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News Article
Site: http://www.rdmag.com/rss-feeds/all/rss.xml/all

With a combination of theory and clever, meticulous gel-making, scientists from the Department of Energy’s SLAC National Accelerator Laboratory and the University of Toronto have developed a new type of catalyst that’s three times better than the previous record-holder at splitting water into hydrogen and oxygen—the vital first step in making fuels from renewable solar and wind power. The research, published in the journal Science, outlines a potential way to make a future generation of water-splitting catalysts from three abundant metals—iron, cobalt and tungsten—rather than the rare, costly metals that many of today’s catalysts rely on. “The good things about this catalyst are that it’s easy to make, its production can be very easily scaled up without any super-advanced tools, it’s consistent and it’s very robust,” said Aleksandra Vojvodic, a SLAC staff scientist with the SUNCAT Center for Interface Science and Catalysis who led the theoretical side of the work. Scientists have been searching for an efficient way to store electricity generated by solar and wind power so it can be used any time—not just when the sun shines and breezes blow. One way to do that is to use the electrical current to split water molecules into hydrogen and oxygen, and store the hydrogen to use later as fuel. This reaction takes place in several steps, each requiring a catalyst—a substance that promotes chemical reactions without being consumed itself—to move it briskly along. In this case, the scientists focused on a step where oxygen atoms pair up to form a gas that bubbles away, which has been a bottleneck in the process. In previous work, Vojvodic and her SUNCAT colleagues had used theory and computation to look at water-splitting oxide catalysts that contain one or two metals and predict ways to make them more active. For this study, Edward H. Sargent, a professor of electrical and computer engineering at the University of Toronto, asked them to look at the effect of adding tungsten—a heavy, dense metal used in light bulb filaments and radiation shielding—to an iron-cobalt catalyst that worked, but not very efficiently. With the aid of powerful computers at SLAC and elsewhere and state-of-the-art computational tools, the SUNCAT team determined that adding tungsten should dramatically increase the catalyst’s activity—especially if the three metals could be mixed so thoroughly that their atoms were uniformly distributed near the active site of the catalyst, where the reaction takes place, rather than separating into individual clusters as they normally tend to do. “Tungsten is quite a large atom compared to the other two, and when you add a little bit of it, it expands the atomic lattice, and this affects the reaction not only geometrically but also electronically,” Vojvodic said. “We were able to understand, on the atomic scale, why it works, and then that was verified experimentally.” Based on that information, Sargent’s team developed a novel way to distribute the three metals uniformly within the catalyst: They dissolved the metals and other ingredients in a solution and then slowly turned the solution into a gel at room temperature, tweaking the process so the metal atoms did not clump together. The gel was then dried into a white powder whose particles were riddled with tiny pores, increasing the surface area where chemicals can attach and react with each other. In tests, the catalyst was able to generate oxygen gas three times faster, per unit weight, than the previous record-holder, Sargent said, and it also proved to be stable through hundreds of reaction cycles. “It’s a big advance, although there’s still more room to improve,” he said. “And we will need to make catalysts and electrolysis systems even more efficient, cost effective and high intensity in their operation in order to drive down the cost of producing renewable hydrogen fuels to an even more competitive level.” Sargent said the researchers hope to use the same method to develop other three-metal catalysts for splitting water and also for splitting carbon dioxide, a greenhouse gas released by burning fossil fuels, to make renewable fuels and chemical feed stocks. He and five other members of the University of Toronto team have filed for a provisional patent on the technique for preparing the catalyst. “There are a lot of things we further need to understand,” Vojvodic said. “Are there other abundant metals we can test as mixtures in oxides? What are the optimal mixtures of the components? How stable is the catalyst, and how can we scale up its production? It needs to be tested at the device level, really.” Jeffrey C. Grossman, a professor of materials science and engineering at MIT who was not involved in the study, said, “The work impressively highlights the power of tightly coupled computational materials science with advanced experimental techniques, and sets a high bar for such a combined approach. It opens new avenues to speed progress in efficient materials for energy conversion and storage." SLAC research associate Michal Bajdich and Stanford postdoctoral researcher Max García-Melchor also contributed to this work, along with researchers from the DOE’s Brookhaven National Laboratory; East China University of Science & Technology, Tianjin University and the Beijing Synchrotron Radiation Facility in China; and the Canadian Light Source. The research was funded by a number of sources, including the Ontario Research Fund–Research Excellence Program, Natural Sciences and Engineering Research Council of Canada and the CIFAR Bio-Inspired Solar Energy Program, as well as the DOE Office of Science, which funds SUNCAT, and the SLAC Laboratory Directed Research and Development program.


« ABI Research: 6 transformative paradigms driving toward smart, sustainable automotive transportation | Main | First minimal synthetic bacterial cell designed and constructed by scientists at Venter Institute and Synthetic Genomics; 473 genes » Scientists from the Department of Energy’s SLAC National Accelerator Laboratory and the University of Toronto have developed a new type of ternary catalyst for the oxygen evolution reaction (OER) in water-splitting that exhibits a turnover frequency (TOF) that’s more than three-times above the TOF and mass activities of optimized control catalysts and the state-of-art NiFeOOH catalyst. The research, published in the journal Science, outlines a potential way to make a future generation of water-splitting catalysts from three abundant metals—iron (Fe), cobalt (Co) and tungsten (W)—rather than the rare, costly metals on which many of today’s catalysts rely. The gelled FeCoW oxy-hydroxide material exhibits the lowest overpotential (191 mV) reported at 10 mA per square centimeter in alkaline electrolyte. Further, the ternary catalyst showed no evidence of degradation following more than 500 hours of operation. The good things about this catalyst are that it’s easy to make, its production can be very easily scaled up without any super-advanced tools, it’s consistent, and it’s very robust. —Aleksandra Vojvodic, a SLAC staff scientist with the SUNCAT Center for Interface Science and Catalysis who led the theoretical side of the work In previous work, Vojvodic and her SUNCAT colleagues had used theory and computation to look at water-splitting oxide catalysts that contain one or two metals and predict ways to make them more active. For this study, Edward H. Sargent, a professor of electrical and computer engineering at the University of Toronto, asked them to look at the effect of adding tungsten to an iron-cobalt catalyst that worked, but not very efficiently. With the aid of powerful computers at SLAC and elsewhere and state-of-the-art computational tools, the SUNCAT team determined that adding tungsten should significantly increase the catalyst’s activity—especially if the three metals could be mixed so thoroughly that their atoms were uniformly distributed near the active site of the catalyst, where the reaction takes place, rather than separating into individual clusters as they normally tend to do. Based on that information, Sargent’s team developed a novel way to distribute the three metals uniformly within the catalyst: They dissolved the metals and other ingredients in a solution and then slowly turned the solution into a gel at room temperature, tweaking the process so the metal atoms did not clump together. The gel was then dried into a white powder whose particles were riddled with tiny pores, increasing the surface area where chemicals can attach and react with each other. In tests, the catalyst was able to generate oxygen gas three times faster, per unit weight, than the previous record-holder, Sargent said, and it also proved to be stable through hundreds of reaction cycles. Sargent said the researchers hope to use the same method to develop other three-metal catalysts for splitting water and also for splitting carbon dioxide, a greenhouse gas released by burning fossil fuels, to make renewable fuels and chemical feed stocks. He and five other members of the University of Toronto team have filed for a provisional patent on the technique for preparing the catalyst. There are a lot of things we further need to understand. Are there other abundant metals we can test as mixtures in oxides? What are the optimal mixtures of the components? How stable is the catalyst, and how can we scale up its production? It needs to be tested at the device level, really. Jeffrey C. Grossman, a professor of materials science and engineering at MIT who was not involved in the study, said: SLAC research associate Michal Bajdich and Stanford postdoctoral researcher Max García-Melchor also contributed to this work, along with researchers from the DOE’s Brookhaven National Laboratory; East China University of Science & Technology, Tianjin University and the Beijing Synchrotron Radiation Facility in China; and the Canadian Light Source. The research was funded by a number of sources, including the Ontario Research Fund – Research Excellence Program, Natural Sciences and Engineering Research Council of Canada and the CIFAR Bio-Inspired Solar Energy Program, as well as the DOE Office of Science, which funds SUNCAT, and the SLAC Laboratory Directed Research and Development program.


The team has designed the most efficient catalyst for storing energy in chemical form, by splitting water into hydrogen and oxygen, just like plants do during photosynthesis. Oxygen is released harmlessly into the atmosphere, and hydrogen, as H2, can be converted back into energy using hydrogen fuel cells. "Today on a solar farm or a wind farm, storage is typically provided with batteries. But batteries are expensive, and can typically only store a fixed amount of energy," says Sargent. "That's why discovering a more efficient and highly scalable means of storing energy generated by renewables is one of the grand challenges in this field." You may have seen the popular high-school science demonstration where the teacher splits water into its component elements, hydrogen and oxygen, by running electricity through it. Today this requires so much electrical input that it's impractical to store energy this way—too great proportion of the energy generated is lost in the process of storing it. This new catalyst facilitates the oxygen-evolution portion of the chemical reaction, making the conversion from H2O into O2 and H2 more energy-efficient than ever before. The intrinsic efficiency of the new catalyst material is over three times more efficient than the best state-of-the-art catalyst. The new catalyst is made of abundant and low-cost metals tungsten, iron and cobalt, which are much less expensive than state-of-the-art catalysts based on precious metals. It showed no signs of degradation over more than 500 hours of continuous activity, unlike other efficient but short-lived catalysts. Their work was published today in the leading journal Science. "With the aid of theoretical predictions, we became convinced that including tungsten could lead to a better oxygen-evolving catalyst. Unfortunately, prior work did not show how to mix tungsten homogeneously with the active metals such as iron and cobalt," says Dr. Bo Zhang, one of the study's lead authors. "We invented a new way to distribute the catalyst homogenously in a gel, and as a result built a device that works incredibly efficiently and robustly." This research united engineers, chemists, materials scientists, mathematicians, physicists, and computer scientists across three countries. A chief partner in this joint theoretical-experimental study was a leading team of theorists at Stanford University and SLAC National Accelerator Laboratory under the leadership of Dr. Aleksandra Vojvodic. The international collaboration included researchers at East China University of Science & Technology, Tianjin University, Brookhaven National Laboratory, Canadian Light Source and the Beijing Synchrotron Radiation Facility. "The team developed a new materials synthesis strategy to mix multiple metals homogeneously—thereby overcoming the propensity of multi-metal mixtures to separate into distinct phases," said Jeffrey C. Grossman, the Morton and Claire Goulder and Family Professor in Environmental Systems at Massachusetts Institute of Technology. "This work impressively highlights the power of tightly coupled computational materials science with advanced experimental techniques, and sets a high bar for such a combined approach. It opens new avenues to speed progress in efficient materials for energy conversion and storage." "This work demonstrates the utility of using theory to guide the development of improved water-oxidation catalysts for further advances in the field of solar fuels," said Gary Brudvig, a professor in the Department of Chemistry at Yale University and director of the Yale Energy Sciences Institute. "The intensive research by the Sargent group in the University of Toronto led to the discovery of oxy-hydroxide materials that exhibit electrochemically induced oxygen evolution at the lowest overpotential and show no degradation," said University Professor Gabor A. Somorjai of the University of California, Berkeley, a leader in this field. "The authors should be complimented on the combined experimental and theoretical studies that led to this very important finding."


News Article
Site: http://cen.acs.org/news/ln.html

Carbon nanotubes are exceptionally strong and stretchy. To take advantage of these properties, scientists have been trying to make thin sheets from nanotubes that could be used as structural coatings for vehicle or aerospace parts or for protective military and sports gear. But nanotube films’ mechanical properties have so far come nowhere close to those of individual nanotubes. Researchers now report a simple fabrication method to make carbon nanotube films that are five times as strong as those made before—and stronger than films made from Kevlar or carbon fiber (Nano Lett. 2016, DOI: 10.1021/acs.nanolett.5b03863). The new films have densely packed nanotubes, nearly all oriented parallel to each other, which give the films their superior strength, says Jian Nong Wang, a professor of mechanical and power engineering at East China University of Science & Technology. Many groups have tried to align and assemble nanotubes into films, typically by spraying or filtering suspensions of nanotubes onto a surface. But these techniques use short nanotubes and do not align the tubes well, so the films are weak. Wang and his colleagues made nanotubes with a process akin to glass blowing: Using a stream of nitrogen gas, they injected ethanol, with a small amount of ferrocene and thiophene added as catalysts, into a 50-mm-wide horizontal tube placed in furnace at 1,150–1,130 °C. A hollow cylinder with walls made of aligned carbon nanotubes forms in the furnace and emerges from the other end of the tube, driven by the nitrogen. As the tube emerges, the researchers wind the floating carbon nanotube cylinder onto a rotating drum. As the drum spins, the hollow cylinder condenses and flattens into a two-layered, black, carbon nanotube film. Faster winding resulted in better nanotube alignment, the researchers found. Finally, they packed the nanotubes even more densely by pressing the film repeatedly between two rollers. The resulting films had an average strength of 9.6 gigapascals. By comparison, the strength of nanotube films made so far has been around 2 GPa, while that for Kevlar fibers and commercially used carbon fibers is around 3.7 and 7 GPa, respectively. The films are four times as pliable as conventional carbon fibers, and can elongate by 8% on average as opposed to 2% for carbon fibers. Wang says that in addition to their useful mechanical properties, the films have high electrical conductivity, which could make them useful as electrodes for wearable devices and as artificial muscles. Yutaka Matsuo, a professor of chemistry at the University of Tokyo, says that the simplicity of this mechanical winding technique to align nanotubes and make ultra-strong films is notable. The technique also results in pure carbon films, whereas earlier, solution-based methods that press premade nanotubes into films require surfactants that contaminate the films.


News Article | March 24, 1999
Site: www.cnet.com

Apple QuickTime for Java 3.0b4 is out. Apple Remote Install for Mac OS 8.5.x 1.0 has been released. Using this software and Apple Network Assistant, you can install Mac OS 8.5 software on workstations on your network. AppleShare IP Web Services collide with FileMaker Pro 4.1 Web Companion: As noted in Apple TIL article #24854: To avoid the two services from preventing each other from launching, Apple recommends that you give FileMaker Web Companion a different port than the one normally reserved for http services. FileMaker Pro Web Companion and AppleShare IP Web Services both use TCP/IP port 80 by default. Apple recommends you assign port 591 to FileMaker Pro. Although any unused port may work, FileMaker, Inc. has registered port 591 with the Internet Assigned Numbers Authority for use with Web Companion. Solving an Epson install problem (and an interesting tidbit on mounting CDs) Apple TIL article #24857 notes a fix for an Epson printer problem where the installer claims the selected disk is locked and you cannot switch to your hard drive. The problem occurs if you are starting up from the Power Macintosh G3 CD (which contains the USB drivers in the CD Extras folder). The solution is to instead startup (with extensions disabled) from the hard drive. The interesting tidbit here is that if the Mac OS CD is in the drive at startup, it will still mount even though you did not load the Apple CD driver.

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