University of Illinois at Chicago researchers report new research showing that a number of 2D materials, when incorporated into experimental lithium-air batteries as the catalyst, enabled a battery to hold up to 10 times more energy than lithium-air batteries containing traditional catalysts.

Lithium-air batteries are poised to become the next revolutionary replacement for currently used lithium-ion batteries that power electric vehicles, cell phones and computers.

2D catalysts power an electric vehicle. Image Credit: Amin Salehi-Khojin, University of Illinois at Chicago. Click image for the largest view.

Lithium-air batteries, which currently are still in the experimental stages of development, can store 10 times more energy than lithium-ion batteries, and they are much lighter. That said, lithium-air batteries could be even more efficient and provide more charge with the incorporation of advanced catalysts made from two-dimensional materials. Catalysts help increase the rate of chemical reactions inside batteries, and depending on the type of material from which the catalyst is made, they can help significantly boost the ability of the battery to hold and provide energy.

Amin Salehi-Khojin, associate professor of mechanical and industrial engineering in UIC’s College of Engineering said, “We are going to need very high-energy density batteries to power new advanced technologies that are incorporated into phones, laptops and especially electric vehicles.”

Salehi-Khojin and his colleagues synthesized several 2D materials that can serve as catalysts. A number of their 2D materials, when incorporated into experimental lithium-air batteries as the catalyst, enabled the battery to hold up to 10 times more energy than lithium-air batteries containing traditional catalysts. Their findings have been published in the journal Advanced Materials.

“Currently, electric vehicles average about 100 miles per charge, but with the incorporation of 2D catalysts into lithium-air batteries, we could provide closer to 400 to 500 miles per charge, which would be a real game-changer,” said Salehi-Khojin, who is also the corresponding author of the paper. “This would be a huge breakthrough in energy storage.”

Salehi-Khojin and his colleagues synthesized 15 different types of 2D transition metal dichalcogenides or TMDCs. TMDCs are unique compounds because they have high electronic conductivity and fast electron transfer that can be used to participate in reactions with other materials, such as the reactions that take place inside batteries during charging and discharging.

The investigators experimentally studied the performance of 15 TMDCs as catalysts in an electrochemical system mimicking a lithium-air battery.

“In their 2D form, these TMDCs have much better electronic properties and greater reactive surface area to participate in electrochemical reactions within a battery while their structure remains stable,” explained Leily Majidi, a graduate student in the UIC College of Engineering and first author of the paper. “Reaction rates are much higher with these materials compared to conventional catalysts used such as gold or platinum.”

One of the reasons the 2D TDMCs performed so well is because they help speed both charging and discharging reactions occurring in lithium-air batteries. “This would be what is known as bi-functionality of the catalyst,” explained Salehi-Khojin.

The 2D materials also synergize with the electrolyte – the material through which ions move during charge and discharge.

“The 2D TDMCs and the ionic liquid electrolyte that we used acts as a co-catalyst system that helps the electrons transfer faster, leading to faster charges and more efficient storage and discharge of energy. These new materials represent a new avenue that can take batteries to the next level, we just need to develop ways to produce and tune them more efficiently and in larger scales,” Salehi-Khojin said.

This report strongly suggests that this technology could be quite close to going for scaling up. Thus, a listing of the team members: Poya Yasaei, Zahra Hemmat, Pedram Abbasi, Shadi Fuladi, Xuan Hu, Robert Klie, Fatemeh Khalili-Araghi and Baharak Sayahpour of the University of Illinois at Chicago and Robert Warburton and Jeffrey Greeley of Purdue University are coauthors on the paper.

The battle seems joined – lithium air and lithium metal plus other chemistries.

Go folks! World economic progress needs your success.

Korea’s Daegu Gyeongbuk Institute of Science and Technology (DGIST) researchers have fabricated nano-sized catalysts that could improve the performance and production of clean energy fuel cells.

Professor Sangaraju Shanmugam (left) and Ph.D Student Arumugam Sivanantham (right). Image Credit:Daegu Gyeongbuk Institute of Science and Technology. Click image for the largest view.

The team’s study results have been published in the journal of Applied Catalysis B: Environmental.

Polymer electrolyte membrane fuel cells (PEMFCs) transform the chemical energy produced during a reaction between hydrogen fuel and oxygen into electrical energy. While PEMFCs are a promising source of clean energy that is self-contained and mobile – much like the alkaline fuel cells used on the US Space Shuttle – they currently rely on expensive materials. Also, the substances used for catalyzing these chemical reactions degrade, raising concerns about reusability and viability.

DGIST energy materials scientist Sangaraju Shanmugam and his team have developed active and durable catalysts for PEMFCs that can reduce the overall manufacturing costs. The catalysts were nitrogen-doped carbon nanorods with ceria and cobalt nanoparticles on their surfaces; essentially carbon nanorods containing nitrogen, cobalt and ceria. Ceria (CeO2), a combination of cerium and oxygen, is a cheap and environmentally friendly semiconducting material that has excellent oxygen reduction abilities.

The fibers were made using a technique known as electrospinning, in which a high voltage is applied to a liquid droplet, forming a charged liquid jet that then dries midflight into uniform, nanosized particles. The researchers’ analyses confirmed that the ceria and cobalt particles were uniformly distributed in the carbon nanorods and that the catalysts showed enhanced electricity-producing capacity.

The ceria-supported cobalt on nitrogen-doped carbon nanorod catalyst was found to be more active and durable than cobalt-only nitrogen-doped carbon nanorods and platinum/carbon. They were explored in two important types of chemical reactions for energy conversion and storage: oxygen reduction and oxygen evolution reactions.

The researchers concluded that ceria could be considered among the most promising materials for use with cobalt on nitrogen-doped carbon nanorods to produce stable catalysts with enhanced electrochemical activity in PEMFCs and related devices.

Its more good news for the fuel cell field. Things are coming strongly enough and with enough improvement that an engineer has to wonder if a design is obsolete before it can be prototyped. This may only be a lab sample, but the potential demands a larger sized sample look.

Princeton Plasma Physics Laboratory (PPPL) researchers are describing a newly discovered stabilizing effect of an underappreciated 1983 finding that variations in plasma temperature can influence the growth of magnetic islands that lead to disruption of fusion plasmas.  The discovery could help scientists seeking to bring the fusion reaction that powers the sun and stars to Earth that must keep the superhot plasma free from disruptions.

Replicating fusion, which releases boundless energy by fusing atomic nuclei in the state of matter known as plasma, could produce clean and virtually limitless power for generating electricity for cities and industries everywhere.  Capturing and controlling fusion energy is therefore a key scientific and engineering challenge for researchers across the globe.

The PPPL finding, reported in Physical Review Letters, focuses on so-called tearing modes – instabilities in the plasma that create magnetic islands, a key source of plasma disruptions.  These islands, bubble-like structures that form in the plasma, can grow and trigger disruptive events that halt fusion reactions and damage doughnut-shaped facilities called “tokamaks” that house the reactions.

Researchers found in the 1980s that using radio-frequency (RF) waves to drive current in the plasma could stabilize tearing modes and reduce the risk of disruptions. However, the researchers failed to notice that small changes – or perturbations – in the temperature of the plasma could improve the stabilization process, once a key threshold in power is exceeded. The physical mechanism that PPPL has identified works like this:

  • The temperature perturbations affect the strength of the current drive and the amount of RF power deposited in the islands.
  • The perturbations and their impact on the deposition of power feedback against each other in a complex – or nonlinear – manner.
  • When the feedback combines with the sensitivity of the current drive to temperature perturbations, the efficiency of the stabilization process increases.
  • Furthermore, the improved stabilization is less to likely to be affected by misaligned current drives that fail to hit the center of the island.

The overall impact of this process creates what is technically called “RF current condensation,” or concentration of RF power inside the island that keeps it from growing.

“The power deposition is greatly increased,” said Allan Reiman, a theoretical physicist at PPPL and lead author of the paper. “When the power deposition in the island exceeds a threshold level, there is a jump in the temperature that greatly strengthens the stabilizing effect. This allows the stabilization of larger islands than previously thought possible.”

This process can be particularly beneficial to ITER, the international tokamak under construction in France to demonstrate the feasibility of fusion power. “There is worry about islands getting large and causing disruptions in ITER,” Reiman said. “Taken together, these new effects should make it easier to stabilize ITER plasmas.”

Reiman worked with Professor Nat Fisch, associate director for academic affairs at PPPL and coauthor of the report. Fisch had demonstrated in a landmark 1970s paper that RF waves could be used to drive currents to confine tokamak plasmas through a process now called “RF current drive.”

Fisch points out how “it was Reiman’s groundbreaking paper in 1983 that predicted that these RF currents could also stabilize tearing modes. The use of RF current drive for stabilization of tearing modes was perhaps even more crucial to the tokamak program than using these currents to confine the plasma.”

“Hence,” he said, “Reiman’s 1983 paper essentially launched experimental campaigns on tokamaks worldwide to stabilize tearing modes.” Moreover, he added, “Significantly, in addition to predicting the stabilization of tearing modes by RF, the 1983 paper also pointed out the importance of the temperature perturbation in magnetic islands.”

The new paper takes a fresh look at the impact of these temperature perturbations on the islands, a feature which has been underappreciated since the 1983 paper pointed to it.  “We basically went back 35 years to carry that thought just a bit further by exploring the fascinating physics and larger implications of positive feedback,” Fisch said. “It turned out that these implications might now be very important to the tokamak program today.”

The theoreticians began their recent work with a simple model and advanced to more complex ones to address the key issues. They now plan to produce a more detailed picture with still-more sophisticated models. They are also working to suggest experimental campaigns that will expose these new effects. Support for this research comes from the DOE Office of Science.

This is one more step of an unknown number needed to get the legs under tokamak fusion devices.  There remains a very long way to go and billions of more dollars to spend trying to control the interior of a donut.

Politecnico di Torino engineers have developed an innovative, low-cost technology to turn seawater into drinking water using solar energy alone.

According to FAO estimates, by 2025 nearly 2 billion people may not have enough drinking water to satisfy their daily needs. One of the possible solutions to this problem is desalination, treating seawater to make it drinkable. However, removing salt from seawater requires 10 to 1000 times more energy than traditional methods of freshwater supply, such as pumping water from rivers or wells.

Solar distiller during the tests carried out in the Ligurian Sea. Image Credit: Politecnico di Torino. Click image for the largest view.

Motivated by this problem, a team of engineers from the Department of Energy of Politecnico di Torino has devised a new prototype to desalinate seawater in a sustainable and low-cost way, using solar energy more efficiently. Compared to previous solutions, the developed technology is in fact able to double the amount of water produced at given solar energy, and it may be subject to further efficiency improvement in the near future.

The group of young researchers who recently published these results in the journal Nature Sustainability is composed of Eliodoro Chiavazzo, Matteo Morciano, Francesca Viglino, Matteo Fasano and Pietro Asinari (Multi-Scale Modeling Lab).

The working principle of the proposed technology is very simple. Matteo Fasano and Matteo Morciano explain, “Inspired by plants, which transport water from roots to leaves by capillarity and transpiration, our floating device is able to collect seawater using a low-cost porous material, thus avoiding the use of expensive and cumbersome pumps. The collected seawater is then heated up by solar energy, which sustains the separation of salt from the evaporating water. This process can be facilitated by membranes inserted between contaminated and drinking water to avoid their mixing, similarly to some plants able to survive in marine environments (for example the mangroves).”

While conventional ‘active’ desalination technologies need costly mechanical or electrical components (such as pumps and/or control systems) and require specialized technicians for installation and maintenance, the desalination approach proposed by the team at Politecnico di Torino is based on spontaneous processes occurring without the aid of ancillary machinery and can, therefore, be referred to as ‘passive’ technology.

These points make the device inherently inexpensive and simple to install and repair. The latter features are particularly attractive in coastal regions that are suffering from a chronic shortage of drinking water and are not yet reached by centralized infrastructures and investments.

Currently a well-known disadvantage of ‘passive’ technologies for desalination has been the low energy efficiency as compared to ‘active’ ones. The researchers at Politecnico di Torino have faced this obstacle with creatively, “While previous studies focused on how to maximize the solar energy absorption, we have shifted the attention to a more efficient management of the absorbed solar thermal energy. In this way, we have been able to reach record values of productivity up to 20 liters per day of drinking water per square meter exposed to the Sun. The reason behind the performance increase is the ‘recycling’ of solar heat in several cascade evaporation processes, in line with the philosophy of ‘doing more, with less’. Technologies based on this process are typically called ‘multi-effect’, and here we provide the first evidence that this strategy can be very effective for ‘passive’ desalination technologies as well.”

After developing the prototype for more than two years and testing it directly in the Ligurian sea (Varazze, Italy), the Politecnico engineers claim that this technology could have an impact in isolated coastal locations with little drinking water but abundant solar energy, especially in developing countries.

Additionally the technology is particularly suitable for providing safe and low-cost drinking water in emergency conditions, for example in areas hit by floods or tsunamis and left isolated for days or weeks from the electricity grid or aqueduct supplies.

A further application envisioned for this technology are floating gardens for food production, an interesting option especially in overpopulated areas.

The researchers, who continue to work on this issue within the Clean Water Center at Politecnico di Torino, are now looking for possible industrial partners to make the prototype more durable, scalable and versatile. For example, engineered versions of the device could be employed in coastal areas where over-exploitation of groundwater causes the intrusion of saline water into freshwater aquifers (a particularly serious problem in some areas of Southern Italy), or could treat waters polluted by industrial or mining plants.

The prospect of large desalination projects using vast amounts of electrical power has put many proposed projects into conservation efforts and even postponement. Osmosis is available, but still uses a great deal of power and are quite expensive to operate and maintain. These hard realities are going to make this team’s efforts and results very welcome indeed -across a much larger market than may be supposed today.

Kanazawa University scientists have developed a method to sort molecules of carbon monoxide from carbon dioxide. This development may prove very helpful in recycling CO2 and expanding the field of producing alternative fuels.

Anion structures of CH2Cl2(guest)-inserted V12 (left) and guest-free V12 are shown. Orange and red square pyramids represent VO5 units with their bases directed to the center of the bowl, and the inverted VO5 unit. Green and black spheres represent Cl and C, respectively. Hydrogen atoms of CH2Cl2 are omitted for clarity. Image Credit: Kanazawa University. Click image for the largest view.

So, how do you separate carbon dioxide from carbon monoxide? One way, showcased in a new study from the Kanazawa scientists published in the Angewandte Chemie International Edition journal, is to use a bowl of vanadium. More precisely, a hollow, spherical cluster of vanadate molecules can discriminate between CO and CO2, allowing potential uses in CO2 storage and capture.

The Kanazawa scientists studied host-guest interactions in vanadate clusters. V12 is a spherical bowl that hosts small molecules in its interior. The team created empty (guest-free) V12 for the first time. One of the 12 units of VO5 was found to flip inwards to fill the void vacated by the guest. Empty V12 could absorb CO2 but rejected CO, offering a way to separate these molecules for CO2 capture.

At the molecular scale, small objects can fit inside larger ones, just like in the everyday world. The resulting arrangements, known as host-guest interactions, are stabilized by non-covalent forces like electrostatics and hydrogen bonds. Each host will happily take in certain molecules, while shutting out others, depending on the size of its entrance and how much interior space it can offer the guest.

One such host is V12 – a rough sphere made from 12 atoms of the transition metal vanadium, connected through 32 oxygen atoms. The bowl-like structure has an opening at one end, with a width of 0.44 nanometers, perfect for letting in the right molecule to nestle inside the cavity.

Yuji Kikukawa, co-corresponding author of the study said, “V12 accepts a range of guests on the scale of small organic compounds. In fact, it’s rather hard to isolate an empty V12 by itself. While the host stabilizes its guest, so the guest returns the favor – if we remove the guest, the host quickly replaces it with another molecule.”

Each vanadium atom in V12 forms a square-pyramid with five oxygens. The oxygens of each VO5 point outwards, while the positive charge from vanadium fills the inner cavity, helping to stabilize electron-rich (or anionic) guests. However, the Kanazawa team created a guest-free V12 for the first time, by using a solvent – acetone – whose molecules are too bulky to fit through the entrance.

To make up for the missing guest, the empty V12 bowl did something unexpected. The VO5 unit at the bottom flipped inwards, like an umbrella inverting in heavy wind. Now, the host cavity was filled by the negative terminal oxygen of the single “upside-down” VO5. This atomic shifting to accommodate a new structure, termed a polytopal rearrangement, had never been seen in metal oxide clusters. The structure transformation could be monitored by infrared spectroscopy.

The study authors explained, “We then took the empty V12 and explored which guests we could insert back into the bowl. Nitrogen, methane and carbon monoxide were all rejected, but carbon dioxide was readily taken up. This immediately suggests a way to separate CO2 from other gases.”

In fact, V12 and CO2 proved such a perfect fit that CO2 could be inserted even at low atmospheric pressure. V12 might therefore be an ideal solution in CO2 capture to combat climate change, and even in CO2 storage for the emerging technology of artificial photosynthesis.

This looks like a potential breakthrough. Admittedly there is quite a long way to go to see something that could scale up to useful dimensions. Yet the incentive is great, getting CO2 freed from gas compounds could make many processes work much better as well as set up more ways to use CO2.


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