NEWS OF THE WEEK
HELIUM SUPPLY GETS A LIFT INDUSTRIAL GASES: New plant in Qatar will ease shortages for scientific instrument users HE START-UP of a big new helium plant in Qa-
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tar should go a long way to ease shortages of the lighter-than-air chilling gas, which is essential to the operation of many scientific instruments and to the manufacture of fiber-optic cables and semiconductors. The plant, in Qatar’s Las Raffan Industrial City, is the world’s largest helium liquefier, with a production capacity of more than 1.3 billion cu ft per year, according to Air Liquide, which built the purification and chilling equipment. It is operated by Qatar’s RasGas, which separates the helium from natural gas that is drawn from the country’s North Field deposits. The new unit, with annual capacity of 2.1 billion cu ft., makes Qatar the world’s second-largest source of AIR LIQUIDE
This helium liquefier, shown under construction, is now operating in Qatar.
IMPROVING ENERGY CONVERSION MICROSCOPY: Method shows best crystal orientation in nanomaterials
N OBSTACLE to developing low-cost energy conversion devices is understanding why small differences in materials can strongly affect performance. Figuring out the relationship between the structure and function of an electrode material, for example, is especially challenging for nanoparticle aggregates. Researchers have now developed an analytical procedure to scrutinize material structure and function with nanometer resolution across micrometer distances in such aggregates. The technique enables them to design a better electrode for solar energy conversion. The group used transmission electron microscopy (TEM) to image the spatial distribution and orientation of nanocrystals within aggregates. Then, by using a con-
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NAT. MATER.
A TEM method identifies regions of similarly oriented crystallites (colors) in an aggregate, a key step in determining structure-function relations in nanoparticle materials.
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helium. The U.S. cranked out nearly 4.9 billion cu ft of helium last year, of which more than 60% was exported, according to the U.S. Geological Survey. Air Liquide says the start-up marks the next step toward stability in the global helium market, which has been plagued by production glitches and falling supply from traditional sources. Air Liquide has a contract to buy and distribute half of the new Qatari helium. Germany’s Linde and Japan’s Iwatani will buy the remainder of the output. U.S. users welcome the additional supply, but they say helium prices remain too high. “Helium is still $13 per L for us,” says Martha Morton, director of research instrumentation at the University of Nebraska, Lincoln. Last year prices were as high as $22 per L for some users, up from about $5 per L a few years earlier. Morton has already heard from suppliers that prices will rise in 2014. That’s when she plans to refill a repaired 600-MHz nuclear magnetic resonance instrument that was damaged last year when she couldn’t get the helium needed to keep it operating. Just how much of an increase Morton will have to pay hinges on the potential shutdown in October of Cliffside Field, a U.S. government reserve in Texas that accounted for one-third of the world’s helium output last year. Congress is now considering legislation to keep the field operating for a few more years until reserves run out.—MARC REISCH
ducting atomic force microscopy method, they correlated the TEM information with the pathways that electrons follow as they move through the material. They used the combo method to probe electron transport in various nanoparticle-based iron oxide electrodes. The electron-transport proficiency of this cheap material makes it useful for generating hydrogen via light-driven water splitting. Although the electrodes they studied were similar, some worked well, while others did not. The key finding of the team, which includes Scott C. Warren of the University of North Carolina, Chapel Hill, is that the relative orientation of adjacent nanoparticles greatly affects charge transport. A small orientation mismatch is alright, but a large mismatch results in electrical barriers that block current flow between adjacent grains. The upshot is that by identifying “winning” crystal orientations and tailoring the preparation method to favor them throughout the electrode, the group made a device that achieves a record-setting photocurrent for this class of materials (Nat. Mater. 2013, DOI: 10.1038/nmat3684). “These results represent an important step forward in developing nanostructured materials for next-generation energy conversion devices,” says solar-fuel specialist Roel van de Krol of Technical University of Berlin. Boston College chemist Dunwei Wang adds that the study helps explain why some nanostructures function better than others. “This work will be of value to photoelectrochemistry studies in general,” he adds.—MITCH JACOBY
JULY 15, 2013
