You might not have heard of them, but these new materials will change the world


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** Contributed by Tim Harper: Entrepreneurial Technology Company Director and Consultant

New materials can change the world. There is a reason we talk about the Bronze Age and the Iron Age. Concrete, stainless steel, and silicon made the modern era possible. Now a new class of materials, each consisting of a single layer of atoms, are emerging, with far-reaching potential. Known as two-dimensional materials, this class has grown within the past few years to include lattice-like layers of carbon (graphene), boron (borophene) and hexagonal boron nitride (aka white graphene), germanium (germanene), silicon (silicene), phosphorous (phosphorene) and tin (stanene). More 2-D materials have been shown theoretically possible but not yet synthesized, such asgraphyne from carbon. Each has exciting properties, and the various 2-D substances can be combined like Lego bricks to build still more new materials.

This revolution in monolayers started in 2004 when two scientists famously created 2-D graphene using Scotch tape—probably the first time that Nobel-prize-winning science has been done using a tool found in kindergarten classrooms. Graphene is stronger than steel, harder than diamond, lighter than almost anything, transparent, flexible, and an ultrafast electrical conductor. It is also impervious to most substances except water vapor, which flows freely through its molecular mesh.

What Is Graphene

 

 

Initially more costly than gold, graphene has tumbled in price thanks to improved production technologies. Hexagonal boron nitride is now also commercially available and set to follow a similar trajectory. Graphene has become cheap enough to incorporate it in water filters, which could make desalination and waste-water treatment far more affordable. As the cost continues to fall, graphene could be added to road paving mixtures or concrete to clean up urban air—on top of its other strengths, the stuff absorbs carbon monoxide and nitrogen oxides from the atmosphere.

 

Other 2-D materials will probably follow the trajectory that graphene has, simultaneously finding use in high-volume applications as the cost falls, and in high-value products like electronics as technologists work out ways to exploit their unique properties. Graphene, for example, has been used to make flexible sensors that can been sewn into garments — or now actually 3-D printed directly into fabrics using new additive manufacturing techniques. When added to polymers, graphene can yield stronger yet lighter airplane wings and bicycle tires.

 

Hexagonal boron nitride has been combined with graphene and boron nitride to improve lithium-ion batteries and supercapacitors. By packing more energy into smaller volumes, the materials can reduce charging times, extend battery life, and lower weight and waste for everything from smart phones to electric vehicles.

Whenever new materials enter the environment, toxicity is always a concern. It’s smart to be cautious and to keep an eye out for problems. Ten years of research into the toxicology of graphene has, so far, yielded nothing that raises any concerns over its effects on health or the environment. But studies continue.

The invention of 2-D materials has created a new box of powerful tools for technologists. Scientists and engineers are excitedly mixing and matching these ultrathin compounds — each with unique optical, mechanical and electrical properties — to produce tailored materials optimized for a wide range of functions. Steel and silicon, the foundations of 20th-century industrialization, look clumsy and crude by comparison.

 

This is part of a series on the top 10 emerging technologies of 2016, developed in collaboration with Scientific American.

Read Genesis Nanotech Online: Latest “Nano-News” and Updates: The “Power of the ‘Nano-Gene Chip’


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Nano Power Chip NW U 062316 id43777Northwestern University: The Power of the “Gene Chip” Coming to Nanotechnology: Ability to Rapidly Test Millions/ Billions of Nanoparticles at ONE Time

 

Nano Theranostics 062316 118301_webNanotheranostics – The power of nanomedicine

 

 

 

QD Solar untitledToronto’s QD (Quantum Dot) Solar Sole Canadian among five winners of solar technology challenge

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Northwestern University: The Power of the “Gene Chip” Coming to Nanotechnology: Ability to Rapidly Test Millions/ Billions of Nanoparticles at ONE Time


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A combinatorial library of polyelemental nanoparticles was developed using Dip-Pen Nanolithography. This novel nanoparticle library opens up a new field of nanocombinatorics for rapid screening of nanomaterials for a multitude of properties. (Image: Peng-Cheng Chen/James Hedrick)

The discovery power of the “gene chip” is coming to nanotechnology. A Northwestern University research team is developing a tool to rapidly test millions and perhaps even billions or more different nanoparticles at one time to zero in on the best particle for a specific use.

When materials are miniaturized, their properties — optical, structural, electrical, mechanical and chemical — change, offering new possibilities. But determining what nanoparticle size and composition are best for a given application, such as catalysts, biodiagnostic labels, pharmaceuticals and electronic devices, is a daunting task.
“As scientists, we’ve only just begun to investigate what materials can be made on the nanoscale,” said Northwestern’s Chad A. Mirkin, a world leader in nanotechnology research and its application, who led the study. “Screening a million potentially useful nanoparticles, for example, could take several lifetimes. Once optimized, our tool will enable researchers to pick the winner much faster than conventional methods. We have the ultimate discovery tool.”
Using a Northwestern technique that deposits materials on a surface, Mirkin and his team figured out how to make combinatorial libraries of nanoparticles in a very controlled way. (A combinatorial library is a collection of systematically varied structures encoded at specific sites on a surface.) Their study will be published June 24 by the journal Science.
Nano Power Chip NW U 062316 id43777The nanoparticle libraries are much like a gene chip, Mirkin says, where thousands of different spots of DNA are used to identify the presence of a disease or toxin. Thousands of reactions can be done simultaneously, providing results in just a few hours.

 

Similarly, Mirkin and his team’s libraries will enable scientists to rapidly make and screen millions to billions of nanoparticles of different compositions and sizes for desirable physical and chemical properties.

“The ability to make libraries of nanoparticles will open a new field of nanocombinatorics, where size — on a scale that matters — and composition become tunable parameters,” Mirkin said. “This is a powerful approach to discovery science.”
Mirkin is the George B. Rathmann Professor of Chemistry in the Weinberg College of Arts and Sciences and founding director of Northwestern’s International Institute for Nanotechnology.
“I liken our combinatorial nanopatterning approach to providing a broad palette of bold colors to an artist who previously had been working with a handful of dull and pale black, white and grey pastels,” said co-author Vinayak P. Dravid, the Abraham Harris Professor of Materials Science and Engineering in the McCormick School of Engineering.
Using five metallic elements — gold, silver, cobalt, copper and nickel — Mirkin and his team developed an array of unique structures by varying every elemental combination. In previous work, the researchers had shown that particle diameter also can be varied deliberately on the 1- to 100-nanometer length scale.
Some of the compositions can be found in nature, but more than half of them have never existed before on Earth. And when pictured using high-powered imaging techniques, the nanoparticles appear like an array of colorful Easter eggs, each compositional element contributing to the palette.
To build the combinatorial libraries, Mirkin and his team used Dip-Pen Nanolithography, a technique developed at Northwestern in 1999, to deposit onto a surface individual polymer “dots,” each loaded with different metal salts of interest. The researchers then heated the polymer dots, reducing the salts to metal atoms and forming a single nanoparticle. The size of the polymer dot can be varied to change the size of the final nanoparticle.
This control of both size and composition of nanoparticles is very important, Mirkin stressed. Having demonstrated control, the researchers used the tool to systematically generate a library of 31 nanostructures using the five different metals.
To help analyze the complex elemental compositions and size/shape of the nanoparticles down to the sub-nanometer scale, the team turned to Dravid, Mirkin’s longtime friend and collaborator. Dravid, founding director of Northwestern’s NUANCE Center, contributed his expertise and the advanced electron microscopes of NUANCE to spatially map the compositional trajectories of the combinatorial nanoparticles.
Now, scientists can begin to study these nanoparticles as well as build other useful combinatorial libraries consisting of billions of structures that subtly differ in size and composition. These structures may become the next materials that power fuel cells, efficiently harvest solar energy and convert it into useful fuels, and catalyze reactions that take low-value feedstocks from the petroleum industry and turn them into high-value products useful in the chemical and pharmaceutical industries.
Source: Northwestern University

 

Nanotheranostics – The power of nanomedicine


Nano Theranostics 062316 118301_web

 

The future of medicine is now dawning upon us.

Nanomedicines demonstrate the capability to enhance drug properties by offering protection from degradation, enabling controlled release and biodistribution and increasing bioavailability. In fact, the term “nanotheranostics” has been proposed to describe a new class of nanomedicines which integrates the simultaneous detection and treatment of a disease. Many creative approaches have been proposed to co-deliver imaging and therapeutic agents too.

World Scientific’s latest book “Nanotheranostics for Personalized Medicine” provides principles of imaging techniques and concrete examples of advances and challenges in the development of nanotheranostics for personalized medicine.

The chapters discuss combining imaging and drug delivery for the treatment of severe diseases, how non-ionizing nanomedicine can be used as contrast agents to increase sensitivity for medical imaging, and how the practical clinical utility is advanced in personalized medicine along with the capabilities and lessons learned for pharmacology and pharmaceutics.

Readers of the book can also expect to read about the application of nanotheranostics in cardiovascular diseases and gene therapy. In addition, there will be a chapter on Plasmonic Nanoparticles-Coated Microbubbles for Theranostic Applications.

Edited by Simona Mura (University Paris Sud XI, France), Patrick Couvreur (University Paris Sud XI, France), Nanotheranostics for Personalized Medicine is on sale in major bookstores, including Amazon, and retails for US$154/ £111.

Previously from Our Blog Also Read …

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How Nanotechnology is Poised to Change Medicine Forever

*** Re-Posted from “Big Think” Science fiction movies such as Ant-Man and Fantastic Voyage excite us about the possibility of shrinking ourselves down to the subatomic level. In the Disney version of The Sword in the Stone, Merlin defeats the sorceress Madam Mim in a shape shifting battle by turning into a microbe which makes […] Click the Link above to Read the Full Article …

Why India Needs Nanotechnology Regulation Before it is Too Late


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“For us (India) to fully harness the advances made in nanotechnology and consolidate our leadership in the field, we must work towards building a regulatory framework encompassing public safety.” – Prateek Sibal

India ranks third in the number of research publications in nanotechnology, only after China and the US. This significant share in global nanotech research is a result of sharp focus by the Department of Science and Technology (DST) to research in the field in the country. The unprecedented funding of Rs 1,000 crore for the Nano Mission was clearly dictated by the fact that India had missed the bus on the micro-electronic revolution of the 1970s and its attendant economic benefits that countries like China, Taiwan and South Korea continue to enjoy to this day.

At the same time, the success of the Nano Mission is not limited to research but also involves training the required human resource for further advancement in the field. An ASSOCHAM and TechSci Research study reported in 2014: “From 2015 onwards, global nanotechnology industry would require about two million professionals and India is expected to contribute about 25% professionals in the coming years.”

A missing element in India’s march towards becoming a nanotechnology powerhouse is the lack of focus on risk analysis and regulation. A survey of Indian practitioners working in the area of nano-science and nanotechnology research showed that 95% of the practitioners recognised ethical issues in nanotech research. Some of these concerns relate to the possibly adverse effects of nanotechnology on the environment and humans, their use as undetectable weapon in warfare, and the incorporation of nano-devices as performance enhancers in human beings.

One reason for lack of debate around ethical, and public-health and -safety, concerns around new technologies could be the exalted status that science and its practitioners enjoy in the country. A very successful space program and a largely indigenous nuclear program has ensured that policymakers spend much of their time feting achievements of Indian science than discussing the risks associated with new technologies or improving regulation.

It is not surprising then that products like silver-nano washing machines or insecticides with nanoparticles continue to be sold in the Indian market without any analysis of the risk associated with their use. This – despite the fact that the government itself has acknowledged that nanoparticles of sizes comparable to that of human cells can be deposited in lungs and “may cause damage by acting directly at the site of deposition by translocating to other organs or by being absorbed through the blood.”

A study by the Massachusetts Institute of Technology, Boston, on the toxicity of nano-materials found that carbon nanoparticles inhaled by rats “reached the olfactory bulb and also the cerebrum and cerebellum, suggesting that translocation to the brain occurred through the nasal mucosa along the olfactory nerve to the brain.” This ability to translocate opens up questions about the effect different types of nanoparticles could have on human health.

Many commonly used products have nanoparticles; for instance, titanium dioxide nanoparticles are widely used in sunscreens and cosmetics as sun-protection. In the US, the National Institute of Occupational Safety and Health has issued safe occupational exposure limit of 0.1 mg/m3 for nanoscale titanium dioxide. This was after reports of incidences of lung cancer in rats at doses of 10 mg/m3 and above surfaced. There is also a concern that nano-scale titanium dioxide particles have higher photo-reactivity than coarser particles, and may generate free radicals that can damage cells.

The challenge that remains in front of policymakers is that of regulating a field where vast areas of knowledge are still being investigated and are unknown. In this situation, over-regulation may end up stifling further development while under-regulation could expose the public to adverse health effects. Further, India’s lack of investment in risk studies only sustains the lull in the policy establishment when it comes to nanotech regulations.

The Energy and Resources Institute has extensively studied regulatory challenges posed by nanotechnology and advocates that an “incremental approach holds out some promise and offers a reconciliation between the two schools- one advocating no regulation at present given the uncertainty and the other propounding a stand-alone regulation for nanotechnology.”

Kesineni Srinivas, the Member of Parliament from Vijayawada, has taken cognisance of the need for incremental regulation in nanotechnology from the view point of public health and safety. (Disclosure: The author worked with the Vijayawada MP on drafting the legislation on nanotechnology regulation, introduced in the winter session of Parliament, 2015.)

In December 2015, Srinivas introduced the Insecticides (Amendment) Bill in the Lok Sabha to grant only a provisional registration to insecticides containing nanoparticles with a condition that “it shall be mandatory for the manufacturer or importer to report any adverse impact of the insecticide on humans and environment in a manner specified by the Registration Committee.” This is an improvement over the earlier process of granting permanent registration to insecticides. However, the fate of the bill remains uncertain as only 14 private member bills have been passed in Parliament since the first Lok Sabha in 1952.

More recently, the DST released the ‘Guidelines and best practices for safe handling of nano-materials in research laboratories and industries’. The guidelines which are precautionary in nature lay out methods for safe handling and disposal of nanoparticles by researchers and the industry. Though much delayed, it is a welcome step towards safer nanotechnology research in India.

For us to fully harness the advances made in nanotechnology and consolidate our leadership in the field, we must work towards building a regulatory framework encompassing public safety. Without such a provision, any mishap or catastrophe precipitated by the use of nanotechnology could leave a great opportunity out of our reach.

Prateek Sibal will be joining Sciences Po (the Paris Institute of Political Sciences), Paris, as a Charpak Scholar in 2016.

Perovskite phosphor boosts visible light communication: Flashy nanocrystals help LEDs send data in the blink of an eye


Flashy NP Perovskite 1466097172999A green-emitting perovskite nanocrystal phosphor mixed with a red-emitting nitride phosphor looks yellow under ambient light (left). When excited by blue laser light, the phosphor combination produces white light (right).
Credit: Osman Bakr

 

Light-emitting diodes (LEDs) are increasingly used to illuminate homes and offices; soon, the same lights could also transmit data to your computer or smartphone in photon pulses so fast the eye can’t see them. But this form of visible light communication faces two key challenges: The light must flicker fast enough to carry sizeable amounts of data; and at the same time it should provide the warm, balanced color tones needed for pleasant ambient lighting.

 

Nanocrystals of cesium lead bromide (CsPbBr3) could help to solve both problems, according to a team led by Boon S. Ooi and Osman M. Bakr at King Abdullah University of Science & Technology (KAUST). They have found that LEDs coated with the material can reach high data transmission rates of 2 gigabits per second, comparable to the fastest Wi-Fi, while producing a quality of light that matches commercial white-light LEDs (ACS Photonics 2016, DOI: 10.1021/acsphotonics.6b00187).

 

Visible light communication, sometimes called Li-Fi, is already finding real-world applications. Last year, for example, Dutch company Phillips installed a smart LED system in a French supermarket that uses Li-Fi to transmit discount offers to shoppers’ cellphones, based on their location in the store. If data rates could be increased significantly, Li-Fi might add much-needed capacity to congested Wi-Fi networks that rely on radio waves.

 

And since the smart LEDs are doing double duty, by providing both lighting and communication, they offer an economical solution, says Bakr. Ooi adds that these systems do not even need a direct line of sight between LED and computer: “As long as your device can see light, you can detect a signal,” he says.

 

White-light LEDs typically contain a blue LED coated with phosphors that turn some of the light into green and red. But most phosphors take too long to recover between excitation and emission, pulsing no more than a few million times per second. Last year, other researchers showed that polymer semiconductors could reach more than 200 MHz (ACS Photonics2015, DOI: 10.1021/ph500451y).

 

The KAUST team instead turned to CsPbBr3, part of a family of materials known as perovskites that have become the darling of the photovoltaic research community. Perovskite solar cells have seen remarkable efficiency gains over the past seven years, and the materials are cheap and relatively easy to prepare in solution.

 

The team created nanocrystals of the perovskite, roughly 8 nm across, and found that their green emission faded in just seven nanoseconds. This allowed them to pulse reliably at almost 500 MHz, setting what the researchers believe is a new record for LED phosphors. “It is an extremely impressive and important achievement,” says Ted Sargent of the University of Toronto, who works on optoelectronic materials and has collaborated with the KAUST group in the past.

 

The rapid response is partly due to the size of the crystals, Bakr explains. When blue light excites an electron in the material, it forms an electron-hole pair called an exciton. The confines of the tiny crystal change the exciton’s energy levels, making the electron more likely to recombine with its hole and emit a photon.

 

When the researchers teamed the perovskite phosphor with a commercial red-emitting phosphor and a blue gallium nitride LED, the device produced a warm white light with a color rendering index of 89, as good as white LEDs already on the market (natural sunlight itself is rated at 100). “This quality makes this material ideal for low-power indoor illumination,” Sargent says.

 

Jakoah Brgoch of the University of Houston, who develops novel phosphors for LED lighting, says that it is relatively easy to fine-tune the chemistry of perovskites by substituting different halides or metal ions. “That means there’s a lot of potential to improve these properties,” he says.

Chemical & Engineering News ISSN 0009-2347 Copyright © 2016 American Chemical Society

Toronto’s QD (Quantum Dot) Solar sole Canadian among five winners of solar technology challenge


QD Solar untitledFive North American solar start-up companies have been selected to receive further support in developing their technology and moving them closer to market under the SunRISE TechBridge Challenge, which had 56 team entries.

Of the five winners, one is Canadian colloidal quantum dot cell developerQD Solar, which will gain support from Greentown Launch acceleration and DSM Partnership/Investment, as well as desk and lab space at Greentown Labs in Somerville, MA, and networking and coaching to accelerate their business and networking in the cleantech community in the Greater Boston area.

QD Solar uses low-cost, nano-engineered particles to produce solar cells that can capture wasted infrared light, resulting in a 20% increase in efficiency over conventional solar panels, based on research conducted at the Nanomaterials for Energy Laboratory in the University of Toronto’s Department of Electrical and Computer Engineering.

The SunRISE TechBridge Challenge challenged companies to present innovative solutions and new materials that will lower the levelized cost of energy (LCOE) for photovoltaic (PV) systems, including novel materials for existing and emerging high performance PV modules, technologies enabling non-traditional solar deployment, and business models that integrate solar PV with energy storage.

QD Solar started life at the University of Toronto and MaRS Innovation, and in March received $2.55 million from Sustainable Development Technology Canada (SDTC).

QDSolar

Conventional solar panels waste a large portion of available sun energy because their silicon solar cells can’t capture infrared light energy, a problem that QD Solar set out to solve with their proprietary quantum dot-based solar cells using nano-engineered, low-cost materials that can absorb infrared light.

QD Solar CEO Dan Shea is a former executive with Celestica and Blackberry.

In 2009, co-founder Edward Sargent and his team at the University of Toronto received a grant from King Abdullah University of Science and Technology (KAUST) in Saudi Arabia to advance their research into colloidal quantum dots for solar power applications.

The SunRISE TechBridge Challenge was organized by Fraunhofer TechBridge and the SunRISE Partners, which include Royal DSM and Greentown Labs.

The Fraunhofer TechBridge Challenge is an offering of the Fraunhofer Center for Sustainable Energy Systems (CSE), which organizes several industry-sponsored annual challenges to accelerate promising technologies through targeted industry-driven validation projects, including the SunRISE Challenge, Advanced Industrial Surfaces, the Microgrid Challenge, and the Innovation Ecosystem Program.

Fraunhofer Gesellschaft is a German applied R&D organization which has 66 institutes and independent research units throughout Germany and 80 institutes and centers around the world.

Nicola Bettio, a member of QD Solar’s Board of Directors, manages the KAUST Innovation Fund and anticipates the establishment of the company’s presence in a significant development facility in KAUST’s Research & Technology Park in the near future.

KAUST University: Partnering for sustainable fresh water production: Video


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Published online Jun 7, 2016

Combining methods for water desalination results in low-cost, highly efficient water production.

Innovative solutions to improve the efficiency of water desalination are a major focus in countries such as Saudi Arabia, where fresh water for industrial, agricultural and human use is scarce. A research partnership between KAUST and the National University of Singapore has won global acclaim for its unique and efficient yet low-cost method of conducting desalination called hybrid multi-effect adsorption desalination.

In a world of dwindling freshwater supply, how can we meet the demands of a growing population? This video explains a new hybrid process which can double the freshwater output of traditional thermally-driven desalination without requiring additional energy. Developed by the King Abdullah University of Science and Technology (KAUST) and the National University of Singapore (NUS), this desalination method is now being piloted for wider implementation by MEDAD, a KAUST-supported startup company. For more information on the new hybrid technology.

Video explains the hybrid process of adsorption desalination using animations.

© 2016 KAUST

The collaboration has resulted in two desalination pilot schemes—one at KAUST itself and the other at a second location also in Saudi Arabia—as well as a spin-off company called MEDAD that will help to commercialize the hybrid desalination technology. The project is led by Kim Choon Ng from the University’s Water Desalination and Reuse Center. Ng has devoted his career to finding ways of reducing the cost of desalination through novel technologies.

Traditional desalination techniques use membranes and pressure to separate salt and other minerals from seawater, but these techniques are expensive, energy intensive and inefficient.

“Desalination is particularly complicated in the challenging environment of the Gulf, where high salinity, silt levels and increased water temperatures make working with the seawater quite difficult,” Ng said. “The frequent occurrence of hazardous algal blooms has also contributed to high pre-treatment costs and severe fouling of membranes. These elements combine to considerably increase the overall unit cost of producing desalinated water.”

Ng and his team recognized that the only viable option to overcome these challenges was to base their system on thermal desalination rather than membrane-based techniques.

They investigated a combined technique and utilized an existing industrially-proven method called multi-effect distillation (MED). This involves spraying saline water over the outer surfaces of a series of tubes (or stages) arranged in a tower. At the top of the tower, saline water is fed in and heated by a steam-driven compressor. The resulting water vapor is collected while the salt is left behind. This process is repeated over subsequent stages, and the vapor from each stage is channeled through the tubes to the bottom of the tower, where it condenses to generate fresh water as it cools.

Ng’s team combined MED with a thermally-driven process called adsorption desalination (AD), which uses low-cost silica gel adsorbents with a very high affinity for water vapor. The researchers adapted the last stage of MED so that the vapor uptake is carried out by AD.

The water vapor is attracted to designated adsorption gel beds while the remaining gel beds undergo desorption, removing the water and preparing the silica gel for the next round. Crucially, there are no major moving parts in the AD cycle, meaning it uses far less energy than some other techniques, and it can run on waste heat from other industrial processes.

“The best part about AD is that it can be run at low temperatures and low pressures,” explained Ng. “In fact, we can run cycles at only 7°C and at a pressure of 2 kPa. This presents a unique opportunity to exploit the renewable energy resources that the Kingdom has—namely solar and geothermal energy—to run the system. Also, because we are producing cooling as part of the process, we can link into air-conditioning systems.”

Simulations on the hybrid MEDAD system indicate that it could double or even triple desalinated water production. Experiments conducted at the pilot plant at KAUST have already increased fresh water production by more than 50 percent. This represents the highest water production ever reported for a desalination technique and earned the team a GE-Aramco “Global Innovation Challenge” award in January 2015. The breakthrough also helps extend the lower end of the temperature range at which the system can operate, which has been a major limitation with MED in the past.

“This represents a major leap forward in water production using thermally-driven cycles, and it is attributed to the excellent thermodynamic synergy between MED and AD cycles,” noted Ng. “We believe it can be developed fully to an extent where the energy efficiency of desalination can meet the target needed for sustainability.”

————–

The technology has been licensed by the NUS Industry Liasion Office, part of the NUS Enterprise, and the University’s Innovation and Economic Development Office, to MEDAD.

 

Kim Choon Ng and Muhammad Wakil inspect the MEDAD hybrid desalination pilot at KAUST.

Kim Choon Ng and Muhammad Wakil inspect the MEDAD hybrid desalination pilot at KAUST.

© 2015 KAUST

Kim Choon Ng (left) explains the hybrid cycle to visitors at KAUST, including Ahmad Khowaiter from Saudi Aramco (center), Dr. Abdulrahman from the Saline Water Conversion Commission (SWCC) (right) and Dr. Ahmed Al Arifi from SWCC (far right).

Kim Choon Ng (left) explains the hybrid cycle to visitors at KAUST, including Ahmad Khowaiter from Saudi Aramco (center), Dr. Abdulrahman from the Saline Water Conversion Commission (SWCC) (right) and Dr. Ahmed Al Arifi from SWCC (far right).

© 2015 KAUST

 

Development of safe and durable high-temperature lithium-sulfur batteries: U of Western Ontario, Canada



Scheme of MLD alucone coated C-S electrode and cycle performance of stabilized high temperature Li-S batteries. (click on image to enlarge)

Posted: Jun 22, 2016

Safety has always been a major concern for electric vehicles, especially preventing fire and explosion incidents with the best possible battery technologies.

Lithium-sulfur batteries are considered as the most promising candidate for EVs due to their ultra-high energy density, which is over 5 times the capacity of standard commercial Li-ion batteries. This high density makes it possible for electric vehicles to travel longer distances without stopping for a charge.

However, batteries operating at the high temperatures necessary in electric vehicles presents a safety challenge, as fire and other incidents become more likely.

Prof. Andy Xueliang Sun and his University of Western Ontario research team, in collaboration with Dr. Yongfeng Hu and Dr. Qunfeng Xiao from the Canadian Light Source, have developed safe and durable high-temperature Li-S batteries using by a new coating technique called molecular layer deposition (MLD) technology for the first time. This research has been published in Nano Letters (“Safe and Durable High-Temperature Lithium–Sulfur Batteries via Molecular Layer Deposited Coating”).

TOC EV Battery diagram

Scheme of MLD alucone coated C-S electrode and cycle performance of stabilized high temperature Li-S batteries. (click on image to enlarge)

“Close collaboration with CLS to obtain such detailed information is very important to our understanding,” said Dr. Sun. “We need not only to design novel materials for energy storage, but also deep understanding on the science behind materials.”

“We demonstrated that MLD alucone coating offers a safe and versatile approach toward lithium-sulfer batteries at elevated temperature,” said Dr. Sun.

MLD is an ultrathin-film technique with applications in energy storage systems, providing precise and flexible control over film thickness and chemical composition of the target material at a molecular scale.

The MLD alucone coated carbon-sulfur electrodes demonstrated very stable and improved performance at temperatures as high as 55oC, which will significantly prolong battery life for high-temperature Li-S batteries.

X-ray studies at the CLS revealed the specific mechanism and interaction between sulfur and alucone MLD coating.

“By using synchrotron-based high energy X-ray photoelectron spectroscopy (HEXPS), it demonstrated the coating ends up hindering unwanted side reactions,” said Dr. Hu. This is achieved as the coating passivating the surface of the electrode.

Next up, the team will focus on the safe lithium sulfur batteries with synchrotron X-ray in-situ battery study in future.

Source: Canadian Light Source

Ultra-thin solar cells can easily bend around a pencil


Scientists in South Korea have made ultra-thin photovoltaics flexible enough to wrap around the average pencil. The bendy solar cells could power wearable electronics like fitness trackers and smart glasses. The researchers report the results in the journal Applied Physics Letters (“Ultra-thin Flexible GaAs Photovoltaics in Vertical Forms Printed on Metal Surfaces without Interlayer Adhesives”).

 

Bend solar Cells id43736Ultra-thin solar cells are flexible enough to bend around small objects, such as the 1mm-thick edge of a glass slide, as shown here. (Image: Juho Kim, et al/ APL)

 

Thin materials flex more easily than thick ones – think a piece of paper versus a cardboard shipping box. The reason for the difference: The stress in a material while it’s being bent increases farther out from the central plane. Because thick sheets have more material farther out they are harder to bend.

“Our photovoltaic is about 1 micrometer thick,” said Jongho Lee, an engineer at the Gwangju Institute of Science and Technology in South Korea. One micrometer is much thinner than an average human hair. Standard photovoltaics are usually hundreds of times thicker, and even most other thin photovoltaics are 2 to 4 times thicker.
The researchers made the ultra-thin solar cells from the semiconductor gallium arsenide. They stamped the cells directly onto a flexible substrate without using an adhesive that would add to the material’s thickness. The cells were then “cold welded” to the electrode on the substrate by applying pressure at 170 degrees Celcius and melting a top layer of material called photoresist that acted as a temporary adhesive. The photoresist was later peeled away, leaving the direct metal to metal bond.
The metal bottom layer also served as a reflector to direct stray photons back to the solar cells. The researchers tested the efficiency of the device at converting sunlight to electricity and found that it was comparable to similar thicker photovoltaics. They performed bending tests and found the cells could wrap around a radius as small as 1.4 millimeters.
The team also performed numerical analysis of the cells, finding that they experience one-fourth the amount of strain of similar cells that are 3.5 micrometers thick.
“The thinner cells are less fragile under bending, but perform similarly or even slightly better,” Lee said.
A few other groups have reported solar cells with thicknesses of around 1 micrometer, but have produced the cells in different ways, for example by removing the whole substract by etching.
By transfer printing instead of etching, the new method developed by Lee and his colleagues may be used to make very flexible photovoltaics with a smaller amount of materials.
The thin cells can be integrated onto glasses frames or fabric and might power the next wave of wearable electronics, Lee said.
Source: American Institute of Physics