Nanostructured Electrodes from a Molybdenum Disulfide-Carbon Composite may provide Practical Fast-Charging Batteries


Fast Charge batteries vid47065

Electrodes are critical parts of every battery architecture — charge too fast, and you can decrease the charge-discharge cycle life or damage the battery so it won’t charge anymore. Scientists have built a new design and chemistry for electrodes. Their design involves advanced, nanostructured electrodes containing molybdenum disulfide and carbon nanofibers (Advanced Energy Materials, “Pseudocapacitive charge storage in thick composite MoS2 nanocrystal-based electrodes”). These composite materials have internal atomic-scale pathways. These paths are for both fast ion and electron transport, allowing for fast charging.

Fast Charge batteries vid47065

Battery electrodes made of a molybdenum disulfide nanocrystal composite have internal pathways to allow lithium ions to move quickly through the electrode, speeding up the rate that the battery can charge. The key features in the structure that enable the flow of the lithium ions are the small, 20-40 nanometer, diameter of the nanocrystals (in contrast, human hairs are about 100,000 nanometers in diameter) coupled with the porosity and planar lamellar pathways shown in the electron micrograph. (Image: Sarah Tolbert, University of California, Los Angeles)

 

The new battery electrodes provide several benefits. The electrodes allow fast charging. They also have stable charge/discharge behavior, so the batteries last longer. These electrodes show promise for practical electrical energy storage systems.
New battery electrodes based on nanostructured molybdenum disulfide combine the ability to charge in seconds with high capacity and long cycle life. Typical lithium-ion batteries charge slowly due to slow diffusion of lithium ions within the solid electrode.
Another type of energy storage device (a.k.a., pseudocapacitors), which has similarities to the capacitors found in common electrical circuits, speeds up the charging process by using reactions at or near the electrode surface, thus avoiding slow solid-state diffusion pathways.
Nanostructured electrodes allow the creation of large surface areas so that the battery can work more like a pseudocapacitor. In this work at the University of California, Los Angeles, scientists made nanostructured electrodes from a molybdenum disulfide-carbon composite.
Many electrodes are based on metal oxides, but because sulfur more weakly interacts with lithium than oxygen, lithium atoms can move more freely in the metal sulfide than the metal oxide. The result is a battery electrode that shows high capacity and very fast charging times.
The novel electrodes deliver specific capacities of 90 mAh/g (about half that of a typical lithium-ion battery cathode) charging in less than 20 seconds, and retain over 80 percent of their original capacity after 3,000 charge/discharge cycles. Capacities of greater than 180 mAh/g (similar to cathodes in conventional lithium-ion cells) are achieved at slower charging rates.
The results have exciting implications for the development of fast-charging energy storage systems that could replace traditional lithium-ion batteries.
Source: U.S. Department of Energy, Office of Science

 

Ceramic membranes separate tiny organic molecules with a molar mass of 200 Dalton


ceramicmembrCeramic membranes by the Fraunhofer Institute for Ceramic Technologies and Systems IKTS. Credit: Fraunhofer IKTS

Water is vital – therefore, waste water has to be cleaned as efficiently as possible. Ceramic membranes make this possible. Researchers from the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Hermsdorf, Germany were able to significantly reduce the separation limits of these membranes and to reliably filter off dissolved organic molecules with a molar mass of only 200 Dalton. Even industrial sewage water can thus be cleaned efficiently.

Anyone who has dragged himself along a sunny coastal path at the height of summer with too little in his bag knows all too well: without water, we cannot make it too long. Water is one of the foundations of life. In industry, water is a must, as well: in many production processes, it serves as a solvent, detergent, to cool or to transfer heat. As more and more water is consumed, waste water has to be treated and reused. Ceramic membranes offer a good way to do this: since they are separated mechanically – similar to a coffee filter – they are particularly energy-efficient. However, this method previously came to an end when a molecular size of 450 Daltons was reached: smaller molecules could not be separated with . According to experts, it was even considered impossible to go below this limit.

Molecules as small as 200 Daltons can be separated

Dr. Ingolf Voigt, Dr.-Ing. Hannes Richter and Dipl.-Chem. Petra Puhlfuerss from the Fraunhofer IKTS have achieved the impossible. “With our ceramic membranes, we have achieved, for the first time, a molecular separation limit of 200 Daltons – and, thereby, a whole new quality,” says Voigt, Deputy Institute Director of the IKTS and Site Manager in Hermsdorf.

ceramicmembrWatch a Short Video

 

But how did the researchers manage to do this? On the way to making the impossible possible, it was first necessary to overcome various obstacles. The first was in the production of the itself: if such small molecules were to be separated reliably, a membrane was needed that had pores smaller than the molecules which were to be separated. In addition, all of the pores had to be as similar in size as possible, since a single larger opening is sufficient to allow molecules to slip through. The challenge was therefore to produce pores which were as small as possible, with all of them having more or less the same size. “We achieved these results by refining sol-gel technology,” says Richter, Head of Department at the IKTS. The second hurdle was to make such membrane layers defect-free over larger surfaces. The Fraunhofer researchers have succeeded in doing this, as well. “Whereas only a few square centimeters of surface are usually coated, we equipped a pilot system with a membrane area of 234 square meters, which means that our membrane is several magnitudes larger,” explains Puhlfuerss, scientist at the IKTS.

Transfer from the laboratory into practice

Commissioned by Shell, the pilot system was built by the company Andreas Junghans – Anlagenbau und Edelstahlbearbeitung GmbH & Co. KG in Frankenberg, Germany and is located in Alberta, Canada. There the system has been successfully purifying since 2016, which is used for the extraction of oil from oil sand. The researchers are currently planning an initial production facility with a membrane area of more than 5,000 square meters.

The innovative ceramic membranes also offer advantages in industrial production processes: they can be used to purify partial currents directly in the process as well as to guide the cleaned water in the cycle, which saves water and energy.

For the development of the ceramic nanofiltration membrane, Dr. Ingolf Voigt, Dr.-Ing. Hannes Richter and Dipl.-Chem. Petra Puhlfuerss received this year’s Joseph von Fraunhofer Prize. The jury justifies the award by mentioning, among other things, “the first-ever realization for filtration applications within this material class.”

Explore further: New, water-based, recyclable membrane filters all types of nanoparticles

 

EV Maker Fisker Tweets More Details About the Upcoming EMotion Electric Sedan – Use of Hybrid Graphene Batteries Yet 2 Come ~ A Challenge for Tesla?


 

Fisker-EMotion-TwitterSays graphene batteries won’t go into production yet

Henrik Fisker, initiator of a project to start an electric car company relying on a long-range battery that uses graphene, recently stated that the company’s upcoming electric luxury sedan will use lithium-ion batteries to power the car rather than the graphene battery technology currently under development for future models.

EMotion is slated to officially debut on August 17, 2017 with a tentative release in 2019. Pricing starts at $129,900, placing it in the same range as Tesla Model S. It will be interesting to see at what point, if at all, graphene-based batteries will be used in these cars.

Fisker says the EMotion will still offer 400+ miles of electric range. Quick charging can return 100 miles of range to the battery in nine minutes using what the company calls UltraCharger technology.

“Very proud of what we are creating!” Fisker said via Twitter recently.

His EMotion EV features dramatic suicide-butterfly doors and its sporty wheels are made from aluminum and carbon fiber. Other high-tech features include a lidar sensor recessed in the front bumper to be used for autonomous driving.

Fisker-EV-graphene-battery-img_assist-400x225The EMotion also boasts a Lipik Electrochromic glass roof and rear passenger windows, which can be tinted by the touch of a button.

EMotion is slated to officially debut on August 17, 2017 with a tentative release in 2019. Pricing starts at $129,900, placing it in the same range as Tesla Model S. Pre-orders are open now at www.fiskerinc.com.

Graphene 2017 ImageForArticle_4454(1)See Our Related Article:

The Coming Battery Revolution: Graphene and Batteries 

 

 

The Coming Battery Revolution: Graphene and Batteries 



Graphene 2017 ImageForArticle_4454(1)Graphene and Batteries 

** Re-Posted from earlier article from Graphene Info

Graphene , a sheet of carbon atoms bound together in a honeycomb lattice pattern, is hugely recognized as a “wonder material” due to the myriad of astonishing attributes it holds. It is a potent conductor of electrical and thermal energy, extremely lightweight chemically inert, and flexible with a large surface area. It is also considered eco-friendly and sustainable, with unlimited possibilities for numerous applications.

In the field of batteries, conventional battery electrode materials (and prospective ones) are significantly improved when enhanced with graphene. Graphene can make batteries that are light, durable and suitable for high capacity energy storage, as well as shorten charging times.

It will extend the battery’s life-time, which is negatively linked to the amount of carbon that is coated on the material or added to electrodes to achieve conductivity, and graphene adds conductivity without requiring the amounts of carbon that are used in conventional batteries.

Graphene can improve such battery attributes as energy density and form in various ways. Li-ion batteries can be enhanced by introducing graphene to the battery’s anode and capitalizing on the material’s conductivity and large surface area traits to achieve morphological optimization and performance.

It has also been discovered that creating hybrid materials can also be useful for achieving battery enhancement. A hybrid of Vanadium Oxide (VO2) and graphene, for example, can be used on Li-ion cathodes and grant quick charge and discharge as well as large charge cycle durability.

In this case, VO2 offers high energy capacity but poor electrical conductivity, which can be solved by using graphene as a sort of a structural “backbone” on which to attach VO2 – creating a hybrid material that has both heightened capacity and excellent conductivity.

Another example is LFP ( Lithium Iron Phosphate) batteries, that is a kind of rechargeable Li-ion battery. It has a lower energy density than other Li-ion batteries but a higher power density (an indicator of of the rate at which energy can be supplied by the battery).

Enhancing LFP cathodes with graphene allowed the batteries to be lightweight, charge much faster than Li-ion batteries and have a greater capacity than conventional LFP batteries.

 

In addition to revolutionizing the battery market, combined use of graphene batteries and supercapacitors could yield amazing results, like the noted concept of improving the electric car’s driving range and efficiency.

Battery Basics

Batteries serve as a mobile source of power, allowing electricity-operated devices to work without being directly plugged into an outlet.
While many types of batteries exist, the basic concept by which they function remains similar: one or more electrochemical cells convert stored chemical energy into electrical energy. A battery is usually made of a metal or plastic casing, containing a positive terminal (an anode), a negative terminal (a cathode) and electrolytes that allow ions to move between them.

A separator (a permeable polymeric membrane) creates a barrier between the anode and cathode to prevent electrical short circuits while also allowing the transport of ionic charge carriers that are needed to close the circuit during the passage of current.

Finally, a collector is used to conduct the charge outside the battery, through the connected device.



Eneloop battery design

When the circuit between the two terminals is completed, the battery produces electricity through a series of reactions. The anode experiences an oxidation reaction in which two or more ions from the electrolyte combine with the anode to produce a compound, releasing electrons. At the same time, the cathode goes through a reduction reaction in which the cathode substance, ions and free electrons combine into compounds. Simply put, the anode reaction produces electrons while the reaction in the cathode absorbs them and from that process electricity is produced.

The battery will continue to produce electricity until electrodes run out of necessary substance for creation of reactions.

Battery types and characteristics

Batteries are divided into two main types: primary and secondary. Primary batteries (disposable), are used once and rendered useless as the electrode materials in them irreversibly change during charging. Common examples are the zinc-carbon battery as well as the alkaline battery used in toys, flashlights and a multitude of portable devices.

Secondary batteries (rechargeable), can be discharged and recharged multiple times as the original composition of the electrodes is able to regain functionality. Examples include lead-acid batteries used in vehicles and lithium-ion batteries used for portable electronics.

Batteries come in various shapes and sizes for countless different purposes. Different kinds of batteries display varied advantages and disadvantages.


Nickel-Cadmium (NiCd)
batteries are relatively low in energy density and are used where long life, high discharge rate and economical price are key. They can be found in video cameras and power tools, among other uses. NiCd batteries contain toxic metals and are environmentally unfriendly.


Nickel-Metal hydride
batteries have a higher energy density than NiCd ones, but also a shorter cycle-life. Applications include mobile phones and laptops.


Lead-Acid
batteries are heavy and play an important role in large power applications, where weight is not of the essence but economic price is. They are prevalent in uses like hospital equipment and emergency lighting.

Lithium-Ion (Li-ion) batteries are used where high-energy and minimal weight are important, but the technology is fragile and a protection circuit is required to assure safety. Applications include cell phones and various kinds of computers.


Lithium Ion Polymer (Li-ion polymer)
batteries are mostly found in mobile phones. They are lightweight and enjoy a slimmer form than that of Li-ion batteries.
They are also usually safer and have longer lives. However, they seem to be less prevalent since Li-ion batteries are cheaper to manufacture and have higher energy density.

Batteries and supercapacitors

While there are certain types of batteries that are able to store a large amount of energy, they are very large, heavy and release energy slowly.

Capacitors, on the other hand, are able to charge and discharge quickly but hold much less energy than a battery.

The use of graphene in this area, though, presents exciting new possibilities for energy storage, with high charge and discharge rates and even economical affordability.
Graphene-improved performance thereby blurs the conventional line of distinction between supercapacitors and batteries.

Li-Polymer battery vs Supercapacitor structure


Commercial Graphene-enhanced battery products

Graphene-based batteries have exciting potential and while they are not commercially available yet, R&D is intensive and will hopefully yield results in the future.

In November 2016, Huawei unveiled a new graphene-enhanced Li-Ion battery that can remain functional at higher temperature (60° degrees as opposed to the existing 50° limit) and offers a longer operation time – double than what can be achieved with previous batteries.

To achieve this breakthrough, Huawei incorporated several new technologies – including an anti-decomposition additives in the electrolyte, chemically stabilized single crystal cathodes – and graphene to facilitate heat dissipation. Huawei says that the graphene reduces the battery’s operating temperature by 5 degrees.



In June 2014, US based Vorbeck Materials
announced the Vor-Power strap, a lightweight flexible power source that can be attached to any existing bag strap to enable a mobile charging station (via 2 USB and one micro USB ports). the product weighs 450 grams, provides 7,200 mAh and is probably the world’s first graphene-enhanced battery.

In May 2014, American company Angstron Materials rolled out several new graphene products. The products, said to become available roughly around the end of 2014, include a line of graphene-enhanced anode materials for Lithium-ion batteries. The battery materials were named “NANO GCA” and are supposed to result in a high capacity anode, capable of supporting hundreds of charge/discharge cycles by combining high capacity silicon with mechanically reinforcing and conductive graphene.

Developments are also made in the field of graphene batteries for electric vehicles. Henrik Fisker, who announced its new EV project that will sport a graphene-enhanced battery, unveiled in November 2016 what is hoped to be a competitor to Tesla. Called EMotion, the electric sports car will reportedly achieve a 161 mph (259 kmh) top speed and a 400-mile electric range.

Graphene Nanochem and Sync R&D’s October 2014
plan to co-develop graphene-enhanced Li-ion batteries for electric buses, under the Electric Bus 1 Malaysia program, is another example.

In August 2014, Tesla suggested the development of a “new battery technology” that will almost double the capacity for their Model S electric car. It is unofficial but reasonable to assume graphene involvement in this battery.

UK based Perpetuus Carbon Group and OXIS Energy agreed in June 2014 to co-develop graphene-based electrodes for Lithium-Sulphur batteries, which will offer improved energy density and possibly enable electric cars to drive a much longer distance on a single battery charge.

Another interesting venture, announced in September 2014 by US based Graphene 3D Labs, regards plans to print 3D graphene batteries. These graphene-based batteries can potentially outperform current commercial batteries as well as be tailored to various shapes and sizes.

Other prominent companies which declared intentions to develop and commercialize graphene-enhanced battery products are: Grafoid, SiNode together with AZ Electronic Materials, XG Sciences, Graphene Batteries together with CVD Equipment and CalBattery.

Fisker-EMotion-TwitterRead More: The Fisker EV Sedan “EMotion”

EV Maker Fisker and Tesla Rival Plans to Use Graphene in Batteries to Extend Range – Improve Consumer Experience

Cheap Catalysts turn Sunlight and Carbon Dioxide into Fuel – Sustainable & Abundant Energy


Photosynthesis NREL iStock-503352336_16x9Thanks to a new catalyst, sunlight has been converted into chemical energy with a record 13.4% efficiency.

Scientists have long dreamed of mimicking photosynthesis, by using the energy in sunlight to knit together hydrocarbon fuels from carbon dioxide (CO2) and water. Now, a cheap new chemical catalyst has carried out part of that process with record efficiency, using electricity from a solar cell to split CO2 into energy-rich carbon monoxide (CO) and oxygen. The conversion isn’t yet efficient enough to compete with fossil fuels like gasoline. But it could one day lead to methods for making essentially unlimited amounts of liquid fuels from sunlight, water, and CO2, the chief culprit in global warming.

A bright idea

A new catalyst made from copper and tin oxides uses electric current from a solar cell to split water (H2O) and carbon dioxide (CO2), creating energy-rich carbon monoxide (CO) that can be further refined into liquid fuels.

 

NREL I downloadThe new work is “a very nice result,” says John Turner, a renewable fuels expert at the National Renewable Energy Laboratory in Golden, Colorado.

The transformation begins when CO2 is broken down into oxygen and CO, the latter of which can be combined with hydrogen to make a variety of hydrocarbon fuels. Adding four hydrogen atoms, for example, creates methanol, a liquid fuel that can power cars. Over the last 2 decades, researchers have discovered a number of catalysts that enable that first step and split CO2 when the gas is bubbled up through water in the presence of an electric current. One of the best studied is a cheap, plentiful mix of copper and oxygen called copper oxide. The trouble is that the catalyst splits more water than it does CO2, making molecular hydrogen (H2), a less energy-rich compound, says Michael Graetzel, a chemist at the Swiss Federal Institute of Technology in Lausanne, whose group has long studied these CO2-splitting catalysts.

Last year, Marcel Schreier, one of Graetzel’s graduate students, was looking into the details of how copper oxide catalysts work. He put a layer of them on a tin oxide–based electrode, which fed electrons to a beaker containing water and dissolved CO2. Instead of splitting mostly water—like the copper oxide catalyst—the new catalyst generated almost pure CO. “It was a discovery made by serendipity,” Graetzel says.

The tin, Graetzel adds, seems to deactivate the catalytic hot spots that help split the water. As a result, almost all the electric current went into making the more desirable CO. Armed with the new insight, Graetzel’s team sought to speed up the catalyst’s work. To do so, they remade their electrode from copper oxide nanowires, which have a high surface area for carrying out the CO2-breaking reaction, and topped them with a single atom-thick layer of tin. As Graetzel’s team reports this week in Nature Energy, the strategy worked, converting 90% of the CO2 molecules into CO, with hydrogen and other byproducts making up the rest. They also hooked their setup to a solar cell and showed that a record 13.4% of the energy in the captured sunlight was converted into the CO’s chemical bonds. That’s far better than plants, which store energy with about 1% efficiency, and even tops recent hybrid approaches that combine catalysts with microbes to generate fuel.

Nate Lewis, a chemist at the California Institute of Technology in Pasadena, says the new result comes on the heels of other recent improvements that use different catalysts to turn CO2 into fuels. “Together, they show we’re making progress,” Lewis says. But he also cautions that current efforts to turn CO2into fuel remain squarely in the realm of basic research, because they can’t generate fuel at a price anywhere near to that of refining oil.

Still, exploding supplies of renewable electricity now occasionally generate more power than the grid can handle. So scientists are looking for a viable way to store the excess electricity. That’s likely to drive further progress in storing energy in chemical fuels, Graetzel says.

 

Posted in: DOI: 10.1126/science.aan6935

New “Instantly Rechargeable” Flow Battery could Dramatically Change EV Market


IN BRIEF

Purdue researchers have developed a flow battery that would allow electric cars to be recharged instantly at stations like conventional cars are. The technology is clean, safe, and cheap.

GO WITH THE FLOW

Purdue researchers have developed technology for an “instantly rechargeable” battery that is affordable, environmentally friendly, and safe. Currently, electric vehicles need charging ports in convenient locations to be viable, but this battery technology would allow drivers of hybrid and electric vehicles to charge up much like drivers of conventional cars refill quickly and easily at gas stations.

This breakthrough would not only speed the switch to electric vehicles by making them more convenient to drive, but also reduce the amount of new supportive infrastructure needed for electric cars dramatically. 

Purdue University professors John Cushman and Eric Nauman teamed up with doctoral student Mike Mueterthies to co-found Ifbattery LLC (IF-battery) for commercializing and developing the technology.
Image Credit: John Cushman/Purdue

The new model is a flow battery, which does not require an electric charging station to be recharged. Instead, all the users have to do is replace the battery’s fluid electrolytes — rather like filling up a tank. 

This battery’s fluids from used batteries, all clean, inexpensive, and safe, could be collected and recharged at any solar, wind, or hydroelectric plant. Electric cars using this technology would arrive at the refueling station, deposit spent fluids for recharging, and “fill up” like a traditional car might.

CLEANER, FASTER BATTERY TECHNOLOGY

This flow battery system is unique because, unlike other versions of the flow battery, this one lacks the membranes which are both costly and vulnerable to fouling. 

“Membrane fouling can limit the number of recharge cycles and is a known contributor to many battery fires,” Cushman said in a press release. “Ifbattery’s components are safe enough to be stored in a family home, are stable enough to meet major production and distribution requirements, and are cost effective.”

What’s My Range? Electric Vehicles (Click to View Full Infographic)

Transitioning existing infrastructure to accommodate cars using these batteries would be far simpler than designing and building a host of new charging stations — which is Tesla’s current strategy. Existing pumps could even be used for these battery chemicals, which are very safe.

“Electric and hybrid vehicle sales are growing worldwide and the popularity of companies like Tesla is incredible, but there continues to be strong challenges for industry and consumers of electric or hybrid cars,” Cushman said in the press release. “The biggest challenge for industry is to extend the life of a battery’s charge and the infrastructure needed to actually charge the vehicle.”

When can we expect to see these batteries in use? 
The biggest hurdle isn’t the materials, which are cheap and plentiful, but person power. The researchers still need more financing to complete research and development to put the batteries into mass production.

 To overcome this problem, they’re working to publicize the innovation in the hopes of drawing interest from investors.

References: Purdue, Purdue Research Park

Does the Future of Drone Technology Lie in these Tiny Genetically Modified Dragonflies? Behind the Scenes Video


dragonflEye_129415

CREDIT: Courtesy Draper

Researchers have turned dragonflies into controllable micro-drones to help track wildlife populations and pollinate flowers. But should we fear weaponized insects?

Engineers at Draper, a technology research company in Cambridge, and neuroscientists at Howard Hughes Medical Institute at Janelia Research Center outfitted dragonflies with miniature “backpack guidance systems” to control the insects.

Joe Register, a biomedical engineer at Draper and senior researcher on the DragonflEye program, says the team outfitted only a few insects with the guidance systems. Lest you fear an insect-drone infestation near your workplace or home, researchers are testing the technology in the safety of the lab–the dragonflies are not being released into the wild, according to Register.

How did the micro-drones come to be?

Researchers at Howard Hughes first genetically modified the dragonflies so that the insects’ neurons associated with its wings now respond to pulses of light. A micro-navigation system sends commands via pulses of light that travel through an optical nerve stimulator to guide the flight path and actions of the dragonfly.

Register says the technology is not ready to leave the lab, but the DragonflEye project is a “broad” technology platform with boundless potential commercial applications.

The applications range from search-and-rescue operations in dangerous buildings to environmental monitoring and large-scale crop pollination, says Register. (The technology, for instance, could be applied to bees to pollinate flowers, according to Draper.)

Other applications could include tracking small animals to help scientists better understand behavior in the wild, or equipping insects with environmental sensors to monitor the influence of climate change. Register says the data from these dragonfly missions could help guide policies to protect fragile ecosystems.

Draper is still looking for a partner to develop the commercial applications, says Register, but he says the platform could be the future of drone technology.

“DragonflEye is the perfect package–it’s a totally new kind of micro-aerial vehicle that’s smaller, lighter, and stealthier than anything else that’s manmade,” says Register.

Back in January, Jesse Wheeler, another biomedical engineer at Draper, said the DragonflEye project is not being funded by the military or government. Nor does anyone need to worry about dragonflies being “weaponized” or leading covert operations, he added.

“Make no mistake: We are not releasing dragonflies to do surveillance or reconnaissance missions,” said Wheeler.

https://player.vimeo.com/video/219709402

First Look: Behind-the-scenes with DragonflEye from Draper on Vimeo.

*** Editor’s Note: Will they will require some VERY SMALL, very light but ENERGY DENSE Power Sources?

Advanced (SWIR) Quantum Dots Offer Solution for Tagging and Imaging the Biological Processes in LIVE Animals


nanocrystalsFluorescent quantum dots are valuable tools used to tag and image biological processes in live animals. However, precise fluorescent imaging at the cellular and molecular levels has not been possible because of non-specific fluorescence and light scattering by surrounding tissues.

Now researchers have created short wave infrared (SWIR) quantum dots that resolve many of these problems. The system was used in live mice to image working organs, take metabolic measurements, and track microvascular blood flow in normal brain and brain tumors.

“Quantum dots are small (nanoscale) particles that can be engineered to emit light at different wavelengths,” explains Behrouz Shabestari, Ph.D., director of the Optical Imaging Program at NIH’s National Institute of Biomedical Imaging and Bioengineering, which co-funded the research. “When they are injected into a live animal, the emitted fluorescent light can be seen with special cameras. By engineering the dots to bind to specific tissues of interest, researchers can use them to study biological processes in real-time.” qdot_tech_note_graph
An international group of investigators led by Moungi G. Bawendi, Ph.D., the Lester Wolfe Professor in Chemistry at the Massachusetts Institute of Technology, collaborated to create what Bawendi calls the “next-generation,” of quantum dots.
Said Bawendi, “We took advantage of the special qualities of short wave infrared light, which is essentially the ability to give a clear bright signal emitted from the tissue of interest that is not blocked or scattered by the surrounding tissues. The system allows us to view biological processes in living, moving animals with great clarity and detail.”
The work is described in the April issue of the journal Nature Biomedical Engineering (“Next-generation in vivo optical imaging with short-wave infrared quantum dots”).
experimental set-up with composite SWIR quantum dots injected into the circulation and then imaged through a cranial window in the mouse brain
The top outlines the experimental set-up with composite SWIR quantum dots injected into the circulation and then imaged through a cranial window in the mouse brain. The bottom shows the resulting fluorescent image with healthy arteries in red, veins in blue, and the disorganized blood vessels of a brain tumor in green.

Engineering SWIR quantum dots to target tissues of interest

While the inner core of a SWIR quantum dot (SWIR-QDs) generates the unique fluorescent properties of short wave infrared light, the other critical component of the dot is the outer surface, which must be engineered to target a tissue of interest. The researchers call this “functionalization,” which means making them useful for studying specific tissues and biological processes. Bawendi and colleagues engineered three distinct types of SWIR quantum dots to demonstrate their use in studying different biological processes.
The first type of SWIR-QDs were engineered with phospholipid micelle surface coatings. Micelles are small particles that have a hydrophilic (water-loving) outer shell and a hydrophobic (water repelling) inner layer. The micelle-embedded SWIR-QDs dissolved and circulated through the bloodstream for an extended period, allowing the researchers to study heart and respiration rates in awake mice.
The advantage of these SWIR-QDs is the ability to image physiological processes that occur too rapidly to be detected by common imaging methods such as MRI or PET. This ability would allow unobtrusive monitoring of animals in their normal environment for changes in heartbeat and breathing rates during various exercise tests or in response to drug candidates for conditions such as cardiac arrhythmia.
The second type of SWIR-QDs created were embedded in chylomicrons. Chylomicrons are lipoprotein particles that consist of triglycerides, phospholipids, cholesterol, and proteins and are known to transport dietary lipids from the intestines to other locations.

These SWIR-QDs were used to study the movement and metabolism of lipids between brown adipose tissue, blood, and liver in real-time. The researchers explained that lipid-coated SWIR-QDs could be used to assess the immediate effects of medications designed to affect lipid metabolism—for example, to increase the liver’s uptake of lipids from the bloodstream of an individual with high cholesterol.

SWIR quantum dot imaging
a) Experimental set-up with lipid micelle SWIR quantum dots injected into the circulation and whole body scan with SWIR camera. b) Resulting fluorescent image shows the accumulation of the lipid micelle SWIR quantum dots in the liver (blue circle) and heart (red circle).
The third type of SWIR-QDs were composites, containing multiples QDs, and coated with PEG, which allows them to dissolve in blood. This third type was used to measure blood flow in the vasculature of the mouse brain by tracking individual SWIR-QD composite particles as they moved through the blood vessels. The researchers could view the dramatic differences between blood flow in healthy vasculature and in vessels at the margin of a brain tumor.
These SWIR-QDs would make it possible to measure blood flow in the brain before and after a stroke, and changes in response to experimental stroke medications.
“In addition to the ability to test much-needed new medications to treat stroke, the potential application to difficult-to-treat tumors is one that we are also very excited about,” said Bawendi. “We can potentially use SWIR-QDs to study how the blood flow pattern in a tumor changes over time. We could monitor disease progression or regression in response to drug treatment.

This opens a new way to assess experimental treatments for both stroke and brain cancer that have not been possible with other imaging methods.”

Source: National Institute of Biomedical Imaging and Bioengineering

Read more: Advanced quantum dots shed bright light on biological processes

Making Hydrogen Production Cheaper using New Ultra-Thin nano-material for splitting water


newultrathinThis is a water drop falling into water. Credit: Sarp Saydam/UNSW

UNSW Sydney chemists have invented a new, cheap catalyst for splitting water with an electrical current to efficiently produce clean hydrogen fuel.

The technology is based on the creation of ultrathin slices of porous metal-organic complex coated onto a foam electrode, which the researchers have unexpectedly shown is highly conductive of electricity and active for .

“Splitting water usually requires two different catalysts, but our catalyst can drive both of the reactions required to separate water into its two constituents, oxygen and hydrogen,” says study leader Associate Professor Chuan Zhao.

“Our fabrication method is simple and universal, so we can adapt it to produce ultrathin nanosheet arrays of a variety of these materials, called .

“Compared to other water-splitting electro-catalysts reported to date, our is also among the most efficient,” he says.

The UNSW research by Zhao, Dr Sheng Chen and Dr Jingjing Duan is published in the journal Nature Communications.

Hydrogen is a very good carrier for renewable energy because it is abundant, generates zero emissions, and is much easier to store than other energy sources, like solar or wind energy.

But the cost of producing it by using electricity to split water is high, because the most efficient catalysts developed so far are often made with precious metals, like platinum, ruthenium and iridium.

The catalysts developed at UNSW are made of abundant, non-precious metals like nickel, iron and copper. They belong to a family of versatile porous materials called , which have a wide variety of other potential applications.

Until now, metal-organic frameworks were considered poor conductors and not very useful for electrochemical reactions. Conventionally, they are made in the form of bulk powders, with their catalytic sites deeply embedded inside the pores of the material, where it is difficult for the water to reach.

By creating nanometre-thick arrays of metal-organic frameworks, Zhao’s team was able to expose the pores and increase the surface area for electrical contact with the .

“With nanoengineering, we made a unique metal-organic structure that solves the big problems of conductivity, and access to active sites,” says Zhao.

“It is ground-breaking. We were able to demonstrate that metal-organic frameworks can be highly conductive, challenging the common concept of these materials as inert electro-catalysts.”

Metal-organic frameworks have potential for a large range of applications, including fuel storage, drug delivery, and carbon capture. The UNSW team’s demonstration that they can also be highly conductive introduces a host of new applications for this class of material beyond electro-catalysis.

Explore further: Researchers report new, more efficient catalyst for water splitting

More information: Jingjing Duan et al, Ultrathin metal-organic framework array for efficient electrocatalytic water splitting, Nature Communications (2017). DOI: 10.1038/ncomms15341

 

 

New Novel Nanowires open up new Possibilities in Nano-Electronics (Molecular Electronics)


Nanowires id46974_1Schematic representation of the folding and anchoring processes needed to obtain π-folded molecular junctions from a representative member of the foldamer family studied in this work. (© Nature) (click on image to enlarge)
The current demand for small-sized electronic devices is calling for fresh approaches in their design.A group of researchers at the Basque Excellence Research Center into Polymers (POLYMAT), the University of the Basque Country (UPV/EHU), the University of Barcelona, the Institute of Bioengineering of Barcelona (IBEC), and the University of Aveiro, and led by Aurelio Mateo-Alonso, the Ikerbasque research professor at POLYMAT, have developed a new suite of molecular wires or nanowires that are opening up new horizons in molecular electronics.The research is being published today in the prestigious journal Nature Communications (“High conductance values in π-folded molecular junctions”).

The growing demand for increasingly smaller electronic devices is prompting the need to produce circuits whose components are also as small as possible, and this is calling for fresh approaches in their design.

Molecular electronics has sparked great interest because the manufacture of electronic circuits using molecules would entail a reduction in their size.
Nanowires are conducting wires on a molecular scale that carry the current inside these circuits. That is why the efficiency of these wires is crucially important.
In fact, one of the main novelties in this new suite of nanowires developed by the group led by Aurelio Mateo lies in their high efficiency, which constitutes a step forward in miniaturizing electronic circuits.
Source: University of the Basque Country

 

%d bloggers like this: