Scientists develop Lithium Metal batteries that charge faster, last longer with 10X times more energy by volume than Li-Ion Batteries – BIG potential for Our EV / AV Future


October 25, 2018

Rice University scientists are counting on films of carbon nanotubes to make high-powered, fast-charging lithium metal batteries a logical replacement for common lithium-ion batteries.

The Rice lab of chemist James Tour showed thin nanotube films effectively stop dendrites that grow naturally from unprotected lithium metal anodes in batteries. Over time, these tentacle-like dendrites can pierce the battery’s electrolyte core and reach the cathode, causing the battery to fail.

That problem has both dampened the use of lithium metal in commercial applications and encouraged researchers worldwide to solve it.

img_0837-1Rice University graduate student Gladys López-Silva holds a lithium metal anode with a film of carbon nanotubes. Once the film is attached, it becomes infiltrated by lithium ions and turns red. Photo by Jeff Fitlow

Lithium metal charges much faster and holds about 10 times more energy by volume than the lithium-ion electrodes found in just about every electronic device, including cellphones and electric cars.



MIT NEWS: Read More About Lithium Metal Batteries

“One of the ways to slow dendrites in lithium-ion batteries is to limit how fast they charge,” Tour said. “People don’t like that. They want to be able to charge their batteries quickly.”

The Rice team’s answer, detailed in Advanced Materials, is simple, inexpensive and highly effective at stopping dendrite growth, Tour said.

“What we’ve done turns out to be really easy,” he said. “You just coat a lithium metal foil with a multiwalled carbon nanotube film. The lithium dopes the nanotube film, which turns from black to red, and the film in turn diffuses the lithium ions.”

“Physical contact with lithium metal reduces the nanotube film, but balances it by adding lithium ions,” said Rice postdoctoral researcher Rodrigo Salvatierra, co-lead author of the paper with graduate student Gladys López-Silva. “The ions distribute themselves throughout the nanotube film.”

img_0835An illustration shows how lithium metal anodes developed at Rice University are protected from dendrite growth by a film of carbon nanotubes. Courtesy of the Tour Group

When the battery is in use, the film discharges stored ions and the underlying lithium anode refills it, maintaining the film’s ability to stop dendrite growth.

The tangled-nanotube film effectively quenched dendrites over 580 charge/discharge cycles of a test battery with a sulfurized-carbon cathode the lab developed in previous experiments.

The researchers reported the full lithium metal cells retained 99.8 percent of their coulombic efficiency, the measure of how well electrons move within an electrochemical system.

1028_DENDRITE-3-rn-1plyhun (1)

Rice University scientists have discovered that a film of multiwalled carbon nanotubes quenches the growth of dendrites in lithium metal-based batteries. Courtesy of the Tour Group

Co-authors of the paper are Rice alumni Almaz Jalilov of the King Fahd University of Petroleum and Minerals, Saudi Arabia; Jongwon Yoon, a senior researcher at the Korea Basic Science Institute; and Gang Wu, an instructor, and Ah-Lim Tsai, a professor of hematology, both at the McGovern Medical School at the University of Texas Health Science Center at Houston.

Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of computer science and of materials science and nanoengineering at Rice.

The research was supported by the Air Force Office of Scientific Research, the National Institutes of Health, the National Council of Science and Technology, Mexico; the National Council for Scientific and Technological Development, Ministry of Science, Technology and Innovation and Coordination for the Improvement of Higher Education Personnel, Brazil; and Celgard, LLC.

1028_DENDRITE-5-rn-18fsg2wRice University chemist James Tour, left, graduate student Gladys López-Silva and postdoctoral researcher Rodrigo Salvatierra use a film of carbon nanotubes to prevent dendrite growth in lithium metal batteries, which charge faster and hold more power than current lithium-ion batteries. Photo by Jeff Fitlow.

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Rice University: NEWT (Nano Enabled Water Treatment) Reusable water-treatment particles effectively eliminate BPA

Rice U reusablewate water
Rice University researchers have enhanced micron-sized titanium dioxide particles to trap and destroy BPA, a water contaminant with health implications. Cyclodextrin molecules on the surface trap BPA, which is then degraded by reactive …more

Rice University scientists have developed something akin to the Venus’ flytrap of particles for water remediation.

The research is detailed in the American Chemical Society journal Environmental Science & Technology.

BPA is commonly used to coat the insides of food cans, bottle tops and  supply lines, and was once a component of baby bottles. While BPA that seeps into food and drink is considered safe in low doses, prolonged exposure is suspected of affecting the health of children and contributing to high blood pressure.

The good news is that reactive oxygen species (ROS) – in this case, hydroxyl radicals – are bad news for BPA. Inexpensive titanium dioxide releases ROS when triggered by ultraviolet light. But because oxi-dating molecules fade quickly, BPA has to be close enough to attack.

That’s where the trap comes in.

Close up, the spheres reveal themselves as flower-like collections of titanium dioxide petals. The supple petals provide plenty of surface area for the Rice researchers to anchor cyclodextrin molecules.

Reusable water-treatment particles effectively eliminate BPA
“Petals” of a titanium dioxide sphere enhanced with cyclodextrin as seen under a scanning electron microscope. When triggered by ultraviolet light, the spheres created at Rice University are effective at removing bisphenol A contaminants from water. Credit: Alvarez Lab

Cyclodextrin is a benign sugar-based molecule often used in food and drugs. It has a two-faced structure, with a hydrophobic (water-avoiding) cavity and a hydrophilic (water-attracting) outer surface. BPA is also hydrophobic and naturally attracted to the cavity. Once trapped, ROS produced by the spheres degrades BPA into harmless chemicals.

In the lab, the researchers determined that 200 milligrams of the spheres per liter of contaminated water degraded 90 percent of BPA in an hour, a process that would take more than twice as long with unenhanced titanium dioxide.

0629_NEWT-log-lg-310x310The work fits into technologies developed by the Rice-based and National Science Foundation-supported Center for Nanotechnology-Enabled Water Treatment because the spheres self-assemble from titanium dioxide nanosheets.

“Most of the processes reported in the literature involve nanoparticles,” said Rice graduate student and lead author Danning Zhang. “The size of the particles is less than 100 nanometers. Because of their very small size, they’re very difficult to recover from suspension in water.”

The Rice particles are much larger. Where a 100-nanometer particle is 1,000 times smaller than a human hair, the enhanced  is between 3 and 5 microns, only about 20 times smaller than the same hair. “That means we can use low-pressure microfiltration with a membrane to get these particles back for reuse,” Zhang said. “It saves a lot of energy.”
Reusable water-treatment particles effectively eliminate BPA
Rice graduate student Danning Zhang, who led the development of a particle that attracts and degrades contaminants in water, checks a sample in a Rice environmental lab. Credit: Jeff Fitlow

Because ROS also wears down cyclodextrin, the spheres begin to lose their trapping ability after about 400 hours of continued ultraviolet exposure, Zhang said. But once recovered, they can be easily recharged.

“This new material helps overcome two significant technological barriers for photocatalytic water treatment,” Alvarez said. “First, it enhances treatment efficiency by minimizing scavenging of ROS by non-target constituents in water. Here, the ROS are mainly used to destroy BPA.

“Second, it enables low-cost separation and reuse of the catalyst, contributing to lower treatment cost,” he said. “This is an example of how advanced materials can help convert academic hypes into feasible processes that enhance water security.”

 Explore further: Mat baits, hooks and destroys pollutants in water

More information: Danning Zhang et al. Easily-recoverable, micron-sized TiO2 hierarchical spheres decorated with cyclodextrin for enhanced photocatalytic degradation of organic micropollutants, Environmental Science & Technology (2018). DOI: 10.1021/acs.est.8b04301


Our Bioelectronic Future: Smaller, Smarter, Connected – De Lange Conference at Rice University: Video

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Bioelectronics, Our Bioelectronic Future: Smaller, Smarter, Connected

De Lange Conference XI | December 4-5, 2018 | Rice University De Lange Conference XI will bring together biologists, engineers, medical researchers, policy scholars, humanists, and industrial representatives from the nascent bioelectronics industry and federal agencies will serve to identify the grand challenges in the field, including technological, ethical, legal, and societal issues. The biennial De Lange Conferences, funded by the De Lange Endowment, were established by C.M. and Demaris Hudspeth in honor of Demaris’ parents, Albert and Demaris De Lange. For more information, visit


Read More About Graphene Applications for Bio-Electronics and Neuroprosthetics

Graphene Bioelectrics id50987_1The term bioelectronics, or bionics for short, describes a research field that is concerned with the integration of biological components with electronics; specifically, the application of biological materials and processes in electronics, and the use of electronic devices in living systems.
One day, bionics research could result in neural prostheses that augment or restore damaged or lost functions of the nervous system – restore vision, healing spinal cord injuries, and ameliorate neurodegenerative diseases such as Parkinson’s.

Rice University engineers develop system to remove contaminants from water


Engineer Qilin Li at Rice University’s lab is building a treatment system that can be tuned to selectively pull toxins from wastewater from factories, sewage systems and oil and gas wells, as well as drinking water. The researchers said their technology will cut costs and save energy compared to conventional systems.

“Traditional methods to remove everything, such as reverse osmosis, are expensive and energy intensive,” said Li, the lead scientist and co-author of a study about the new technology in the American Chemical Society journal Environmental Science & Technology. “If we figure out a way to just fish out these minor components, we can save a lot of energy.”

The heart of Rice’s system is a set of novel composite electrodes that enable capacitive deionization. The charged, porous electrodes selectively pull target ions from fluids passing through the maze-like system. When the pores get filled with toxins, the electrodes can be cleaned, restored to their original capacity and reused.

“This is part of a broad scope of research to figure out ways to selectively remove ionic contaminants,” said Li, a professor of civil and environmental engineering and of materials science and nanoengineering. “There are a lot of ions in water. Not everything is toxic. For example, sodium chloride (salt) is perfectly benign. We don’t have to remove it unless the concentration gets too high.”

In tests, an engineered coating of resin, polymer and activated carbon removed and trapped harmful sulfate ions, and other coatings can be used in the same platform to target other contaminants. Illustration by Kuichang Zuo

The proof-of-principal system developed by Li’s team removed sulfate ions. The system’s electrodes were coated with activated carbon, which was in turn coated by a thin film of tiny resin particles held together by quaternized polyvinyl alcohol. When sulfate-contaminated water flowed through a channel between the charged electrodes, sulfate ions were attracted by the electrodes, passed through the resin coating and stuck to the carbon. Tests in the Rice lab showed the positively charged coating on the cathode preferentially captured sulfate ions over salt at a ratio of more than 20 to 1. The electrodes retained their properties over 50 cycles. “But in fact, in the lab, we’ve run the system for several hundred cycles and I don’t see any breaking or peeling of the material,” said Kuichang Zuo, lead author of the paper and a postdoctoral researcher in Li’s lab. “It’s very robust.”

In Rice’s new water-treatment platform, electrode coatings can be swapped out to allow the device to selectively remove a range of contaminants from wastewater, drinking water and industrial fluids. Illustration by Kuichang Zuo

“The true merit of this work is not that we were able to selectively remove sulfate, because there are many other contaminants that are perhaps more important,” she said. “The merit is that we developed a technology platform that we can use to target other contaminants as well by varying the composition of the electrode coating.”

The research was supported by the Rice-based National Science Foundation-backed Center for Nanotechnology-Enabled Water Treatment, the Welch Foundation and the Shanghai Municipal International Cooperation Foundation.

Nidec Motor Corp. appoints CEO

Nidec Motor Corporation (NMC) named Henk van Duijnhoven as its CEO and global business leader of ACIM (Appliances, Commercial and Industrial Motors). Van Duijnhoven was most recently a partner and managing director of The Boston Consulting Group where he was responsible for business turnaround, mergers and acquisitions, and strategy planning for clients in the industrial and medtech markets. He holds a Bachelor of Science degree from the College of Automotive Engineering and a Master of Business Administration from the Massachusetts Institute of Technology.

Woodard & Curran names new business unit leader

Woodard & Curran named Peter Nangeroni as its new industrial and commercial strategic business unit leader. He brings experience managing large, multidisciplinary projects for industrial clients with emphasis on generating positive environmental outcomes, return on investment and improved risk management. He has been with Woodard & Curran for 13 years in various roles, most recently as director of technical practices. He takes over for the long-time leader of the business unit, Mike Curato, who is retiring after 11 years in the role and 20 with the firm.

Nangeroni is a Professional Engineer with a degree in civil engineering from Tufts University and more than 35 years of experience working with clients on engineering and construction management projects. In his new role, he will oversee staffing, business development and project execution at a strategic level for the industrial and commercial strategic business unit, which focuses on water treatment, manufacturing and process utilities for clients in a wide range of industrial sectors.

Rice University: Nanotubes change the shape of water

nanotubeschange water Rice UMolecular models of nanotube ice produced by engineers at Rice University show how forces inside a carbon nanotube at left and a boron nitride nanotube at right pressure water molecules into taking on the shape of a square tube. The …more

First, according to Rice University engineers, get a nanotube hole. Then insert water. If the nanotube is just the right width, the water molecules will align into a square rod.

Rice materials scientist Rouzbeh Shahsavari and his team used molecular models to demonstrate their theory that weak van der Waals forces between the inner surface of the nanotube and the  are strong enough to snap the oxygen and hydrogen atoms into place.

Shahsavari referred to the contents as two-dimensional “ice,” because the  freeze regardless of the temperature. He said the research provides valuable insight on ways to leverage atomic interactions between nanotubes and  molecules to fabricate nanochannels and energy-storing nanocapacitors.

A paper on the research appears in the American Chemical Society journal Langmuir.

Shahsavari and his colleagues built molecular models of carbon and  with adjustable widths. They discovered boron nitride is best at constraining the shape of water when the nanotubes are 10.5 angstroms wide. (One angstrom is one hundred-millionth of a centimeter.)

The researchers already knew that  in tightly confined water take on interesting structural properties. Recent experiments by other labs showed strong evidence for the formation of nanotube ice and prompted the researchers to build density functional theory models to analyze the forces responsible.

Shahsavari’s team modeled water molecules, which are about 3 angstroms wide, inside carbon and boron nitride nanotubes of various chiralities (the angles of their atomic lattices) and between 8 and 12 angstroms in diameter. They discovered that nanotubes in the middle diameters had the most impact on the balance between molecular interactions and van der Waals pressure that prompted the transition from a square water tube to ice.

“If the nanotube is too small and you can only fit one water molecule, you can’t judge much,” Shahsavari said. “If it’s too large, the water keeps its amorphous shape. But at about 8 angstroms, the nanotubes’ van der Waals force starts to push water molecules into organized square shapes.”

He said the strongest interactions were found in boron nitride  due to the particular polarization of their atoms.

Shahsavari said nanotube ice could find use in molecular machines or as nanoscale capillaries, or foster ways to deliver a few molecules of water or sequestered drugs to targeted cells, like a nanoscale syringe.

 Explore further: Scientists say boron nitride-graphene hybrid may be right for next-gen green cars

More information: Farzaneh Shayeganfar et al, First Principles Study of Water Nanotubes Captured Inside Carbon/Boron Nitride Nanotubes, Langmuir (2018). DOI: 10.1021/acs.langmuir.8b00856

Is This the Battery Boost We’ve Been Waiting For?

electric-car_technology_of-100599537-primary.idgeElectric cars are among the products that stand to benefit from new lithium-ion cells that could store as much as 40% more energy. A BMW i Vision Dynamics concept electric automobile, made by BMW AG, on display in September. PHOTO: SIMON DAWSON/BLOOMBERG

The batteries that power our modern world—from phones to dronesto electric cars—will soon experience something not heard of in years: Their capacity to store electricity will jump by double-digit percentages, according to researchers, developers and manufacturers.

The next wave of batteries, long in the pipeline, is ready for commercialization. This will mean, among other things, phones with 10% to 30% more battery life, or phones with the same battery life but faster and lighter or with brighter screens. We’ll see more cellular-connected wearables. As this technology becomes widespread, makers of electric vehicles and home storage batteries will be able to knock thousands of dollars off their prices over the next five to 10 years. Makers of electric aircraft will be able to explore new designs.

There is a limit to how far lithium-ion batteries can take us; surprisingly, it’s about twice their current capacity. The small, single-digit percentage improvements we see year after year typically are because of improvements in how they are made, such as small tweaks to their chemistry or new techniques for filling battery cells with lithium-rich electrolyte. What’s coming is a more fundamental change to the materials that make up a battery.

Equipment that Sila Nanotechnologies uses to manufacture material for lithium-silicon batteries.
Equipment that Sila Nanotechnologies uses to manufacture material for lithium-silicon batteries. PHOTO: SILA NANOTECHNOLOGIES


First, some science: Every lithium-ion battery has an anode and a cathode. Lithium ions traveling between them yield the electrical current that powers our devices. When a battery is fully charged, the anode has sucked up lithium ions like a sponge. And as it discharges, those ions travel through the electrolyte, to the cathode.

Typically, anodes in lithium-ion batteries are made of graphite, which is carbon in a crystalline form. While graphite anodes hold a substantial number of lithium ions, researchers have long known a different material, silicon, can hold 25 times as many.

The trick is, silicon brings with it countless technical challenges. For instance, a pure silicon anode will soak up so many lithium ions that it gets “pulverized” after a single charge, says George Crabtree, director of the Joint Center for Energy Storage Research, established by the U.S. Department of Energy at the University of Chicago Argonne lab to accelerate battery research.

Current battery anodes can have small amounts of silicon, boosting their performance slightly. The amount of silicon in a company’s battery is a closely held trade secret, but Dr. Crabtree estimates that in any battery, silicon is at most 10% of the anode. In 2015, Tesla founder Elon Musk revealed that silicon in the Panasonic-made batteries of the auto maker’s Model S helped boost the car’s range by 6%.

Now, some startups say they are developing production-ready batteries with anodes that are mostly silicon. Sila Nanotechnologies,Angstron Materials , Enovix and Enevate, to name a few, offer materials for so-called lithium-silicon batteries, which are being tested by the world’s largest battery manufacturers, car companies and consumer-electronics companies.

Prototype batteries built at Sila with the startup's silicon-dominant anode technology.
Prototype batteries built at Sila with the startup’s silicon-dominant anode technology. PHOTO: SILA NANOTECHNOLOGIES

For Sila, in Alameda, Calif., the secret is nanoparticles lots of empty space inside. This way, the lithium can be absorbed into the particle without making the anode swell and shatter, says Sila Chief Executive Gene Berdichevsky. Cells made with Sila’s particles could store 20% to 40% more energy, he adds.

Angstron Materials, in Dayton, Ohio, makes similar claims about its nanoparticles for lithium-ion batteries.

Dr. Crabtree says this approach is entirely plausible, though there’s a trade-off: By allowing more room inside the anode for lithium ions, manufacturers must produce a larger anode. This anode takes up more space in the battery, allowing less overall space to increase capacity. This is why the upper bound of increased energy density using this approach is about 40%.

The big challenge, as ever, is getting to market, says Dr. Crabtree.

Sila’s clients include BMW and Amperex Technology , one of the world’s largest makers of batteries for consumer electronics, including both Apple ’s iPhone and Samsung ’s Galaxy S8 phone.

China-based Amperex is also an investor in Sila, but Amperex Chief Operating Officer Joe Kit Chu Lam says his company is securing several suppliers of the nanoparticles necessary to produce lithium-silicon batteries. Having multiple suppliers is essential for securing enough volume, he says.

This nanoparticle of carbon and silicon, made by Global Graphene Group, could help lithium-ion batteries store significantly more energy.
This nanoparticle of carbon and silicon, made by Global Graphene Group, could help lithium-ion batteries store significantly more energy. PHOTO: GLOBAL GRAPHENE GROUP

The first commercial consumer devices to have higher-capacity lithium-silicon batteries will likely be announced in the next two years, says Mr. Lam, who expects a wearable to be first. Other companies claim a similar timetable for consumer rollout.

Enevate produces complete silicon-dominant anodes for car manufacturers. CEO Robert Rango says its technology increases the range of electric vehicles by 30% compared with conventional lithium-ion batteries.

BMW plans to incorporate Sila’s silicon anode technology in a plug-in electric vehicle by 2023, says a company spokesman. BMW expects an increase of 10% to 15% in battery-pack capacity in a single leap. While this is the same technology destined for mobile electronics, the higher volumes and higher safety demands of the auto industry mean slower implementation there. In 2017, BMW said it would invest €200 million ($246 million) in its own battery-research center.

Enovix, whose investors include Intel and Qualcomm, has pioneered a different kind of 3-D structure for its batteries, says CEO Harrold Rust. With much higher energy density and anodes that are almost pure silicon, the company claims its batteries would contain 30% to 50% more energy in the size needed for a mobile phone, and two to three times as much in the size required for a smartwatch.

The downside: producing these will require a significant departure from the current manufacturing process.

Even though it’s a significant advance, to get beyond what’s possible with lithium-silicon batteries will require a change in battery composition—such as lithium-sulfur chemistry or solid-state batteries. Efforts to make these technologies viable are at a much earlier stage, however, and it isn’t clear when they’ll arrive.

Meanwhile, we can look forward to the possibility of a thinner or more capable Apple Watch, wireless headphones we don’t have to charge as often and electric vehicles that are actually affordable. The capacity of lithium-ion batteries has increased threefold since their introduction in 1991, and at every level of improvement, new and unexpected applications, devices and business opportunities pop up.


Corrections & Amplifications 

Sila Nanotechnologies produces nanoparticles that contain silicon and other components, but don’t include graphite. A previous version of this column incorrectly described nanoparticles as a graphite-silicon composite. An earlier version also incorrectly identified Angstron Materials as Angstrom Materials. (Angstron error corrected: March 18, 2018. Nanoparticles error corrected: March 19, 2018


Appeared in the March 19, 2018, print edition as ‘Battery Life Powers Ahead Toward Sizable Gains.’

Have you seen Tenka Energy’s YouTube Video?  Watch Here:

NEWT – Mat baits, hooks and destroys pollutants in water: Rice University

Specks of titanium dioxide adhere to polyvinyl fibers in a mat developed at the Rice University-led NEWT Center to capture and destroy pollutants from wastewater or drinking water. After the mat attracts and binds pollutants, the titanium dioxide photocatalyst releases reactive oxygen species that destroy them. Credit: Rice University/NEWT

A polymer mat developed at Rice University has the ability to fish biologically harmful contaminants from water through a strategy known as “bait, hook and destroy.”

Tests with wastewater showed the mat can efficiently remove targeted pollutants, in this case a pair of biologically harmful endocrine disruptors, using a fraction of the energy required by other technology. The technique can also be used to treat drinking water.

The mat was developed by scientists with the Rice-led Nanotechnology-Enabled Water Treatment (NEWT) Center. The research is available online in the American Chemical Society journal Environmental Science and Technology.

The mat depends on the ability of a common material, titanium dioxide, to capture pollutants and, upon exposure to light, degrade them through oxidation into harmless byproducts.

Titanium dioxide is already used in some wastewater treatment systems. It is usually turned into a slurry, combined with wastewater and exposed to ultraviolet light to destroy contaminants. The slurry must then be filtered from the water.

The NEWT mat simplifies the process. The mat is made of spun polyvinyl fibers. The researchers made it highly porous by adding small plastic beads that were later dissolved with chemicals. The pores offer plenty of surface area for titanium oxide particles to inhabit and await their prey.

The mat’s hydrophobic (water-avoiding) fibers naturally attract hydrophobic contaminants like the endocrine disruptors used in the tests. Once bound to the mat, exposure to light activates the photocatalytic titanium dioxide, which produces reactive oxygen species (ROS) that destroy the contaminants.

Established by the National Science Foundation in 2015, NEWT is a national research center that aims to develop compact, mobile, off-grid water-treatment systems that can provide clean water to millions of people who lack it and make U.S. energy production more sustainable and cost-effective.

NEWT researchers said their mat can be cleaned and reused, scaled to any size, and its chemistry can be tuned for various pollutants.

“Current photocatalytic treatment suffers from two limitations,” said Rice environmental engineer and NEWT Center Director Pedro Alvarez. “One is inefficiency because the oxidants produced are scavenged by things that are much more abundant than the target pollutant, so they don’t destroy the pollutant.

The Rice University-led NEWT Center created a nanoparticle-infused polymer mat that both attracts and destroys pollutants in wastewater or drinking water. A mat, top left, is immersed in water with methylene blue as a contaminant. The contaminant is then absorbed at top right by the mat and, in the bottom images, destroyed by exposure to light. The mat is then ready for reuse. Credit: Rice University/NEWT

“Second, it costs a lot of money to retain and separate slurry photocatalysts and prevent them from leaking into the treated water,” he said. “In some cases, the energy cost of filtering that slurry is more than what’s needed to power the UV lights.

“We solved both limitations by immobilizing the catalyst to make it very easy to reuse and retain,” Alvarez said. “We don’t allow it to leach out of the mat and impact the water.”

Alvarez said the porous polymer mat plays an important role because it attracts the target pollutants. “That’s the bait and hook,” he said. “Then the photocatalyst destroys the pollutant by producing hydroxyl radicals.”

“The nanoscale pores are introduced by dissolving a sacrificial polymer on the electrospun fibers,” lead author and former Rice postdoctoral researcher Chang-Gu Lee said. “The pores enhance the contaminants’ access to titanium dioxide.”

The experiments showed dramatic energy reduction compared to wastewater treatment using slurry.

“Not only do we destroy the pollutants faster, but we also significantly decrease our electrical energy per order of reaction,” Alvarez said. “This is a measure of how much energy you need to remove one order of magnitude of the pollutant, how many kilowatt hours you need to remove 90 percent or 99 percent or 99.9 percent.

“We show that for the slurry, as you move from treating distilled water to wastewater treatment plant effluent, the amount of energy required increases 11-fold. But when you do this with our immobilized bait-and-hook photocatalyst, the comparable increase is only two-fold. It’s a significant savings.”

The mat also would allow treatment plants to perform pollutant removal and destruction in two discrete steps, which isn’t possible with the slurry, Alvarez said. “It can be desirable to do that if the water is murky and light penetration is a challenge. You can fish out the contaminants adsorbed by the mat and transfer it to another reactor with clearer water. There, you can destroy the pollutants, clean out the mat and then return it so it can fish for more.”

Tuning the mat would involve changing its hydrophobic or hydrophilic properties to match target pollutants. “That way you could treat more water with a smaller reactor that is more selective, and therefore miniaturize these reactors and reduce their carbon footprints,” he said. “It’s an opportunity not only to reduce energy requirements, but also space requirements for photocatalytic water treatment.”

Alvarez said collaboration by NEWT’s research partners helped the project come together in a matter of months. “NEWT allowed us to do something that separately would have been very difficult to accomplish in this short amount of time,” he said.

“I think the mat will significantly enhance the menu from which we select solutions to our water purification challenges,” Alvarez said.

More information: Chang-Gu Lee et al, Porous electrospun fibers embedding TiO2 for adsorption and photocatalytic degradation of water pollutants, Environmental Science & Technology (2018). DOI: 10.1021/acs.est.7b06508

Provided by Rice University

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Rice University Expands LIG (laser induced graphene) Research and Applications: Supercapacitor, an Electrocatalyst for Fuel Cells, RFID’s and Biological Sensors


Rice University scientists who introduced laser-induced graphene (LIG) have enhanced their technique to produce what may become a new class of edible electronics.

The Rice lab of chemist James Tour, which once turned Girl Scout cookies into graphene, is investigating ways to write graphene patterns onto food and other materials to quickly embed conductive identification tags and sensors into the products themselves.

“This is not ink,” Tour said. “This is taking the material itself and converting it into graphene.”

The process is an extension of the Tour lab’s contention that anything with the proper carbon content can be turned into graphene. In recent years, the lab has developed and expanded upon its method to make graphene foam by using a commercial laser to transform the top layer of an inexpensive polymer film.


Laser-Induced graphene supercapacitors may be the future of wearables

The foam consists of microscopic, cross-linked flakes of graphene, the two-dimensional form of carbon. LIG can be written into target materials in patterns and used as a supercapacitor, an electrocatalyst for fuel cells, radio-frequency identification (RFID) antennas and biological sensors, among other potential applications.

The new work reported in the American Chemical Society journal ACS Nano demonstrated that laser-induced graphene can be burned into paper, cardboard, cloth, coal and certain foods, even toast.

“Very often, we don’t see the advantage of something until we make it available,” Tour said. “Perhaps all food will have a tiny RFID tag that gives you information about where it’s been, how long it’s been stored, its country and city of origin and the path it took to get to your table.”

He said LIG tags could also be sensors that detect E. coli or other microorganisms on food. “They could light up and give you a signal that you don’t want to eat this,” Tour said. “All that could be placed not on a separate tag on the food, but on the food itself.”

Multiple laser passes with a defocused beam allowed the researchers to write LIG patterns into cloth, paper, potatoes, coconut shells and cork, as well as toast. (The bread is toasted first to “carbonize” the surface.) The process happens in air at ambient temperatures.


“In some cases, multiple lasing creates a two-step reaction,” Tour said. “First, the laser photothermally converts the target surface into amorphous carbon. Then on subsequent passes of the laser, the selective absorption of infrared light turns the amorphous carbon into LIG. We discovered that the wavelength clearly matters.”

The researchers turned to multiple lasing and defocusing when they discovered that simply turning up the laser’s power didn’t make better graphene on a coconut or other organic materials. But adjusting the process allowed them to make a micro supercapacitor in the shape of a Rice “R” on their twice-lased coconut skin.

Defocusing the laser sped the process for many materials as the wider beam allowed each spot on a target to be lased many times in a single raster scan. That also allowed for fine control over the product, Tour said. Defocusing allowed them to turn previously unsuitable polyetherimide into LIG.

“We also found we could take bread or paper or cloth and add fire retardant to them to promote the formation of amorphous carbon,” said Rice graduate student Yieu Chyan, co-lead author of the paper. “Now we’re able to take all these materials and convert them directly in air without requiring a controlled atmosphere box or more complicated methods.”

The common element of all the targeted materials appears to be lignin, Tour said. An earlier study relied on lignin, a complex organic polymer that forms rigid cell walls, as a carbon precursor to burn LIG in oven-dried wood. Cork, coconut shells and potato skins have even higher lignin content, which made it easier to convert them to graphene.

Tour said flexible, wearable electronics may be an early market for the technique. “This has applications to put conductive traces on clothing, whether you want to heat the clothing or add a sensor or conductive pattern,” he said.


Rice alumnus Ruquan Ye is co-lead author of the study. Co-authors are Rice graduate student Yilun Li and postdoctoral fellow Swatantra Pratap Singh and Professor Christopher Arnusch of Ben-Gurion University of the Negev, Israel. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of computer science and of materials science and nanoengineering at Rice.

The Air Force Office of Scientific Research supported the research.

Rice University: NEWT: New One-Step Catalyst Converts Nitrates to Water and Air

Rice Water Air Nitrates 159751_webRice University’s indium-palladium nanoparticle catalysts clean nitrates from drinking water by converting the toxic molecules into air and water. Credit Jeff Fitlow/Rice University

A simple, one-step catalyst could help yield cleaner drinking water with less nitrates.

A team from Rice University’s Nanotechnology Enabled Water Treatment (NEWT) Center have discovered that a catalyst made from indium and palladium can clean toxic nitrates from drinking water by converting them into air and water.

“Indium likes to be oxidized,” co-author Kim Heck, a research scientist at Rice, said in a statement. “From our in situ studies, we found that exposing the catalysts to solutions containing nitrate caused the indium to become oxidized.

“But when we added hydrogen-saturated water, the palladium prompted some of that oxygen to bond with the hydrogen and form water, and that resulted in the indium remaining in a reduced state where it’s free to break apart more nitrates,” she added.

In previous research, the researchers discovered that gold-palladium nanoparticles were not good catalysts for breaking apart nitrates. This led to the discovery of indium and palladium as a suitable catalyst.

“Nitrates are molecules that have one nitrogen atom and three oxygen atoms,” Rice chemical engineer Michael Wong, the lead scientist on the study, said in a statement. “Nitrates turn into nitrites if they lose an oxygen, but nitrites are even more toxic than nitrates, so you don’t want to stop with nitrites. Moreover, nitrates are the more prevalent problem.

“Ultimately, the best way to remove nitrates is a catalytic process that breaks them completely apart into nitrogen and oxygen or in our case, nitrogen and water because we add a little hydrogen,” he added. “More than 75 percent of Earth’s atmosphere is gaseous nitrogen, so we’re really turning nitrates into air and water.”

Nitrates, which could also be a carcinogenic, are considered toxic to both infants and pregnant women.

Nitrate pollution is common in agricultural communities, especially in the U.S. Corn Belt and California’s Central Valley, where fertilizers are heavily used. Studies have shown that nitrate pollution is on the rise because of changing land-use patterns. 1-california-drought-farms

The Environmental Protection Agency regulates allowable limits both nitrates and nitrites for safe drinking water. In communities with polluted wells and lakes, that typically means pretreating drinking water with ion-exchange resins that trap and remove nitrates and nitrites without destroying them.

“Nitrates come mainly from agricultural runoff, which affects farming communities all over the world,” Wong said. “Nitrates are both an environmental problem and health problem because they’re toxic.

“There are ion-exchange filters that can remove them from water, but these need to be flushed every few months to reuse them, and when that happens, the flushed water just returns a concentrated dose of nitrates right back into the water supply.”

The researchers will now try to develop a commercially viable water-treatment system.

“That’s where NEWT comes in,” Wong said. “NEWT is all about taking basic science discoveries and getting them deployed in real-world conditions.

“This is going to be an example within NEWT where we have the chemistry figured out, and the next step is to create a flow system to show proof of concept that the technology can be used in the field,” he added.

The study was published in ACS Catalysis.

Rice University Study Boosts Hope for Cheaper Fuel Cells


Rice researchers show how to optimize nanomaterials for fuel-cell cathodes

Nitrogen-doped carbon nanotubes or modified graphene nanoribbons may be suitable replacements for platinum for fast oxygen reduction, the key reaction in fuel cells that transform chemical energy into electricity, according to Rice University researchers.

The findings are from computer simulations by Rice scientists who set out to see how carbon nanomaterials can be improved for fuel-cell cathodes. Their study reveals the atom-level mechanisms by which doped nanomaterials catalyze oxygen reduction reactions (ORR).

The research appears in the Royal Society of Chemistry journal Nanoscale.

Theoretical physicist Boris Yakobson and his Rice colleagues are among many looking for a way to speed up ORR for fuel cells, which were discovered in the 19th century but not widely used until the latter part of the 20th. They have since powered transportation modes ranging from cars and buses to spacecraft.

The Rice researchers, including lead author and former postdoctoral associate Xiaolong Zou and graduate student Luqing Wang, used computer simulations to discover why graphene nanoribbons and carbon nanotubes modified with nitrogen and/or boron, long studied as a substitute for expensive platinum, are so sluggish and how they can be improved.

Doping, or chemically modifying, conductive nanotubes or nanoribbons changes their chemical bonding characteristics. They can then be used as cathodes in proton-exchange membrane fuel cells. In a simple fuel cell, anodes draw in hydrogen fuel and separate it into protons and electrons. While the negative electrons flow out as usable current, the positive protons are drawn to the cathode, where they recombine with returning electrons and oxygen to produce water.

The models showed that thinner carbon nanotubes with a relatively high concentration of nitrogen would perform best, as oxygen atoms readily bond to the carbon atom nearest the nitrogen. Nanotubes have an advantage over nanoribbons because of their curvature, which distorts chemical bonds around their circumference and leads to easier binding, the researchers found.

Rice logo_rice3The tricky bit is making a catalyst that is neither too strong nor too weak as it bonds with oxygen. The curve of the nanotube provides a way to tune the nanotubes’ binding energy, according to the researchers, who determined that “ultrathin” nanotubes with a radius between 7 and 10 angstroms would be ideal. (An angstrom is one ten-billionth of a meter; for comparison, a typical atom is about 1 angstrom in diameter.)

They also showed co-doping graphene nanoribbons with nitrogen and boron enhances the oxygen-absorbing abilities of ribbons with zigzag edges. In this case, oxygen finds a double-bonding opportunity. First, they attach directly to positively charged boron-doped sites. Second, they’re drawn by carbon atoms with high spin charge, which interacts with the oxygen atoms’ spin-polarized electron orbitals. While the spin effect enhances adsorption, the binding energy remains weak, also achieving a balance that allows for good catalytic performance.

The researchers showed the same catalytic principles held true, but to lesser effect, for nanoribbons with armchair edges.

“While doped nanotubes show good promise, the best performance can probably be achieved at the nanoribbon zigzag edges where nitrogen substitution can expose the so-called pyridinic nitrogen, which has known catalytic activity,” Yakobson said.

“If arranged in a foam-like configuration, such material can approach the efficiency of platinum,” Wang said. “If price is a consideration, it would certainly be competitive.”

Zou is now an assistant professor at Tsinghua-Berkeley Shenzhen Institute in Shenzhen City, China. Yakobson is the Karl F. Hasselmann Professor of Materials Science and NanoEngineering and a professor of chemistry.

The research was supported by the Robert Welch Foundation, the Army Research Office, the Development and Reform Commission of Shenzhen Municipality, the Youth 1000-Talent Program of China and Tsinghua-Berkeley Shenzhen Institute.