Articles from July 2015

Fuel Cell Electrodes 7 Times More Efficient

A new fabrication technique that produces platinum hollow nanocages with ultra-thin walls could dramatically reduce the amount of the costly metal needed to provide catalytic activity in such applications as fuel cells. The technique uses a solution-based method for producing atomic-scale layers of platinum to create hollow, porous structures that can generate catalytic activity both inside and outside the nanocages. The layers are grown on palladium nanocrystal templates, and then the palladium is etched away to leave behind nanocages approximately 20 nanometers in diameter, with between three and six atom-thin layers of platinum. Use of these nanocage structures in fuel cell electrodes could increase the utilization efficiency of the platinum by a factor of as much as seven, potentially changing the economic viability of the fuel cells.

A transmission electron microscope image shows a typical sample of platinum cubic nanocages

We can get the catalytic activity we need by using only a small fraction of the platinum that had been required before,” said Younan Xia, a professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University. Xia also holds joint faculty appointments in the School of Chemistry and Biochemistry and the School of Chemical and Biomolecular Engineering at Georgia Tech. “We have made hollow nanocages of platinum with walls as thin as a few atomic layers because we don’t want to waste any material in the bulk that does not contribute to the catalytic activity.
The research – which also involved researchers at the University of Wisconsin-Madison, Oak Ridge National Laboratory, Arizona State University and Xiamen University in China – was reported in the July 24 issue of the journal Science.


Water-Repellent Paint

Late night revellers and heavy drinkers may think nothing of relieving themselves in public. But now walls are fighting back against the disgusting habit. Walls in San Francisco have been coated with water-repellent paint so that desperate drinkers get a nasty surprise if they urinate on them.

nanotechnology for coatings

Nine walls around the Mission and Soma districts have been treated with hydrophobic Ultra-Ever Dry paint, so that if someone wees on them, their urine sprays back over their legs and shoes, hopefully deterring them from urinating in public again. The nanotechnology spray can be applied to almost any material. It turns into a super hydrophobic shield when applied, so that breeze blocks can be made non-porous, walls hydrophobic and gloves completely dry even when submerged in water, for example. When liquid is sprayed onto a surface treated with Ultra-Ever Dry, the droplets remain almost spherical, so they can bounce off a surface.


How To Make Solar Energy Conversion More Efficient

When it comes to installing solar cells, labor cost and the cost of the land to house them constitute the bulk of the expense.  The solar cells – made often of silicon or cadmium telluride – rarely cost more than 20 percent of the total costSolar energy could be made cheaper if less land had to be purchased to accommodate solar panels, best achieved if each solar cell could be coaxed to generate more power.

A huge gain in this direction has now been made by a team of chemists at the University of California, Riverside (UCR) that has found an ingenious way to make solar energy conversion more efficientThe researchers report in Nano Letters that by combining inorganic semiconductor nanocrystals with organic molecules, they have succeeded in “upconvertingphotons in the visible and near-infrared regions of the solar spectrum.


Solar-panels UCRChemists at the University of California, Riverside have found an ingenious way to make solar energy conversion more efficient

The infrared region of the solar spectrum passes right through the photovoltaic materials that make up today’s solar cells,” explained Christopher Bardeen, a professor of chemistry. The research was a collaborative effort between him and Ming Lee Tang, an assistant professor of chemistry. “This is energy lost, no matter how good your solar cell.  The hybrid material we have come up with first captures two infrared photons that would normally pass right through a solar cell without being converted to electricity, then adds their energies together to make one higher energy photon.  This upconverted photon is readily absorbed by photovoltaic cells, generating electricity from light that normally would be wasted.”


Ultrathin Electronics At Nano Scale

Semiconductors, metals and insulators must be integrated to make the transistors that are the electronic building blocks of your smartphone, computer and other microchip-enabled devices. Today’s transistors are miniscule—a mere 10 nanometers wide—and formed from three-dimensional (3D) crystals.

But a disruptive new technology looms that uses two-dimensional (2D) crystals, just 1 nanometer thick, to enable ultrathin electronics. Scientists worldwide are investigating 2D crystals made from common layered materials to constrain electron transport within just two dimensions. Researchers had previously found ways to lithographically pattern single layers of carbon atoms called graphene into ribbon-like “wires” complete with insulation provided by a similar layer of boron nitride. But until now they have lacked synthesis and processing methods to lithographically pattern junctions between two different semiconductors within a single nanometer-thick layer to form transistors, the building blocks of ultrathin electronic devices. Now for the first time, researchers at the Department of Energy’s Oak Ridge National Laboratory (ONRL) have combined a novel synthesis process with commercial electron-beam lithography techniques to produce arrays of semiconductor junctions in arbitrary patterns within a single, nanometer-thick semiconductor crystal.

scalable arrays of semiconductor junctions

We can literally make any kind of pattern that we want,” said Masoud Mahjouri-Samani, who co-led the study with David Geohegan. Geohegan, head of ORNL’s Nanomaterials Synthesis and Functional Assembly Group at the Center for Nanophase Materials Sciences, is the principal investigator of a Department of Energy basic science project focusing on the growth mechanisms and controlled synthesis of nanomaterials.
Millions of 2D building blocks with numerous patterns may be made concurrently, Mahjouri-Samani added. In the future, it might be possible to produce different patterns on the top and bottom of a sheet.


Solar Panels: Perovskites Better Than Silicon

In the solar power research community, a new class of materials called perovskites is causing quite a buzz, as scientists search for technology that has a better “energy payback time” than the silicon-based solar panels currently dominating the market. Now, a new study by scientists at Northwestern University and the U.S. Department of Energy’s Argonne National Laboratory reports that perovskite modules are better than any commercially available solar technology when products are compared on the basis of energy payback time.

Solar panels are an investment — not only in terms of money, but also energy. It takes energy to mine, process and purify raw materials, and then to manufacture and install the final product. Energy payback time considers the energy that went into creating the product and is a more comprehensive way to compare solar technology than conversion efficiency. The research team reports the energy payback time for solar panel technology made with perovskites could be as quick as two to three months, easily beating silicon-based panels, which typically need about two years to return the energy investment.

perovskite solar panel

People see 11 percent efficiency and assume it’s a better product than something that’s 9 percent efficient,” said Fengqi You, corresponding author on the study and assistant professor of chemical and biological engineering at Northwestern’s McCormick School of Engineering and Applied Science. “But that’s not necessarily true. One needs to take a broad perspective when evaluating solar technology.”

In what’s called a cradle-to-grave life cycle assessment, You and his colleagues traced a product from the mining of its raw materials until its retirement in a landfill. They determined the ecological impacts of making a solar panel and calculated how long it would take to recover the energy invested.

The findings have been published in the journal Energy & Environmental Science .


Smart Windows

Researchers in the Cockrell School of Engineering at the University of Texas at Austin are one step closer to delivering smart windows with a new level of energy efficiency, engineering materials that allow windows to reveal light without transferring heat and, conversely, to block light while allowing heat transmission, as described in two new research papers. By allowing indoor occupants to more precisely control the energy and sunlight passing through a window, the new materials could significantly reduce costs for heating and cooling buildings.

In 2013, chemical engineering professor Delia Milliron and her team became the first to develop dual-band electrochromic materials that blend two materials with distinct optical properties for selective control of visible and heat-producing near-infrared light (NIR). The team now has engineered two new advancements in electrochromic materials — a highly selective cool mode and a warm mode — not thought possible several years ago.

The cool mode material is a major step toward a commercialized product because it enables control of 90 percent of NIR and 80 percent of the visible light from the sun and takes only minutes to switch between modes. The previously reported material could require hours. To achieve this high performance, Milliron and a team, including Cockrell School postdoctoral researcher Jongwook Kim and collaborator Brett Helms of the Lawrence Berkeley National Lab, developed a new nanostructured architecture for electrochromic materials that allows for a cool mode to block near-infrared light while allowing the visible light to shine through. This could help reduce energy costs for cooling buildings and homes during the summer. The researchers reported the new architecture in Nano Letters.

smart windows

We believe our new architected nanocomposite could be seen as a model material, establishing the ideal design for a dual-band electrochromic material,” Milliron said. “This material could be ideal for application as a smart electrochromic window for buildings.”


Bionic Eye Against Loss Of Vision

Surgeons in Manchester have performed the first bionic eye implant in a patient with the most common cause of sight loss in the developed world. Ray Flynn, 80, has dry age-related macular degeneration which has led to the total loss of his central vision. He is using a retinal implant which converts video images from a miniature video camera worn on his glasses.

central vision loss

He can now make out the direction of white lines on a computer screen using the retinal implant. Mr Flynn said he was “delighted” with the implant and hoped in time it would improve his vision sufficiently to help him with day-to-day tasks like gardening and shopping.

CLICK to enjoy the video




The bionic eye implant receives its visual information from a miniature camera mounted on glasses worn by the patient. The images are converted into electrical pulses and transmitted wirelessly to an array of electrodes attached to the retina. The electrodes stimulate the remaining retina’s remaining cells which send the information to the brain.



Nanotechnology Prevents Acne

Researcher and dermatologist, Adam Friedman, M.D., and colleagues from the George Washington University Medical Center, find that the release of nitric oxide over time may be a new way to treat and prevent acne through nanotechnology. This research, published in the Journal of Investigative Dermatology, identified that the nanoparticles were effective at killing Proprionobacterium acnes, the gram positive bacteria associated with acne, and even more importantly, they inhibited the damaging inflammation that result in the large, painful lesions associated with inflammatory acne.

Acne nanoparticleOur understanding of acne has changed dramatically in the last 15-20 years,” said Friedman, associate professor of dermatology at the GW School of Medicine and Health Sciences and co-author of the study. “Inflammation is really the driving force behind all types of acne. In this paper, we provide an effective a way to kill the bacterium that serves as a stimulus for Acne without using an antibiotic, and demonstrate the means by which nitric oxide inhibits newly recognized pathways central to the formation of a pimple, present in the skin even before you can see the acne.”


How To Construct Innovative Nanoforms From DNA Origami

DNA, the molecular foundation of life, has new tricks up its sleeve. The four bases from which it is composed snap together like jigsaw pieces and can be artificially manipulated to construct endlessly varied forms in two and three dimensions. The technique, known as DNA origami, promises to bring futuristic microelectronics and biomedical innovations to market. Hao Yan, a researcher at Arizona State University’s Biodesign Institute (ASU), has worked for many years to refine the technique. His aim is to compose new sets of design rules, vastly expanding the range of nanoscale architectures generated by the method. In new research, a variety of innovative nanoforms are described, each displaying unprecedented design control. Yan directs the  Biodesign’s Center for Molecular Design and Biomimetics. In the current study, complex nano-forms displaying arbitrary wireframe architectures have been created, using a new set of design rules.


The images show the scaffold-folding paths for
A) star shape
B) 2-D Penrose tiling
C) 8-fold quasicrystalline 2-D pattern
D) waving grid.
E) circle array.
F) fishnet pattern
G) flower and bird design
The completed nanostructures are seen in the accompanying atomic force microscopy images.


Earlier design methods used strategies including parallel arrangement of DNA helices to approximate arbitrary shapes, but precise fine-tuning of DNA wireframe architectures that connect vertices in 3D space has required a new approach,” Yan says. Yan has long been fascinated with Nature’s seemingly boundless capacity for design innovation. The new study describes wireframe structures of high complexity and programmability, fabricated through the precise control of branching and curvature, using novel organizational principles for the designs. (Wireframes are skeletal three-dimensional models represented purely through lines and vertices.) The resulting nanoforms include symmetrical lattice arrays, quasicrystalline structures, curvilinear arrays, and a simple wire art sketch in the 100-nm scale, as well as 3D objects including a snub cube with 60 edges and 24 vertices and a reconfigurable Archimedean solid that can be controlled to make the unfolding and refolding transitions between 3D and 2D.

The research appears in the advanced online edition of the journal Nature Nanotechnology.


Solar Fuel Cell For Hydrogen Electric Car

Why not a solar cell that that produces fuel rather than electricity? Researchers at Eindhoven University of Technology (TU/e) (Netherlands) and FOM Foundation today present a very promising prototype of this in the journal Nature Communications. The material gallium phosphide enables their solar cell to produce the clean fuel hydrogen gas from liquid water. Processing the gallium phosphide in the form of very small nanowires is novel and helps to boost the yield by a factor of ten. And does so using ten thousand times less precious material.

hydrogen electric car
The electricity produced by a solar cell can be used to set off chemical reactions. If this generates a fuel, then one speaks of solar fuels – a hugely promising replacement for polluting fuels. One of the possibilities is to split liquid water using the electricity that is generated (electrolysis). Among oxygen, this produces hydrogen gas that can be used as a clean fuel in the chemical industry or combusted in fuel cells – in cars for example – to drive engines.

To connect an existing silicon solar cell to a battery that splits the water may well be an efficient solution now but it is a very expensive one. Many researchers are therefore targeting their search at a semiconductor material that is able to both convert sunlight into an electrical charge and split the water, all in one; a kind of ‘solar fuel cell’. Researchers at TU/e and FOM see their dream candidate in gallium phosphide (GaP), a compound of gallium and phosphide that also serves as the basis for specific colored leds.

has good electrical properties but the drawback that it cannot easily absorb light when it is a large flat surface as used in GaP solar cells. The researchers have overcome this problem by making a grid of very small GaP nanowires, measuring five hundred nanometers (a millionth of a millimeter) long and ninety nanometers thick. This immediately boosted the yield of hydrogen by a factor of ten to 2.9 percent. A record for GaP cells, even though this is still some way off the fifteen percent achieved by silicon cells coupled to a battery.

According to research leader and TU/e professor Erik Bakkers, it’s not simply about the yield – where there is still a lot of scope for improvement he points out: “For the nanowires we needed ten thousand less precious GaP material than in cells with a flat surface. That makes these kinds of cells potentially a great deal cheaper,” Bakkers says. “In addition, GaP is also able to extract oxygen from the water – so you then actually have a fuel cell in which you can temporarily store your solar energy. In short, for a solar fuels future we cannot ignore gallium phosphide any longer.”


How To Wireless Control Neurons

National Institutes of Health (NIH)-funded scientists developed an ultra-thin, minimally invasive device for controlling brain cells with drugs and light.

A study showed that scientists can wirelessly determine the path a mouse walks with a press of a button. Researchers at the Washington University School of Medicine, St. Louis, and University of Illinois, Urbana-Champaign, created a remote controlled, next-generation tissue implant that allows neuroscientists to inject drugs and shine lights on neurons deep inside the brains of mice. The revolutionary device is described online in the journal Cell. Its development was partially funded by the National Institutes of Health.

brain implantScientists used soft materials to create a brain implant a tenth the width of a human hair that can wirelessly control neurons with lights and drugs.
“It unplugs a world of possibilities for scientists to learn how brain circuits work in a more natural setting.” said Michael R. Bruchas, Ph.D., associate professor of anesthesiology and neurobiology at Washington University School of Medicine and a senior author of the study.

The Bruchas lab studies circuits that control a variety of disorders including stress, depression, addiction, and pain. Typically, scientists who study these circuits have to choose between injecting drugs through bulky metal tubes and delivering lights through fiber optic cables. Both options require surgery that can damage parts of the brain and introduce experimental conditions that hinder animals’ natural movements.

To address these issues, Jae-Woong Jeong, Ph.D., a bioengineer formerly at the University of Illinois at Urbana-Champaign, worked with Jordan G. McCall, Ph.D., a graduate student in the Bruchas lab, to construct a remote controlled, optofluidic implant. The device is made out of soft materials that are a tenth the diameter of a human hair and can simultaneously deliver drugs and lights.

“We used powerful nano-manufacturing strategies to fabricate an implant that lets us penetrate deep inside the brain with minimal damage,” said John A. Rogers, Ph.D., professor of materials science and engineering, University of Illinois at Urbana-Champaign and a senior author. “Ultra-miniaturized devices like this have tremendous potential for science and medicine.”


How To Fight Thrombotic Disease

Future Science Group (FSG) today announced the publication of a new article in Future Science OA, covering the use of nanocarriers and microbubbles in drug delivery for thrombotic disease.

Ischemic heart disease and stroke caused by thrombus formation are responsible for more than 17 million deaths per year worldwide. Molecules with thrombolytic capacities have been developed and some of them are in clinical practice. However, some patients treated with these molecules develop lethal intracranial hemorrhages. Furthermore, these molecules are rapidly degraded in the blood stream, and therefore large amounts of drugs are needed to be efficacious.

Research has focused on protecting thrombolytic molecules and enhancing their accumulation in clots. In this context, nanoparticles are interesting tools as the drugs can be loaded onto them and are thus protected from degradation in the body. Moreover, thrombus-targeting peptides have been used to concentrate the nanoparticles loaded with thrombolytic molecules into the thrombus.
nanoparticle against brain cancerWith millions of deaths per year resulting from thrombosis, it is important to improve drug delivery and the subsequent outcomes,” commented Francesca Lake, Managing Editor. “This review provides an excellent overview of where we stand thus far with utilizing nanoscale technology to solve this issue.”