages to the approach, which involves heating the bags in an oxygen-free chamber, a process called pyrolysis, said Brajendra Kumar Sharma, a senior research scientist at the Illinois Sustainable Technology Center who led the research. The ISTC is a division of the Prairie Research Institute at the University of Illinois.”You can get only 50 to 55 percent fuel from the distillation of petroleum crude oil,” Sharma said. “But since this plastic is made from petroleum in the first place, we can recover almost 80 percent fuel from it through distillation.”Americans throw away about 100 billion plastic shopping bags each year, according to the Worldwatch Institute. The U.S. Environmental Protection Agency reports that only about 13 percent are recycled. The rest of the bags end up in landfills or escape to the wild, blowing across the landscape and entering waterways.Plastic bags make up a sizeable portion of the plastic debris in giant ocean garbage patches that are killing wildlife and littering beaches. Plastic bags “have been detected as far north and south as the poles,” the researchers wrote.”Over a period of time, this material starts breaking into tiny pieces, and is ingested along with plankton by aquatic animals,” Sharma said. Fish, birds, ocean mammals and other creatures have been found with a lot of plastic particles in their guts.Whole shopping bags also threaten wildlife, Sharma said.”Turtles, for example, think that the plastic grocery bags are jellyfish and they try to eat them,” he said. Other creatures become entangled in the bags.Previous studies have used pyrolysis to convert plastic bags into crude oil. …


Read More: Plastic shopping bags make a fine diesel fuel

#Agriculture, #Alzheimer, #Cancer, #Environmental, #Health, #Institute, #Istc, #King, #Material, #Research, #Science, #Sharma

Urban bees using plastic to build hives

http://feeds.feedburner.com/~r/sciencedaily/plants_animals/agriculture_and_food/~4/iHKrppOguOM

Once the snow melts, Canada’s bee population will be back in business — pollinating, making honey and keeping busy doing bee things. For at least two urban bee species, that means making nests out of plastic waste.A new study by a University of Guelph graduate and a U of G scientist reveals that some bees use bits of plastic bags and plastic building materials to construct their nests. The research was published recently in the journal Ecosphere.It’s an important discovery because it shows bees’ resourcefulness and flexibility in adapting to a human-dominated world, says lead author Scott MacIvor, a doctoral student at York University and a 2008 U of G graduate.”Plastic waste pervades the global landscape,” said MacIvor. Although researchers have shown adverse impacts of the material on species and the ecosystem, few scientists have observed insects adapting to a plastic-rich environment, he said.”We found two solitary bee species using plastic in place of natural nest building materials, which suggests innovative use of common urban materials.Figuring out that the bees were using plastics in place of natural materials took some detective work by U of G’s Andrew Moore, supervisor of analytical microscopy at Laboratory Services.Moore analyzed a grey “goo” that MacIvor discovered in the nests of one kind of bee, Megachile campanulae, which uses plant resins to build its nests,”Scott thought it might be chewing gum originally,” Moore said. His team uses a scanning electron microscope to take highly detailed pictures of items, x-ray microanalysis to determine the elements in the sample and infrared microscopy to identify polymers. They can distinguish the finest detail on the surface of an animal hair.Turns out that M. campanulae was occasionally replacing plant resins with polyurethane-based exterior building sealant, such as caulking, in its brood cells–created in a nest to rear larva.The researchers also discovered another kind of bee, Megachile rotundata, an alfalfa leafcutter, was using pieces of polyethylene-based plastic bags to construct its brood cells. The glossy plastic replaced almost one-quarter of the cut leaves normally used to build each cell.Markings showed that the bees chewed the plastic differently than they did leaves, suggesting that the insects had not incidentally collected plastic. Nor were leaves hard to find for the bees in the study.”The plastic materials had been gathered by the bees, and then worked — chewed up and spit out like gum — to form something new that they could use,” Moore said.In both cases, larvae successfully developed from the plastic-lined nests. In fact, the bees emerged parasite-free, suggesting plastic nests may physically impede parasites, the study said.The nests containing plastic were among more than 200 artificial nest boxes monitored by MacIvor as part of a large-scale investigation of the ecology of urban bees and wasps, a project involving numerous citizen scientists.The nest boxes are located in Toronto and the surrounding region in backyards, community gardens and parks and on green roofs. …


Read More: Urban bees using plastic to build hives

#Bees, #Common, #Health, #Material, #Megachile, #Moore, #Plastic, #Research, #Team, #Toronto