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February 5th, 2013

Other materials stories that may be of interest

Published on February 5th, 2013 | Edited by: Peter Wray

What an active field!

Oxygen tolerance of an in silico-designed bioinspired hydrogen-evolving catalyst in water

(PNAS) Certain bacterial enzymes, the diiron hydrogenases, have turnover numbers for hydrogen production from water as large as 104/s. Their much smaller common active site, composed of earth-abundant materials, has a structure that is an attractive starting point for the design of a practical catalyst for electrocatalytic or solar photocatalytic hydrogen production from water. In earlier work, our group has reported the computational design of [FeFe]P/FeS2, a hydrogenase-inspired catalyst/electrode complex, which is efficient and stable throughout the production cycle. However, the diiron hydrogenases are highly sensitive to ambient oxygen by a mechanism not yet understood in detail. An issue critical for practical use of [FeFe]P/FeS2 is whether this catalyst/electrode complex is tolerant to the ambient oxygen. We report demonstration by ab initio simulations that the complex is indeed tolerant to dissolved oxygen over timescales long enough for practical application, reducing it efficiently. This promising hydrogen-producing catalyst, composed of earth-abundant materials and with a diffusion-limited rate in acidified water, is efficient as well as oxygen tolerant.

America’s Growing Minerals Deficit

(ProEdgeWire/WSJ) After every election, there’s a mad scramble in Washington over the must-make-it-happen agenda for the newly inaugurated president and Congress. There are welcome signs from the White House’s own Material Genome Initiative that securing America’s access to critical metals and minerals will be high on the list. A good thing, too. Jobs and capital increasingly flow to countries that command the resources to power modern manufacturing, and American manufacturing is more dependent on metals and minerals access than ever before. Yet there is no country on the planet where it takes longer to get a permit for domestic mining. Among other consequences of this red tape, there are now 19 strategic metals and minerals for which the U.S. is currently 100 percent import-dependent-and for 11 of them a single country, China, is among the top three providers.

Researchers developing nanosensor to detect CO2

Researchers at the Universities of Toronto and St. Francis Xavier, Canada, are developing an affordable, energy efficient and ultrasensitive nanosensor that has the potential to detect even one molecule of carbon dioxide. Current sensors used to detect CO2 at surface sites are either very expensive or they use a lot of energy. And they’re not as accurate as they could be. Improving the accuracy of measuring and monitoring stored CO2 is seen as key to winning public acceptance of carbon capture and storage as a greenhouse gas mitigation method. With funding from Carbon Management Canada, Harry Ruda of the Centre for Nanotechnology at UT and David Risk of StFX are working on single-nanowire transistors that should have unprecedented sensitivity for detecting CO2 emissions. CMC, a national network that supports game-changing research to reduce CO2 emissions in the fossil energy industry as well as from other large stationary emitters, is providing Ruda and his team $350,000 over three years. The grant is part of CMC’s third round of funding which saw the network award $3.75 million to Canadian researchers working on eight different projects. Risk is also using a CMC grant to work on marrying specialized sensor-housings, called forced diffusion chambers, with fiber-optic CO2 sensors.

Flat boron by the numbers: Rice researchers calculate what it would take to make new 2D material

It would be a terrible thing if laboratories striving to grow graphene from carbon atoms kept winding up with big pesky diamonds. “That would be trouble, cleaning out the diamonds so you could do some real work,” says Rice University theoretical physicist Boris Yakobson, chuckling at the absurd image. Yet something like that keeps happening to experimentalists working to grow two-dimensional boron. Boron atoms have a strong preference to clump into 3D shapes rather than assemble into pristine single-atom sheets, like carbon does when it becomes graphene. And boron clumps aren’t nearly as sparkly. Yakobson and his Rice colleagues have made progress toward 2D boron through theoretical work that suggests the most practical ways to make the material and put it to work. Earlier calculations by the group indicated 2D born would conduct electricity better than graphene. Through first-principle calculations of the interaction of boron atoms with various substrates, the team came up with several possible paths experimentalists may take toward 2D boron. Yakobson feels the work may point the way toward other useful 2D materials.

Diamond defects shrink MRI to the nanoscale

(Nature) Diamond-based quantum devices can now make nuclear magnetic resonance measurements on the molecular scale. Work by two independent groups will make it easier to find out the structure of single biological molecules such as proteins without destroying or freezing them. Nuclear magnetic resonance (NMR) and its close cousin magnetic resonance imaging (MRI) give information about a sample’s structure by detecting the weak magnetic forces in certain atomic nuclei, such as hydrogen. They work by detecting how molecules collectively resonate—like guitar strings that vibrate together—with electromagnetic waves of specific wavelengths. The techniques provide information about the structure of samples without damaging them, which is particularly important if the sample is a human body. But to some researchers, whole bodies are less interesting than the molecules that they are made up of. “I want to push NMR and MRI to the molecular level,” says Friedemann Reinhard, a physicist at the University of Stuttgart in Germany. His team is one of two that have used NMR to detect hydrogen atoms in samples measuring just a few nanometres across. The second team was led by Daniel Rugar, manager of nanoscale studies at IBM’s Almaden Research Center in San Jose, Calif. Both studies are published in Science.

A safer next-gen battery is used with solar panels for the first time

(GigaOm) But the next generation of lithium ion batteries are promising to be safer, and a few of them are already starting to be used in real-world situations in the power grid, electric vehicles and gadgets… So what makes Seeo’s batteries safer? It largely involves improvements to the electrolyte, or the medium that shuttles lithium ions back and forth between the cathode and the anode to charge and discharge the battery. Traditional lithium-ion battery electrolytes are mostly made of liquids, while Seeo is using a solid dry polymer based electrolyte, which feels like plastic to the touch. The polymer is non-flammable and when combined with using lithium foil as the anode, the battery can be ultra light weight and also have a high energy density, or amount of energy that can be stored per a given weight. If traditional lithium ion batteries are overcharged they can have a margin of error in the danger zone of about 20 percent above the max voltage of the battery, explained Zarem. In contrast, Seeo batteries have a margin of error of 100 percent over the voltage. The batteries also won’t burst into flames if something penetrates it (for example, during a car crash).


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