Putting sunshine in the tank

Working with the Universities of East Anglia, York and Nottingham and using nanotechnology 100,000 times smaller than the thickness of a human hair, the researchers are working on harnessing the vast energy of the Sun to produce clean fuel.

The scientists are presenting their research at the Royal Society's annual Summer Science Exhibition which opens
today [5 July 2011].

Members of the consortium at UEA have already found a way to produce hydrogen from water. A revolutionary future use of this technology could be to make the fuel for hydrogen-powered cars, rather than making it from fossil fuel.

Now the scientists are aiming to use the same technology to create alternatives for other fuels and feedstock chemicals, including turning methane into liquid methanol and carbon dioxide into carbon monoxide.

The sun's potential is vast – just one hour of sunlight is equivalent to the amount of energy used over the world
in an entire year – yet no one has yet tapped into its immense power to make fuels.

Professor Wendy Flavell, from The University of Manchester's Photon Science Institute, and her colleagues are working to create a solar-nano device using 'quantum dots' – tiny clusters of semiconducting material which absorb sunlight.

When sunlight is absorbed, carriers of electric current are created. Together with catalyst molecules grafted to the surfaces of the dots, these create the new fuel – for example hydrogen can be produced from water. Professor
Flavell said: "Our sun provides far more energy than we will ever need, but we use it really inefficiently.

"To make better use of the fantastic resource we have in our Sun, we need to find out how to create solar fuel that can be stored and shipped to where it is needed and used on demand.

"Most hydrogen so far is obtained from fossil fuels, which are of course not going to last for ever, so it is important to get energy from renewable sources."One of the key questions is: 'what do we do when the sun goes down, what happens at night?' If we can store the energy harnessed from the sun during the day then we will have supplies ready to use when the sun is not shining.

"This is a first step in taking the vast power of the sun and using it to provide the world's fuel needs."

At the exhibition, Professor Flavell and her team will be displaying an interactive world map which will show
children and other visitors just how much energy the Sun provides.

There will also be a chance to see the quantum dots at work, and show how, simply by changing the size of the dots, the colour of light they absorb or give out can be changed.

A solar cell that produces hydrogen directly from the electricity generated will also be on display and there will
be a chance to race solar-powered and hydrogen-powered model racing cars.

Professor Chris Pickett of the University of East Anglia said "Creating catalytic devices which harvest light energy using quantum dots, or photovoltaic materials to drive the formation of synthetic fuels from water or carbon dioxide can be viewed as artificial photosynthesis.

"Globally, chemists, physicists and materials scientists are coming together to work on artificial photosynthesis to get to a stage where we can viably make clean, green fuels"

Professor Robin Perutz of the University of York said: "This is the most challenging scientific project I have ever
been involved in, but it will be the most rewarding if we can bring it off. It's no use sitting back and hoping that someone else will work out how to harness the Sun's energy. This technology could revolutionise our energy usage in the coming decades."

Provided by University of Manchester (news : web)

'Ubiquitous element strategy' for overcoming potential deficiencies of rare elements

Japanese scientists report on a unique ‘ubiquitous element strategy’ to overcome the ‘rare-element crisis’ that was triggered by increasing demand for such elements as lithium, used in batteries, and dysprosium for Ne-Fe-B permanent magnets.

‘Ubiquitous element strategy’ for overcoming potential deficiencies of rare elements in the synthesis of industrially important electronic, thermionic, and structural materials.

Japanese scientists report on a unique ‘ubiquitous element strategy’ for synthesizing industrially important electronic, thermionic, and structural materials using naturally abundant elements. This strategy aims to overcome the ‘rare-element crisis’ that was triggered by increasing demand for such elements as lithium, used in batteries, and dysprosium for Ne-Fe-B permanent magnets.

In the review article published in the journal Science and Technology of Advanced Materials, scientists from Tokyo Institute of Technology describe their research on the synthesis and applications of oxide materials based on the 20–30 most abundant elements including Si, Al, Ca, Na, and Mg. The key to this strategy is an in-depth knowledge of the role of elements in the physical properties of materials—knowledge available from research on the science and technology of nanometer-sized materials.

Research covered in this paper includes:

The conversion of ceramic 12CaO•7Al2O3 (C12A7)—interconnected, positively charged nano-cages—into a chemically and thermally stable transparent conductor which undergoes a metal-superconductor transition at 0.2 K. C12A7 has a wide bandgap of >7 eV and a low work function of 2.4 eV. The authors describe the synthesis, properties, and applications—light-emitting, electron field emitters, and nonvolatile memories—of C12A7 based on their own research.

The generation of ionized oxygen is important in the electronics industry for applications including the production of silicon diode layers on semiconductors. Conventional methods rely on the catalytic action of Pt—a metal in scarce supply. Here, the researchers describe the production of large quantities of atomic oxygen by incandescent heating of 2-mm-diameter tube of yttria-doped zirconia—a solid oxide electrolyte that conducts oxygen ions. This method of generating atomic oxygen is more efficient, highly selective in the types of ions generated, and enables lower temperature oxidation of silicon compared with thermal oxidation.

In another example of the ‘ubiquitous element strategy’ the authors describe the effect of phase transitions on the controlled fracture in mullite ceramics (3Al2O3•2SiO2), which is crucial for impact-resistant armor and bumper shields for spacecraft. The researchers found that mullite exhibited superior protection as Whipple bumper shields compared to conventional aluminum alloys “tested for the impact by an aluminum alloy flyer at 5.5 km/s”.

Other materials discussed include SrTiO3/TiO2, exhibiting a fivefold higher Seebeck effect compared with bulk material; the pulsed laser deposition of flat MgO(111) films on Al2O3(0001) substrates and of atomically flat MgO(111) films on YSZ(111) substrates with NiO(111) buffer layers.

More information: Hideo Hosono et al., “New functionalities in abundant element oxides: ubiquitous element strategy”, Science and Technology of Advanced Materials 12 (2011) p. 034303. http://dx.doi.org/ … /12/3/034303

Provided by National Institute for Materials Science

Extremely rapid water: Scientists decipher a protein-bound water chain

Researchers from the RUB-Department of Biophysics of Prof. Dr. Klaus Gerwert have succeeded in providing evidence that a protein is capable of creating a water molecule chain for a few milliseconds for the directed proton transfer. The combination of vibrational spectroscopy and biomolecular simulations enabled the elucidation of the proton pump mechanism of a cell-membrane protein in atomic detail. The researchers demonstrated that protein-bound water molecules play a decisive role in the function. Their results were selected for the Early Edition of PNAS.

Specific proteins can transport protons from one side (uptake side) of the cell membrane to the other side (release side). This is a central process in biological energy conversion. In past editions of Nature and Angewandte Chemie the researchers from the Department of Biophysics had already published their observations that in the ground state the protein-bound water molecules at the release side are optimally arranged for the release of protons. "As with dominos, the protein initiates movement of the protons which finally leads to their release", explains Prof. Gerwert. Just how the protein re-attains its initial state in order to start another pumping cycle remained to be clarified. New protons must be acquired at the uptake side of the protein to substitute the released protons. The researchers in Bochum discovered that a chain of only three water molecules is formed for just a few thousandths of a second to transfer the protons into the interior of the protein.

The protein kills two birds with one stone. The water molecules are disordered during the release phase, which prevents the protons from being transported in the false direction. Only during the uptake phase, they are correctly aligned and can conduct protons. These results are the solution to the riddle as to why proton transfer only functions in one direction at the uptake side and why the protein is capable of effective and directional pumping. "This paper, together with the two preceding publications, now constitutes a trilogy which supplies a full explanation for the proton pumping cycle at an atomic level", summarizes Prof. Gerwert.

The researchers combined experimental physics with theoretical chemistry to be able to observe the processes with a high spatial and temporal resolution at a nano-level. Steffen Wolf simulated the structural changes within the protein using biomolecular computer simulations (molecular dynamics simulations). Erik Freier subsequently verified the effects experimentally using a special kind of vibrational spectroscopy developed by Prof. Gerwert (time-resolved step-scan FTIR spectroscopy). "This interdisciplinary interplay, which showed that the individual components of the protein are as precisely synchronized as the gears of a machine, was the key to success", says Prof. Gerwert.

The protein arranges the three water molecules so skillfully that they transport the protons using the physico-chemical Grotthuss mechanism. In the 1950s, the Nobel Prize winner Manfred Eigen elucidated this mechanism to explain extremely rapid, non-directional proton transport in water. Surprisingly enough, the publications of the RUB researchers now reveal that amino acids coupled with protein-bound water molecules can give this extremely rapid transportation a direction of movement. Prof. Gerwert's team was thus able to augment Manfred Eigen's results and apply them to protein research.

The group of research scientists in Bochum primarily works with the membrane protein bacteriorhodopsin, which is used by certain bacteria to carry out an archaic form of photosynthesis. Bacteriorhodopsin creates a proton concentration gradient by transporting protons from the interior to the exterior of a cell. Other proteins use this gradient to produce ATP, the universal cellular fuel. It is important that the proton transport has a specific direction and that spontaneous backflow of protons is prevented to ensure that light energy can be effectively used.

More information: References:

Freier, E., Wolf, S., Gerwert, K. Proton transfer via a transient linear water-molecule chain in a membrane protein. PNAS, early edition, doi: 10.1073/pnas.1104735108 (2011)

Wolf, S., Freier, E., Potschies, M., Hofmann, E., Gerwert, K. Directional Proton Transfer in Membrane Proteins Achieved through Protonated Protein-Bound Water Molecules: A Proton Diode. Angew. Chem. Int. Ed., 49, 6889-6893 (2010)

Garczarek, F., Gerwert, K.: „Functional waters in intraprotein proton transfer monitored by FTIR difference spectroscopy". Nature, 439, 109-112 (2006)

Provided by Ruhr-University Bochum

Green chemistry: Getting nickel back

In Southeast Asia, palm oil is used both as an ingredient for cooking and a raw material for biodiesel production. To stabilize the oil against decomposition, it has to be hydrogenated in the presence of a nickel catalyst that modifies its physical and chemical properties. Eventually, the nickel catalyst becomes contaminated by residual fats, oils and other chemicals, rendering it unusable.

Qizhen Yang and co-workers at the A*STAR Singapore Institute of Manufacturing Technology (SIMTech) have now shown that these spent nickel catalysts could be recovered in a manner that is not only safe and environmentally friendly, but which could also generate considerable profits for recycling companies.

“There is increasing concern over the sustainability of new recycling technologies and processes,” explains Yang. “Traditionally spent catalysts, which have a commercial value, would be used as raw materials for nickel smelting. What attracted the recyclers for implementing this new process is the fact that the recovery of pure nickel would deliver more added market value, and that the process would be greener and more socially responsible, making it more sustainable.”

Many methods of recycling nickel catalysts have been attempted, including chemical leaching, roasting, electrolysis and bioleaching with microorganisms. The SIMTech researchers propose a combination of technologies: the catalyst is first roasted to remove residual impurities, producing an ash containing large amounts of nickel and nickel oxide; the ash is then subject to acid leaching, acid separation, nickel enrichment and finally deposition of the metal from solution.

These steps constitute a ‘closed-loop’ process whereby many of the byproducts, including the acid, plating solutions and dilution water, can be reused to minimize waste. On weighing the costs of materials, equipment and labor against the potential market conditions, the researchers showed that a small nickel recovery plant of this sort would be economically viable if the price of nickel is more than $12.57 per kilogram—a very realistic target.

The researchers also analyzed the carbon footprint of the operation and showed that its greenhouse gas emissions could be minimized through the use of efficient processing techniques and by sourcing green electricity. Finally, given that the process would create jobs and produce no toxic waste, it could certainly be a socially sustainable solution.

“Our industrial partners are now implementing the process in a new nickel recovery facility,” says Yang. “They are using our sustainability assessment results to understand what factors affect the sustainability of their processes and to help them justify the decisions they make in recovering nickel from waste.”

More information: Yang, Q.Z., et al. Sustainable recovery of nickel from spent hydrogenation catalyst: economics, emissions and wastes assessment. Journal of Cleaner Production 19, 365–375 (2011).

Provided by Agency for Science, Technology and Research (A*STAR)

Promising fire retardant results when clay nanofiller has space

If materials scientists accompanied their research with theme songs, a team from the National Institute of Standards and Technology and the University of Maryland might be tempted to choose the garage punk song "Don't Crowd Me"* as the anthem for the promising, but still experimental nanocomposite fire retardants they are studying.

That's because the collaborators have demonstrated that the more widely and uniformly dispersed nanoscale plates of clay are in a polymer, the more fire protection the nanocomposite material provides.

Writing in the journal Polymer,** the team reports that in tests of five specimens—each with the same amount of the nanoscale filler (5 percent by weight)—the sample with the most widely dispersed clay plates was far more resistant to igniting and burning than the specimen in which the plates mostly clustered in crowds. In fact, when the two were exposed to the same amount of heat for the same length of time, the sample with the best clay dispersion degraded far more slowly. Additionally, its reduction in mass was about a third less.

In the NIST/UMD experiments, the material of interest was a polymer—a type of polystyrene, used in packaging, insulation, plastic cutlery and many other products—imbued with nanometer scale plates of montmorillonite, a type of clay with a sandwich-like molecular structure. The combination can create a material with unique properties or properties superior to those achievable by each component—clay or polymer—on its own.

Polymer-montmorillonite nanocomposites have attracted much research and commercial interest over the last decade or so. Studies have suggested that how the clay plates disperse, stack or clump in polymers dictates the properties of the resultant material. However, the evidence—especially when it comes to the flammability properties of the nanocomposites—has been somewhat muddy.

Led by NIST guest researcher Takashi Kashiwagi, the NIST-UMD team subjected their clay-dispersion-varying samples to an exhaustive battery of characterization methods and flammability tests. Affording views from the nanoscopic to the microscopic, the array of measurements and flammability tests yielded a complete picture of how the nanoscale clay plates dispersed in the polymer and how the resultant material responded when exposed to an influx of heat.

The researchers found that with better dispersion, clay plates entangle more easily when exposed to heat, thereby forming a network structure that is less likely to crack and leading to fewer gaps in the material. The result, they say, is a heat shield that slows the rate of degradation and reduces flammability. The NIST team, led by Rick Davis, is now exploring other approaches to reduce flammability, including the use of advanced materials and novel coating techniques.

More information:
* Keith Kessler, "Don't Crowd Me."
** M. Liu, X. Zhang, M. Zammarano, J.W. Gilman, R.D. Davis and T. Kashiwagi. Effect of Montmorillonite dispersion on flammability properties of poly(styrene-co-acrylonitrile) nanocomposites. Polymer. Vol. 52, Issue 14, June 22, 2011.

Provided by National Institute of Standards and Technology (news : web)