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A new company Tenka Energy, LLC ™ has been formed to exploit and commercialize the Next Generation Super-Capacitors and Batteries. The opportunity is based on Nanoporous-Nickel Flexible Thin-Form, Scalable Super Capacitors and Si-Nanowire Battery Technologies with Exclusive IP Licensing Rights from Rice University.

… Problem 1: Current capacitors and batteries being supplied to the relevant markets lack the sustainable power density, discharge and recharge cycle and warranty life. Combined with a weight/ size challenge and the lack of a ‘flexible form factor’, existing solutions lack the ability to scale and manufacture at Low Cost, to satisfy the identified industries’ need for solutions that provide commercial viability & performance.

Solution: For Marine & Drone Batteries – Medical Devices

  • High Energy Density = 2X More Time on the Water; 2X Flight Time for Drones
  • Simplified Manufacturing = Lower Costs
  • Simple Electrode Architecture = Flex Form Factor (10X Energy Density Factor)
  • Flexible Form = Dramatically Less Weight and Better Weight Distribution
  • Easy to Scale Technology

To Read the Full Article Click on the Link Below:

  

 

Energy Storage: New Si-Nanowire Battery for Applications in Marine and Drone Battery Markets: w/Video

            

 

Image: UCF

Technology I: University of Central Florida

Leaving your phone plugged in for hours could become a thing of the past, thanks to a new type of battery technology that charges in seconds and lasts for over a week.

Watch the Video

While it probably won’t be commercially available for a years, the researchers said it has the potential to be used in phones, wearables and electric vehicles.

“If they were to replace the batteries with these supercapacitors, you could charge your mobile phone in a few seconds and you wouldn’t need to charge it again for over a week,” said Nitin Choudhary, a UCF postdoctoral associate, who conducted much of the research, published in the academic journal ACS Nano.

How does it work?

Unlike conventional batteries, supercapacitors store electricity statically on their surface which means they can charge and deliver energy rapidly. But supercapacitors have a major shortcoming: they need large surface areas in order to hold lots of energy.

To overcome the problem, the researchers developed supercapacitors built with millions of nano-wires and shells made from two-dimensional materials only a few atoms thick, which allows for super-fast charging. Their prototype is only about the size of a fingernail.

“For small electronic devices, our materials are surpassing the conventional ones worldwide in terms of energy density, power density and cyclic stability,” Choudhary said.

Cyclic stability refers to how many times a battery can be charged, drained and recharged before it starts to degrade. For lithium-ion batteries, this is typically fewer than 1,500 times.

Supercapacitors with two-dimensional materials can be recharged a few thousand times. But the researchers say their prototype still works like new even after being recharged 30,000 times.

 

wearable-textiles-100616-0414_powdes_ti_f1Those that use the new materials could be used in phones, tablets and other electronic devices, as well as electric vehicles. And because they’re flexible, it could mean a significant development for wearables.

 

 

 

 

 

 

 

 

Technology II: Rice University

391f84fd-6427-4c06-9fb4-3d3c8a433f41A new company has been formed (with exclusive licensing rights) to exploit and commercialize the Next Generation Super-Capacitors and Batteries. The opportunity is based on Nanoporous-Nickel Flexible Thin-form, Scalable Super Capacitors and Si-Nanowire Battery Technologies, developed by Rice University and Dr. James M. Tour, PhD – named “One of the Fifty (50) most influential scientists in the World today” is the inventor, patent holder and early stage developer. tourportrait2015-300

tenka-flex-med-082616-picture1Identified Key Markets and Commercial Applications 

  • Medical Devices and Wearable Electronics
  • Drone/Marine Batteries and Power Banks
  • Powered Smart Cards and Motor Cycle/ EV Batteries
  • Sensors & Power Units for the iOT (Internet of Things) [Flexible Form, Energy Dense]  

 

The Coming Power Needs of the iOTiot-picture1

  • The IoT is populated with billions of tiny devices.
  • They’re smart.
  • They’re cheap.
  • They’re mobile.
  • They need to communicate.
  • Their numbers growing at 20%-30%/Year.

The iOT is Hungry for POWER! All this demands supercapacitors that can pack a lot of affordable power in very small volumes …Ten times more than today’s best supercapacitors can provide.

 

iot-img_0008

 

Highly Scalable – Energy Dense – Flexible Form – Rapid Charge

 Problem 1: Current capacitors and batteries being supplied to the relevant markets lack the sustainable power density, discharge and recharge cycle, warranty life combined with a ‘flexible form factor’ to scale and satisfy the identified industry need for commercial viability & performance.

tenka-smartcard-picture1Solution I: (Minimal Value Product) Tenka is currently providing full, functional Super Capacitor prototypes to an initial customer in the Digital Powered Smart Card industry and has received two (2) phased Contingent Purchase Orders during the First Year Operating Cycle for 120,000 Units and 1,200,000 Units respectively.

Solution II: For Drone/ Marine Batteries – Power Banks & Medical Devices

  • Double the current ‘Time Aloft’ (1 hour+)drone1
  • Reduces operating costs
  • Marine batteries – Less weight, longer life, flex form
  • Provides Fast Recharging,  Extended Life Warranty.
  • Full -battery prototypes being developed

Small batteries will be produced first for Powered Digital Smart Cards (In addition to the MVP Super Caps) solving packaging before scaling up drone battery operations. Technical risks are mainly associated with packaging and scaling.

The Operational Plan is to take full advantage of the gained ‘know how’ (Trade Secrets and Processes) of scaling and packaging solutions developed for the Powered Digital Smart Card and the iOT, to facilitate the roll-out of these additional Application Opportunities. Leveraging gained knowledge from operations is projected to significantly increase margins and profitability. We will begin where the Economies of Scale and Entry Point make sense (cents)!

tenka-mission-082516-picture1

“We are building and Energy Storage Company starting Small & Growing Big!”

Watch the YouTube Video

PEG-PDI, which incorporates a compound long used as a red dye, changes to greenish-blue with the addition of potassium superoxide as it converts the superoxide to dioxygen. Adding more further quenches the reactive oxygen species superoxide, turning the solution purple. Adding hydrogen peroxide in the last step clarifies the liquid, showing that a build-up of excess hydrogen peroxide can deactivate the structure. PEG-PDI, created at Rice University, shows potential as a biological antioxidant. Credit: Tour Group/Rice University

Treated particles of graphene derived from carbon nanotubes have demonstrated remarkable potential as life-saving antioxidants, but as small as they are, something even smaller had to be created to figure out why they work so well.

 

Researchers at Rice University, the McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth) and Baylor College of Medicine created single-molecule compounds that also quench damaging reactive oxygen species (ROS) but are far easier to analyze using standard scientific tools. The molecules may become the basis for new antioxidant therapies in their own right.

The research appears in the American Chemical Society journal ACS Nano.

The original compounds are hydrophilic carbon clusters functionalized with polyethylene glycol, known as PEG-HCCs and created by Rice and Baylor scientists five years ago. The particles help neutralize ROS molecules overexpressed by the body’s cells in response to an injury before they damage cells or cause mutations.

PEG-HCCs show promise for treating cancer, rebooting blood flow in the brain after traumatic injury and controlling chronic diseases.

The new particles, called PEG-PDI, consist of polyethylene glycol and perylene diimide, a compound used as a dye, the color in red car paint and in solar cells for its light-absorbing properties. Their ability to accept electrons from other molecules makes them functionally similar to PEG-HCCs.

They’re close enough to serve as an analog for experiments, according to Rice chemist James Tour, who led the study with University of Texas biochemist Ah-Lim Tsai.

The researchers wrote that the molecule is not only the first example of a small molecular analogue of PEG-HCCs, but also represents the first successful isolation of a PDI radical anion as a single crystal, which allows its structure to be captured with X-ray crystallography.

“This allows us to see the structure of these active particles,” Tour said. “We can get a view of every atom and the distances between them, and get a lot of information about how these molecules quench destructive oxidants in biological tissue.

“Lots of people get crystal structures for stable compounds, but this is a transient intermediate during a catalytic reaction,” he said. “To be able to crystallize a reactive intermediate like that is amazing.”

Antioxidant compounds mimic effective graphene agents, show potential for therapies 



The crystal structure of PEG-PDI is achieved using cobaltocene as a reducing agent and omitting solvents and hydrogen atoms for clarity. Carbon atoms are gray, nitrogens are blue, oxygens red and cobalts purple. The molecules created by scientists at Rice University, the McGovern Medical School at the University of Texas Health Science Center at Houston and Baylor College of Medicine are efficient antioxidants and help scientists understand how larger nanoparticles quench damaging reactive oxygen species in the body. Credit: Tour Group

PEG-HCCs are about 3 nanometers wide and 30 to 40 nanometers long. By comparison, much simpler PEG-PDI molecules are less than a nanometer in width and length.

 

PEG-PDI molecules are true mimics of superoxide dismutase enzymes, protective antioxidants that break down toxic superoxide radicals into harmless molecular oxygen and hydrogen peroxide. The molecules pull electrons from unstable ROS and catalyze their transformation into less-reactive species.

Testing the PEG-PDI molecules can be as simple as putting them in a solution that contains reactive oxygen species molecules like potassium superoxide and watching the solution change color. Further characterization with electron paramagnetic resonance spectroscopy was more complicated, but the fact that it’s even possible makes them powerful tools in resolving mechanistic details, the researchers said.

Tour said adding polyethylene glycol makes the molecules soluble and also increases the amount of time they remain in the bloodstream. “Without PEG, they just go right out of the system through the kidneys,” he said.

When the PEG groups are added, the molecules circulate longer and continue to catalyze reactions.

He said PEG-PDI is just as effective as PEG-HCCs if measured by weight. “Because they have so much more surface area, PEG-HCC particles probably catalyze more parallel reactions per particle,” Tour said. “But if you compare them with PEG-PDI by weight, they are quite similar in total catalytic activity.”

Understanding the structure of PEG-PDI should allow researchers to customize the molecule for applications. “We should have a tremendous ability to modify the molecule’s structure,” he said. “We can add anything we want, exactly where we want, for specific therapies.”

The researchers said PEG-PDI may also be efficient metal- and protein-free catalysts for oxygen reduction reactions used in industry and essential to fuel cells. They are intrinsically more stable than enzymes and can function in much a wider pH range, Tsai said.

Co-author Thomas Kent, a professor of neurology at Baylor who has worked on the project from the start, noted small molecules have a better chance to get on the fast track to approval for therapy by the Food and Drug Administration than nanotube-based agents.
“A small molecule that is not derived from larger nanomaterial may have a better chance of approval to use in humans, assuming it is safe and effective,” he said.

Tour said PEG-PDI serves as a precise model for other graphene derivatives like graphene oxide and permits a more detailed study of graphene-based nanomaterials.

“Making nanomaterials smaller, from well-defined molecules, permits 150 years of synthetic chemistry methods to address the mechanistic questions within nanotechnology,” he said.

 

More information: Almaz S. Jalilov et al. Perylene Diimide as a Precise Graphene-Like Superoxide Dismutase Mimetic, ACS Nano (2017). DOI: 10.1021/acsnano.6b08211

Provided by: Rice University

fracking-happening-1Oil and gas operations in the United States produce about 21 billion barrels of wastewater per year. The saltiness of the water and the organic contaminants it contains have traditionally made treatment difficult and expensive.

 

 

Engineers at the University of Colorado Boulder have invented a simpler process that can simultaneously remove both salts and  from the wastewater, all while producing additional energy. The new technique, which relies on a microbe-powered battery, was recently published in thejournal Environmental Science Water Research & Technology as the cover story.

“The beauty of the technology is that it tackles two different problems in one single system,” said Zhiyong Jason Ren, a CU-Boulder associate professor of environmental and sustainability engineering and senior author of the paper. “The problems become mutually beneficial in our system—they complement each other—and the process produces energy rather than just consumes it.”

The new treatment technology, called microbial capacitive desalination, is like a battery in its basic form, said Casey Forrestal, a CU-Boulder postdoctoral researcher who is the lead author of the paper and working to commercialize the technology. “Instead of the traditional battery, which uses chemicals to generate the electrical current, we use microbes to generate an electrical current that can then be used for desalination.” cu-desal-cell-microbio-c2ee21737f-f1

This microbial electro-chemical approach takes advantage of the fact that the contaminants found in the wastewater contain energy-rich hydrocarbons, the same compounds that make up and. The microbes used in the treatment process eat the hydrocarbons and release their embedded energy. The energy is then used to create a positively charged electrode on one side of the cell and a negatively charged electrode on the other, essentially setting up a battery.

Because salt dissolves into positively and negatively charged ions in water, the cell is then able to remove the salt in the wastewater by attracting the charged ions onto the high-surface-area electrodes, where they adhere.

Not only does the system allow the salt to be removed from the wastewater, but it also creates additional energy that could be used on site to run equipment, the researchers said.

“Right now have to spend energy to treat the wastewater,” Ren said. “We are able to treat it without energy consumption; rather we extract energy out of it.”

Some oil and gas wastewater is currently being treated and reused in the field, but that treatment process typically requires multiple steps—sometimes up to a dozen—and an input of that may come from diesel generators.

Because of the difficulty and expense, wastewater is often disposed of by injecting it deep underground. The need to dispose of wastewater has increased in recent years as the practice of hydraulic fracturing, or “fracking,” has boomed. Fracking refers to the process of injecting a slurry of water, sand and chemicals into wells to increase the amount of oil and natural gas produced by the well.

Injection wells that handle wastewater from fracking operations can cause earthquakes in the region, according to past research by CU-Boulder scientists and others.cu-boulder-maxresdefault

The demand for water for fracking operations also has caused concern among people worried about scarce water resources, especially in arid regions of the country. Finding water to buy for fracking operations in the West, for example, has become increasingly challenging and expensive for oil and gas companies.

Ren and Forrestal’s microbial capacitive desalination cell offers the possibility that water could be more economically treated on site and reused for fracking.

To try to turn the technology into a commercial reality, Ren and Forrestal have co-founded a startup company called BioElectric Inc. In order to determine if the technology offers a viable solution for oil and gas companies, the pair first has to show they can scale up the work they’ve been doing in the lab to a size that would be useful in the field.

The cost to scale up the technology also needs to be competitive with what oil and gas companies are paying now to buy water to use for fracking, Forrestal said. There also is some movement in state legislatures to require oil and gas companies to reuse wastewater, which could make BioElectric’s product more appealing even at a higher price, the researchers said.

mit-gradiantcorp-071715-2MIT – Toward Cheaper Water Treatment for Oil & Gas Operations

MIT spinout makes treating, recycling highly contaminated oilfield water more economical

0629_NEWT-log-lg-310x310Also Read: Nanotechnology Enabled Water Treatment or NEWT: Transforming the Economics of Water Treatment: Rice, ASU, Yale, UTEP win $18.5 Million NSF Engineering Research Center

 

 

 

Explore further: New contaminants found in oil and gas wastewater

More information: “Microbial capacitive desalination for integrated organic matter and salt removal and energy production from unconventional natural gas produced water.” Environ. Sci.: Water Res. Technol., 2015,1, 47-55 DOI: 10.1039/C4EW00050A

gnt-new-thumbnail-2016

Genesis Nanotechnology ~ “Great Things from Small Things”
YouTube Video: Genesis Nanotechnology Nano Enabled Water Treatment; Quantum Dots from Coal & More

graphenequan 033116

 

A Rice University laboratory has found a way to turn common carbon fiber into graphene quantum dots, tiny specks of matter with properties expected to prove useful in electronic, optical and biomedical applications.

The Rice lab of materials scientist Pulickel Ajayan, in collaboration with colleagues in China, India, Japan and the Texas Medical Center, discovered a one-step chemical process that is markedly simpler than established techniques for making  quantum dots. The results were published online this month in the American Chemical Society’s journal Nano Letters.

“There have been several attempts to make graphene-based quantum dots with specific electronic and luminescent properties using chemical breakdown or e-beam lithography of graphene layers,” said Ajayan, Rice’s Benjamin M. and Mary Greenwood Anderson Professor of Mechanical Engineering and Materials Science and of Chemistry. “We thought that as these nanodomains of graphitized carbons already exist in carbon fibers, which are cheap and plenty, why not use them as the precursor?”

Quantum dots, discovered in the 1980s, are semiconductors that contain a size- and shape-dependent . These have been promising structures for applications that range from computers, LEDs, and lasers to medical imaging devices. The sub-5 nanometer carbon-based quantum dots produced in bulk through the wet chemical process discovered at Rice are highly soluble, and their size can be controlled via the temperature at which they’re created.

Graphene quantum dots: The next big small thing
Green-fluorescing graphene quantum dots created at Rice University surround a blue-stained nucleus in a human breast cancer cell. Cells were placed in a solution with the quantum dots for four hours. The dots, each smaller than 5 …more

The Rice researchers were attempting another experiment when they came across the technique. “We tried to selectively oxidize carbon fiber, and we found that was really hard,” said Wei Gao, a Rice graduate student who worked on the project with lead author Juan Peng, a visiting student from Nanjing University who studied in Ajayan’s lab last year. “We ended up with a solution and decided to look at a few drops with a .”

The specks they saw were bits of graphene or, more precisely, oxidized nanodomains of graphene extracted via chemical treatment of carbon fiber. “That was a complete surprise,” Gao said. “We call them quantum dots, but they’re two-dimensional, so what we really have here are graphene quantum discs.” Gao said other techniques are expensive and take weeks to make small batches of graphene quantum dots. “Our starting material is cheap, commercially available . In a one-step treatment, we get a large amount of quantum dots. I think that’s the biggest advantage of our work,” she said.

Graphene quantum dots: The next big small thing
Dark spots on a transmission electron microscope grid are graphene quantum dots made through a wet chemical process at Rice University. The inset is a closeup of one dot. Graphene quantum dots may find use in electronic, optical and …more

Further experimentation revealed interesting bits of information: The size of the dots, and thus their photoluminescent properties, could be controlled through processing at relatively low temperatures, from 80 to 120 degrees Celsius. “At 120, 100 and 80 degrees, we got blue, green and yellow luminescing dots,” she said.

They also found the dots’ edges tended to prefer the form known as zigzag. The edge of a sheet of graphene — the single-atom-thick form of carbon — determines its electrical characteristics, and zigzags are semiconducting.

Their luminescent properties give graphene quantum dots potential for imaging, protein analysis, cell tracking and other , Gao said. Tests at Houston’s MD Anderson Cancer Center and Baylor College of Medicine on two human breast cancer lines showed the dots easily found their way into the cells’ cytoplasm and did not interfere with their proliferation.

“The green quantum dots yielded a very good image,” said co-author Rebeca Romero Aburto, a graduate student in the Ajayan Lab who also studies at MD Anderson. “The advantage of graphene dots over fluorophores is that their fluorescence is more stable and they don’t photobleach. They don’t lose their fluorescence as easily. They have a depth limit, so they may be good for in vitro and in vivo (small animal) studies, but perhaps not optimal for deep tissues in humans.

“But everything has to start in the lab, and these could be an interesting approach to further explore for bioimaging,” Romero Alburto said. “In the future, these graphene could have high impact because they can be conjugated with other entities for sensing applications, too.”

Explore further: Single Atom Quantum Dots Bring Real Devices Closer (Video)

More information: Nano Lett., Article ASAP DOI: 10.1021/nl2038979

Provided by:Rice University

Tour De Ice graphenecomp

Rice University scientists embedded graphene nanoribbon-infused epoxy in a section of helicopter blade to test its ability to remove ice through Joule heating. Credit: Tour Group/Rice University 

A thin coating of graphene nanoribbons in epoxy developed at Rice University has proven effective at melting ice on a helicopter blade.

The coating by the Rice lab of chemist James Tour may be an effective real-time de-icer for aircraft, , transmission lines and other surfaces exposed to winter weather, according to a new paper in the American Chemical Society journal ACS Applied Materials and Interfaces.

In tests, the lab melted centimeter-thick ice from a static helicopter rotor blade in a minus-4-degree Fahrenheit environment. When a small voltage was applied, the coating delivered electrothermal heat – called Joule heating – to the surface, which melted the ice.

The nanoribbons produced commercially by unzipping nanotubes, a process also invented at Rice, are highly conductive. Rather than trying to produce large sheets of expensive graphene, the lab determined years ago that nanoribbons in composites would interconnect and conduct electricity across the material with much lower loadings than traditionally needed.

Previous experiments showed how the nanoribbons in films could be used to de-ice radar domes and even glass, since the films can be transparent to the eye.

Graphene composite may keep wings ice-free
Lab tests at Rice University on a section of a helicopter rotor chilled to minus-4 degrees Fahrenheit show that a thin coat of nanoribbon-infused epoxy can be used as a de-icer. The composite, imbedded between an abrasion shield and the …more

“Applying this composite to wings could save time and money at airports where the glycol-based chemicals now used to de-ice aircraft are also an environmental concern,” Tour said.

In Rice’s lab tests, nanoribbons were no more than 5 percent of the composite. The researchers led by Rice graduate student Abdul-Rahman Raji spread a thin coat of the composite on a segment of rotor blade supplied by a helicopter manufacturer; they then replaced the thermally conductive nickel abrasion sleeve used as a leading edge on . They were able to heat the composite to more than 200 degrees Fahrenheit.

For wings or blades in motion, the thin layer of water that forms first between the heated composite and the surface should be enough to loosen ice and allow it to fall off without having to melt completely, Tour said.

The lab reported that the remained robust in temperatures up to nearly 600 degrees Fahrenheit.

As a bonus, Tour said, the coating may also help protect aircraft from lightning strikes and provide an extra layer of electromagnetic shielding.

Explore further: Researchers create sub-10-nanometer graphene nanoribbon patterns

More information: Abdul-Rahman O. Raji et al. Composites of Graphene Nanoribbon Stacks and Epoxy for Joule Heating and Deicing of Surfaces, ACS Applied Materials & Interfaces (2016). DOI: 10.1021/acsami.5b11131

Published on Dec 3, 2015

Rice University researchers who pioneered the development of laser-induced graphene have configured their discovery into flexible, solid-state microsupercapacitors that rival the best available for energy storage and delivery.

The devices developed in the lab of Rice chemist James Tour are geared toward electronics and apparel. They are the subject of a new paper in the journal Advanced Materials.

Microsupercapacitors are not batteries, but inch closer to them as the technology improves. Traditional capacitors store energy and release it quickly (as in a camera flash), unlike common lithium-ion batteries that take a long time to charge and release their energy as needed.

 

 

Rice Nanoporus Battery 102315 untitledPhoto: Jeff Fitlow

Researchers at Rice University in Houston, Texas, have developed a nanoporous material that has the energy density (the amount of energy stored per unit mass) of an electrochemical battery and the power density (the maximum amount of power that can be supplied per unit mass) of a supercapacitor. It’s important to note that the energy storage device enabled by the material is not claimed to be either of these types of energy storage devices.

The research community has wearied of claims that some new nanomaterial enables a “supercapacitor,” when in fact the energy storage device is not a supercapacitor at all, but a battery. However, in this case, the Rice University researchers, led by James Tour, who is known for having increased the storage capacity of lithium-ion (Li-ion) batteries with graphene, don’t make any claims that the device they created is a supercapacitor. Instead it is described as an electrochemical capacitor with nanoporous nickel-fluoride electrodes layered around a solid electrolyte that is flexible and relatively easy to scale up for manufacturing.Rice logo_rice3

The issue of appropriate nomenclature aside, the reported performance figures for this energy storage material are very attractive. In the Journal of the American Chemical Society (“Flexible Three-Dimensional Nanoporous Metal-Based Energy Devices“),  the researchers report energy density of 384 watt-hours per kilogram (Wh/kg), and power density of 112 kilowatts per kilogram (kW/kg).

To give some context to these numbers, a typical energy density for a Li-ion battery is 200Wh/kg, whereas commercially available supercapacitors store around 5- to 25 Wh/kg and research prototype supercapacitors have made claims of anywhere from 85 to 164 Wh/kg. In terms of power density, the numbers for the new nanoporous material is in line with those of supercapacitors, which range from 10 to 100 kW/kg—far higher than the 0.005 to 0.4kW/kg that batteries can deliver.

“The numbers are exceedingly high in the power that it can deliver, and it’s a very simple method to make high-powered systems,” Tour said in a press release. “We’re already talking with companies interested in commercializing this.”

To make the battery-supercapacitor hybrid, the Rice team deposited a nickel layer on a backing material. They then etched the nickel layer to create pores five nanometers in diameter. The result is high surface area for storing ions. After removing the backing, the nickel-based electrode material is wrapped around a solid electrolyte of potassium hyrodroxide in polyvinyl alcohol. In testing, the researchers found that there was no degradation of the pore structure after 10 000 charge-discharge cycles, or any significant degradation of the electrode-electrolyte interface.

“Compared with a lithium-ion device, the structure is quite simple and safe,” said Yang Yang, lead author of the paper, in the press release. “It behaves like a battery but the structure is that of a supercapacitor. If we use it as a supercapacitor, we can charge quickly at a high current rate and discharge it in a very short time. But for other applications, we find we can set it up to charge more slowly and to discharge slowly like a battery.”

With the device’s flexibility and high charge-up rate, it’s possible to imagine this storage device powering flexible mobile devices. However, charging rates for the battery/supercapacitor will be limited by the typical 200-amp 240V single-phase residential service, which is only capable of providing (absent any other load) only 48 kW.

Rice Pillard Graphene 0914_HYBRID-1-WEBx250Rice Univ. researchers discovered that putting nanotube pillars between sheets of graphene could create hybrid structures with a unique balance of strength, toughness and ductility throughout all three dimensions.

Carbon nanomaterials are common now as flat sheets, nanotubes and spheres, and they’re being eyed for use as building blocks in hybrid structures with unique properties for electronics, heat transport and strength. The Rice team is laying a theoretical foundation for such structures by analyzing how the blocks’ junctions influence the properties of the desired materials.

Rice materials scientist Rouzbeh Shahsavari and alumnus Navid Sakhavand calculated how various links, particularly between carbon nanotubes and graphene, would affect the final hybrid’s properties in all directions. They found that introducing junctions would add extra flexibility while maintaining almost the same strength when compared with materials made of layered graphene.

Their results appear in Carbon.

Carbon nanotubes are rolled-up arrays of perfect hexagons of atoms; graphene is a rolled-out sheet of the same. Both are super-strong and excel at transmitting electrons and heat. But when the two are joined, the way the atoms are arranged can influence all those properties.

Rice Pillard Graphene 0914_HYBRID-1-WEBx250

Carbon nanotube pillars between sheets of graphene may create hybrid structures with a unique balance of strength, toughness and ductility throughout all three dimensions, according to Rice Univ. scientists. Five, seven or eight-atom rings at the junctions can force the graphene to wrinkle. Image: Shuo Zhao and Lei Tao/Rice Univ.

“Some labs are actively trying to make these materials or measure properties like the strength of single nanotubes and graphene sheets,” Shahsavari said. “But we want to see what happens and quantitatively predict the properties of hybrid versions of graphene and nanotubes. These hybrid structures impart new properties and functionality that are absent in their parent structures—graphene and nanotubes.”

To that end, the lab assembled three-dimensional computer models of “pillared graphene nanostructures,” akin to the boron-nitride structures modeled in a previous study to analyze heat transfer between layers.

“This time we were interested in a comprehensive understanding of the elastic and inelastic properties of 3-D carbon materials to test their mechanical strength and deformation mechanisms,” Shahsavari said. “We compared our 3-D hybrid structures with the properties of 2-D stacked graphene sheets and 1-D carbon nanotubes.”

Layered sheets of graphene keep their properties in-plane, but exhibit little stiffness or thermal conductance from sheet to sheet, he said. But pillared graphene models showed far better strength and stiffness and a 42 percent improvement in out-of-plane ductility, the ability to deform under stress without breaking. The latter allows pillared graphene to exhibit remarkable toughness along out-of-plane directions, a feature that is not possible in 2-D stacked graphene sheets or 1-D carbon nanotubes, Shahsavari said.

The researchers calculated how the atoms’ inherent energies force hexagons to take on or lose atoms to neighboring rings, depending on how they join with their neighbors. By forcing five, seven or even eight-atom rings, they found they could gain a measure of control over the hybrid’s mechanical properties. Turning the nanotubes in a way that forced wrinkles in the graphene sheets added further flexibility and shear compliance, Shahsavari said.

When the material did fracture, the researchers found it far more likely for this to happen at the eight-member rings, where much of the strain gathers when stressed. That leads to the notion the hybrids can be tuned to fail under particular circumstances.

“This is the first time anyone has created such a comprehensive atomistic ‘lens’ to look at the junction-mediated properties of 3-D carbon nanomaterials,” Shahsavari said. “We believe the principles can be applied to other low-dimensional materials such as boron nitride and molybdenum/tungsten or the combinations thereof.”

Source: Rice Univ.

riceresearch Solar Water Split 090415Rice University researchers have demonstrated an efficient new way to capture the energy from sunlight and convert it into clean, renewable energy by splitting water molecules.

The technology, which is described online in the American Chemical Society journal Nano Letters, relies on a configuration of light-activated gold nanoparticles that harvest sunlight and transfer solar energy to highly excited electrons, which scientists sometimes refer to as “hot electrons.”

“Hot electrons have the potential to drive very useful chemical reactions, but they decay very rapidly, and people have struggled to harness their energy,” said lead researcher Isabell Thomann, assistant professor of electrical and computer engineering and of chemistry and materials science and nanoengineering at Rice. “For example, most of the energy losses in today’s best photovoltaic solar panels are the result of hot electrons that cool within a few trillionths of a second and release their energy as wasted heat.”

Capturing these high-energy electrons before they cool could allow solar-energy providers to significantly increase their solar-to-electric power-conversion efficiencies and meet a national goal of reducing the cost of solar electricity.

In the light-activated nanoparticles studied by Thomann and colleagues at Rice’s Laboratory for Nanophotonics (LANP), light is captured and converted into plasmons, waves of electrons that flow like a fluid across the metal surface of the nanoparticles. Plasmons are high-energy states that are short-lived, but researchers at Rice and elsewhere have found ways to capture plasmonic energy and convert it into useful heat or light. Plasmonic nanoparticles also offer one of the most promising means of harnessing the power of hot electrons, and LANP researchers have made progress toward that goal in several recent studies.

riceresearch Solar Water Split 090415

Rice University researchers have demonstrated an efficient new way to capture the energy from sunlight and convert it into clean, renewable energy by splitting water molecules. Credit: I. Thomann/Rice University 

Thomann and her team, graduate students Hossein Robatjazi, Shah Mohammad Bahauddin and Chloe Doiron, created a system that uses the energy from hot electrons to split molecules of water into oxygen and hydrogen. That’s important because oxygen and hydrogen are the feedstocks for fuel cells, electrochemical devices that produce electricity cleanly and efficiently.

To use the hot electrons, Thomann’s team first had to find a way to separate them from their corresponding “electron holes,” the low-energy states that the hot electrons vacated when they received their plasmonic jolt of energy. One reason hot electrons are so short-lived is that they have a strong tendency to release their newfound energy and revert to their low-energy state. The only way to avoid this is to engineer a system where the hot electrons and electron holes are rapidly separated from one another. The standard way for electrical engineers to do this is to drive the hot electrons over an energy barrier that acts like a one-way valve. Thomann said this approach has inherent inefficiencies, but it is attractive to engineers because it uses well-understood technology called Schottky barriers, a tried-and-true component of electrical engineering.


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