GT/ Breakthrough in converting CO2 into fuel using solar energy
Energy & green technology biweekly vol.18, 15th February — 28th February
TL;DR
- A research team has shown how solar power can convert carbon dioxide (CO2) into fuel, by using advanced materials and ultra-fast laser spectroscopy. The breakthrough could be an important piece of the puzzle in reducing the levels of greenhouse gases in the atmosphere in the future.
- Researchers have shown that solar cells can be used to achieve underwater wireless optical communication with high data rates. The new approach — which used an array of series-connected solar cells as detectors — could offer a cost-effective, low-energy way to transmit data underwater.
- Researchers have developed a new and simple method for upcycling plastic waste at room temperature.
- A chemical used in electric vehicle batteries could also give us carbon-free fuel for space flight, according to new research.
- Researchers have developed a patented hybrid device — part living organism, part bio battery, capable of producing stored energy by increasing energy flow under light conditions where natural photosynthesis is normally inhibited.
- Researchers have found a new method to induce the piezoelectric effect in materials that are otherwise not piezoelectric. It can pave the way for new uses and more environmentally friendly materials.
- Researchers engineered a strain of bacteria to break down CO2, converting it into commonly used, expensive industrial chemicals. The carbon-negative approach removes CO2 from the atmosphere and bypasses using fossil fuels to generate these chemicals.
- Researchers have developed a new type of catalyst material, called a metal hydroxide-organic framework (MHOF), which is made of inexpensive and abundant components. The catalyst speeds up the electrochemical reaction that splits apart water molecules to produce oxygen, which is at the heart of multiple approaches aiming to produce alternative fuels for transportation.
- Recycling of electric car batteries can be easier, cheaper, and more environmentally friendly, according to a new scientific article, which outlines an optimized recycling process. The research represents a vital step towards the electromobility society of the future.
- From foraging for prey to evading predators and ship strikes, a dolphin’s survival depends on speedy swimming, but burning all that energy can delete the metabolic reserves vital for growth, health and reproduction. A new study provides scientists with a new metric for estimating how much energy wild dolphins expend on swimming — information that is essential for answering fundamental questions about their physiology and ecology, and for understanding the impacts of human disturbances on them.
- And more!
Green Technology Market
Green technology is an applicable combination of advanced tools and solutions to conserve natural resources and environment, minimize or mitigate negative impacts from human activities on the environment, and ensure sustainability development. Green technology is also referred to as clean technology or environmental technology which includes technologies, such as IoT, AI, analytics, blockchain, digital twin, security, and cloud, which collect, integrate, and analyze data from various real-time data sources, such as sensors, cameras, and Global Positioning System (GPS).
Green technology, also known as sustainable technology, protects the environment by using various forms of sustainable energy. Some of the best examples of green technologies include solar panels, LED lighting, wind energy, electric vehicles, vertical farming, and composting.
The global Green Technology and Sustainability market size to grow from USD 11.2 billion in 2020 to USD 36.6 billion by 2025, at a Compound Annual Growth Rate (CAGR) of 26.6% during the forecast period. The growing consumer and industrial interest for the use of clean energy resources to conserve environment and increasing use of Radio Frequency Identification sensors across industries are driving the adoption of green technology and sustainability solutions and services in the market.
The blockchain segment is estimated to grow at the highest CAGR: Energy-intensive cryptocurrency mining has caused a spike in carbon emission, and hence blockchain is capable of driving innovation in the field of green technology.
Latest Research
Ultrafast charge transfer dynamics in 2D covalent organic frameworks/Re-complex hybrid photocatalyst
by Qinying Pan, Mohamed Abdellah, Yuehan Cao, Weihua Lin, Yang Liu, Jie Meng, Quan Zhou, Qian Zhao, Xiaomei Yan, Zonglong Li, Hao Cui, Huili Cao, Wenting Fang, David Ackland Tanner, Mahmoud Abdel-Hafiez, Ying Zhou, Tonu Pullerits, Sophie E. Canton, Hong Xu, Kaibo Zheng in Nature Communications
A research team led by Lund University in Sweden has shown how solar power can convert carbon dioxide into fuel, by using advanced materials and ultra-fast laser spectroscopy. The breakthrough could be an important piece of the puzzle in reducing the levels of greenhouse gases in the atmosphere in the future.
The sunlight that hits Earth during one hour corresponds roughly to humanity’s total energy consumption for an entire year. Our global carbon dioxide emissions are also increasing. Using the sun’s energy to capture greenhouse gases and converting it into fuel or another useful chemical, is a research focus for many today. However, there is still no satisfactory solution, but an international research team has now revealed a possible way forward.
“The study uses a combination of materials that absorb sunlight and use its energy to convert carbon dioxide. With the help of ultra-fast laser spectroscopy, we have mapped exactly what happens in that process,” says Tönu Pullerits, chemistry researcher at Lund University.
The researchers have studied a porous organic material called COF — covalent organic framework. The material is known for absorbing sunlight very efficiently. By adding a so-called catalytic complex to COF, they succeeded, without any additional energy, in converting carbon dioxide to carbon monoxide.
“The conversion to carbon monoxide requires two electrons. When we discovered that photons with blue light create long-lived electrons with high energy levels, we could simply charge COF with electrons and complete a reaction,” says Kaibo Zheng, chemistry researcher at Lund University.
How can these results be useful? Tönu Pullerits and Kaibo Zheng hope that in the future the discovery can be used to develop larger units that can be used on a global level to, with the help of the sun, absorb carbon dioxide from the atmosphere and convert it into fuel or chemicals. That could be one of many solutions to overcome the climate crisis we are facing.
“We have completed two initial steps with two electrons. Before we can start thinking about a carbon dioxide converter, many more steps need to be taken, and probably even our first two must be refined. But we have identified a very promising direction to take,” concludes Tönu Pullerits.
Series-connected solar array for high-speed underwater wireless optical links
by Zhijian Tong, Xingqi Yang, Hao Zhang, Yizhan Dai, Xiao Chen, Jing Xu inOptics Letters
Although solar cells are typically designed to turn light into power, researchers have shown that they can also be used to achieve underwater wireless optical communication with high data rates. The new approach — which used an array of series-connected solar cells as detectors — could offer a cost-effective, low-energy way to transmit data underwater.
“There is a critical need for efficient underwater communication to meet the increasing demands of underwater data exchange in worldwide ocean protection activities,” said research team leader Jing Xu from Zhejiang University in China. For example, in coral reef conservation efforts, data links are necessary to transmit data from divers, manned submarines, underwater sensors and unmanned autonomous underwater vehicles to surface ships supporting their work.
Xu and colleagues report on laboratory experiments in which they used an array of commercially available solar cells to create an optimized lens-free system for high-speed optical detection underwater. Solar cells offer a much larger detection area than the photodiodes traditionally used as detectors in wireless optical communication.
“To the best of our knowledge, we demonstrated the highest bandwidth ever achieved for a commercial silicon solar panel-based optical communication system with a large detection area,” said Xu. “This type of system could even allow data exchange and power generation with one device.”
Compared to using radio or acoustic waves, light-based underwater wireless communication exhibits higher speed, lower latency and requires less power. However, most long-distance high-speed optical systems are not practical for underwater implementation because they require strict alignment between the transmitter emitting the light and the receiver that detects the incoming light signal. Because solar eclls detect light from a large area and convert it to an electrical signal, using them as detectors can ease the transmitter-receiver alignment requirement in an underwater wireless communication system. However, it has been difficult to achieve high bandwidth because solar cells are optimized for energy harvesting rather than communication.
“Until now, achieving high-speed links using off-the-shelf silicon solar cells has required complex modulation schemes and algorithms, which need intense computing resources that use extra power and create a high processing latency,” said Xu. “Using modeling and simulation of connected solar cells, we optimized the peripheral circuit, which significantly improved the performance of our solar cell-based detector.”
The researchers tested the new design, which used a 3×3 solar array to create a detection area of 3.4 × 3.4 centimeters, in a 7-meter-long water tank that emulated an underwater channel. Mirrors were used to extend the pathlength of the optical signal, creating a transmission distance of 35 meters. The system showed reliable stability, low power consumption and high performance. As the size of the solar array increases from 1×1 to 3×3, the ?20-dB bandwidth increases from 4.4 MHz to 24.2 MHz.
Even though a simple modulation scheme was used, the new system exhibited a much higher detection bandwidth — which leads to a higher data rate — than has been reported in other studies using commercial silicon solar cells with a large detection area as detectors. Applying a reverse bias voltage of 90 V boosted the bandwidth further, allowing them to achieve a ?20-dB bandwidth of 63.4 MHz. This bandwidth enabled a 35-m/150-Mbps underwater wireless optical link using the simplest form of amplitude-shift keying modulation.
“Because solar cells are mass produced, the proposed scheme is quite cost effective,” said Xu. “Beyond the underwater world, this type of detector could also be used in visible light communication, a type of wireless communication that uses visible light from LEDs and other sources to transmit data across distances.”
To optimize the system for real-world applications in underwater communication, the researchers plan to next study its performance with weak optical signals. This will show how well it works in muddy water and with movement. They are also working to make the system more practical by fine tuning key parameters like the number of solar cells in the array and the required reverse bias voltage.
Rerouting Pathways of Solid-State Ammonia Borane Energy Release
by Prithwish Biswas, Pankaj Ghildiyal, Hyuna Kwon, Haiyang Wang, Zaira Alibay, Feiyu Xu, Yujie Wang, Bryan M. Wong, Michael R. Zachariah in The Journal of Physical Chemistry
A chemical used in electric vehicle batteries could also give us carbon-free fuel for space flight, according to new UC Riverside research. In addition to emission reductions, this chemical also has several advantages over other types of rocket fuels: higher energy, lower costs, and no requirement for frozen storage.
The chemical, ammonia borane, is currently used for storing the hydrogen in fuel cells that power electric vehicles. UCR researchers now understand how this combination of boron and hydrogen can release enough energy to also launch rockets and satellites.
“We are the first to demonstrate that in addition to electric vehicles, ammonia borane can be used to make rockets go too, under the right conditions,” said Prithwish Biswas, UCR chemical engineer and first author of the new study.
The most commonly used rocket fuels are hydrocarbon based and are known to have a variety of negative environmental impacts. They can poison the soil for decades, cause cancer, and produce acid rains, ozone holes and greenhouse gases like carbon dioxide. By contrast, once burned, ammonia borane releases the benign compounds boron oxide and water. “It is much less harmful to the environment,” said Biswas.
Compared with hydrocarbon fuels, ammonia borane also releases more energy, potentially resulting in cost savings because less of it is required to power the same flight. To release energy from the fuel and enable combustion, catalysts and oxidizers are added to supply extra oxygen to the fuel. Fuel cells often employ catalysts for this purpose. They enhance the rate of combustion, but they also stay in the same form both before and after the reaction.
“Spacecraft require high amounts of energy in a short amount of time, so it’s not ideal to use a catalyst because it doesn’t contribute to the energy you need. It’s like dead mass in your gas tank,” said Pankaj Ghildiyal, University of Maryland chemistry Ph.D. student and study co-author, currently working at UCR.
The inherent chemistry of ammonia borane decomposition hinders the release of its total energy on reaction with most oxidizers. However, the researchers found an oxidizer that alters the decomposition and oxidation mechanisms of this fuel, leading to the extraction of its total energy content.
“This is analogous to the use of catalytic converters to enable the complete combustion of hydrocarbon fuels,” Ghildiyal said. “Here, we were able to create more complete combustion of the chemicals and increase the energy of the entire reaction by using the chemistry of the oxidizer itself, without needing a catalyst.”
In addition to creating undesirable byproducts, some rocket fuels also require storage at sub-freezing temperatures. “NASA has used liquid hydrogen, which has very low density,” Ghildiyal said. “It therefore requires a lot of space as well as cryogenic conditions for maintenance.”
By contrast, this fuel is stable at room temperature and is resistant to high heat. In this study, the researchers created very fine, nanoscale particles of ammonium borane, which could degrade over the course of a month in very humid environments.
The research team is now studying the way ammonium borane particles of various sizes age in different environments. They’re also developing methods of encapsulating particles of the fuel a protective coating, to enhance their stability in moist conditions.
“We’ve determined the fundamental chemistry that powers this fuel and oxidizer combination,” Biswas said. “Now we are looking forward to seeing how it performs at large scale.”
Versatile Chemical Recycling Strategies: Value‐Added Chemicals from Polyester and Polycarbonate Waste
by Jack M. Payne, Muhammad Kamran, Matthew G. Davidson, Matthew D. Jones in ChemSusChem
A new and simple method for upcycling plastic waste at room temperature has been developed by a team of researchers at the Centre for Sustainable and Circular Technologies (CSCT) at the University of Bath. The researchers hope the new process will help recycling become more economically viable.
Plastic waste residing in either landfill or the natural environment currently outweighs all living biomass (4 Giga tonnes), culminating in one of the great environmental challenges of the 21st century. Whilst recycling rates are increasing across Europe, traditional methods remain limited because the harsh remelting conditions reduce the quality of the material each time it’s recycled.
Now researchers at the CSCT have developed a mild and rapid chemical recycling process for polycarbonates, a robust class of plastics commonly used in construction and engineering. Using a zinc-based catalyst and methanol, they were able to completely break down commercial polybisphenol A carbonate (BPA-PC) beads within 20 minutes at room temperature.
The waste can then be converted into its chemical constituents, namely bisphenol A (BPA) and dimethyl carbonate (DMC), helping to preserve product quality over an infinite number of cycles. Importantly, BPA recovery prevents leakage of a potentially damaging environmental pollutant, whilst DMC is a valuable green solvent and building block for other industrial chemicals.
Promisingly, the catalyst is also tolerant to other commercial sources of BPA-PC (e.g. CD) and mixed waste feeds, increasing industrial relevance, whilst being amenable to other plastics (e.g. poly(lactic acid) (PLA) and poly(ethylene terephthalate) (PET)) at higher temperatures. The team has also demonstrated a completely circular approach to producing several renewable poly(ester-amide)s (PEAs) based on terephthalamide monomers derived from waste PET bottles. These materials have excellent thermal properties and could potentially be used in biomedical applications, for example drug delivery and tissue engineering.
Lead researcher Professor Matthew Jones, at the University of Bath’s CSCT, said: “It’s really exciting to see the versatility of our catalysts in producing a wide range of value-added products from plastic waste.
“It’s crucial we target such products, where possible, to help promote and accelerate the implementation of emerging sustainable technologies through economic incentives.”
First author of the paper, Jack Payne from the CSCT, said: “Whilst plastics will play a key role in achieving a low-carbon future, current practices are unsustainable.
“Moving forward, it’s imperative we source plastics from renewable feedstocks, embed biodegradability/recyclability at the design phase and diversify existing waste management strategies. “Such future innovation should not be limited to emerging materials but encompass established products too.
“Our method creates new opportunities for polycarbonate recycling under mild conditions, helping to promote a circular economy approach and keep carbon in the loop indefinitely.”
Electrochemically Driven Photosynthetic Electron Transport in Cyanobacteria Lacking Photosystem II
by Christine M. Lewis, Justin D. Flory, Thomas A. Moore, Ana L. Moore, Bruce E. Rittmann, Wim F.J. Vermaas, César I. Torres, Petra Fromme in Journal of the American Chemical Society
The quest for sustainable energy has become a central challenge for society. In order to meet ever-expanding energy demands without further damaging the global climate, researchers are tapping into natural processes that have provided plants and many animal forms with their energy source for billions of years. Their secret is the conversion of radiant light energy into chemical energy in the process of photosynthesis.
In new research, lead author Christine Lewis and her ASU colleagues describe a patented hybrid device — part living organism, part bio battery, capable of producing stored energy by increasing energy flow under light conditions where natural photosynthesis is normally inhibited.
The advancement of such technologies offers a green pathway to the production of a broad range of useful products, including transportation fuels, agrochemicals, therapeutics, cosmetics, plastics and specialty chemicals as well as human and animal supplements. The new study shows that modified photosynthetic microbes — in this case, cyanobacteria — can be fed electrons from an external source and use these to power chemical reactions that could eventually be harnessed for human applications. Researchers call this approach microbial electro photosynthesis or MEPS.
“This project involves unlocking the mysteries involved with energy transfer. Specifically, we work on bridging artificial energy with natural photosynthesis by tapping into the latter half of the photosynthetic electron transport chain,” Lewis says. “The research objectives are to have the ability to turn photosynthesis on at will, eventually to make it more efficient, and produce stable energy products.”
Lewis is a researcher in the Biodesign Center for Applied Structural Discovery (CASD), Swette Center for Environmental Biotechnology (EB), and ASU’s School of Molecular Sciences (SMS). She is joined by ASU colleagues Petra Fromme, director of the Center for Applied Structural Discovery; Bruce Rittmann, director of Swette Center for Environmental Biotechnology and professor from ASU’s School of Sustainable Engineering and the Built Environment; Wim Vermaas from ASU’s School of Life Sciences and Julie Ann Wrigley Global Institute of Sustainability (GIS); Cesar Torres from EB and ASU’s School for Engineering of Matter, Transport and Energy; Justin Flory, associate director for Engineering Center for Negative Carbon Emissions and Thomas and Anna Moore, from GIS, SMS and CASD.
The basic recipe for natural photosynthesis involves just a few key ingredients: water, sunlight, and CO2. Photosynthetic cells act as tiny factories for the production of glucose, which is then converted into ATP, the cell’s primary energy currency. In the process, oxygen is produced as a respiratory byproduct but can prove harmful to the photosynthetic process when damaging oxygen radical species are produced with high-intensity light.
Although photosynthesis is ideally suited to supplying the energy needs of plants and other photosynthetic organisms, the rate with which light is converted into useful chemical energy is far too low to be suitable to supply today’s human energy needs. Researchers have long sought out ways to tap into natural photosynthesis while also improving it to find carbon neutral energy solutions.
There are several important limiting factors in terms of energy conversion efficiency in natural photosynthesis. First, photosynthetic organisms use only a small portion of the spectrum of light emitted by the sun, namely red visible light. Second, the rate of carbon fixation is too slow for practical applications. Increasing it requires a boost in the rate of electrons moving through the transport chain. Finally, photosynthetic organisms can only deal with a limited quantity of sun-excited electrons at one time. If the electron transport chain is fed too many at once, the process can shut down due to light damage, disabling or killing the cell. This limitation on energy efficiency is primarily due to a key component in the cell’s electron transport machinery, a protein complex known as photosystem II (PS II).
In the new study, the MEPS system is described using a genetically modified cyanobacterium hitched to an external cathode. The cyanobacteria used were reengineered in the laboratory of co-author Wim Vermaas to carry out photosynthetic cycling of electrons without a photosystem II component. With the help of chemical mediators, electrons are shuttled from the device’s cathode into the electron transport chain of the cyanobacterium. Because the light-vulnerable photosystem II has been eliminated, the photosynthetic process takes place via an alternate pathway, namely through photosystem I.
The results verified that photosynthesis can indeed be carried out using an external supply of electrons feeding the electron transport chain, and it could be performed in the presence of extremely high-intensity light.
“One of my priorities as part of the team was finding the right electrochemical mediator to move electrons into the cell,” Torres said. “I think that one of the highlights was realizing we have alleviated some of the bigger limitations of Synechocystis (cyanobacteria) removing photosystem II for the system and giving them electrons from an electrode.”
The MEPS system could potentially use currently available solar cells to provide the external electrons needed to power photosynthetic reactions. Photovoltaics could supply electrons from wavelengths from zero all the way up to thousands of nanometers, providing a much broader spectrum for light harvesting than usually available to natural photosynthesis.
“By the year 2050, with global expansion moving at the pace that it is, our energy needs will surpass our supply. However, we can act now to learn how to provide efficient and cleaner energy,” Lewis says. “It is my goal to contribute to the next “breakthrough” that will help to make this big, blue marble a better place.”
Carbon-negative production of acetone and isopropanol by gas fermentation at industrial pilot scale
by Fungmin Eric Liew, Robert Nogle, Tanus Abdalla, et al in Nature Biotechnology
Researchers engineered a strain of bacteria to break down carbon dioxide (CO2), converting it into commonly used, expensive industrial chemicals. The carbon-negative approach removes CO2 from the atmosphere and bypasses using fossil fuels to generate these chemicals.
Bacteria are known for breaking down lactose to make yogurt and sugar to make beer. Now researchers led by Northwestern University and LanzaTech have harnessed bacteria to break down waste carbon dioxide (CO2) to make valuable industrial chemicals.
In a new pilot study, the researchers selected, engineered and optimized a bacteria strain and then successfully demonstrated its ability to convert CO2 into acetone and isopropanol (IPA). Not only does this new gas fermentation process remove greenhouse gases from the atmosphere, it also avoids using fossil fuels, which are typically needed to generate acetone and IPA. After performing life-cycle analysis, the team found the carbon-negative platform could reduce greenhouse gas emissions by 160% as compared to conventional processes, if widely adopted.
“The accelerating climate crisis, combined with rapid population growth, pose some of the most urgent challenges to humankind, all linked to the unabated release and accumulation of CO2 across the entire biosphere,” said Northwestern’s Michael Jewett, co-senior author of the study. “By harnessing our capacity to partner with biology to make what is needed, where and when it is needed, on a sustainable and renewable basis, we can begin to take advantage of the available CO2 to transform the bioeconomy.”
Jewett is the Walter P. Murphy Professor of Chemical and Biological Engineering at Northwestern’s McCormick School of Engineering and director of the Center for Synthetic Biology. He co-led the study with Michael Koepke and Ching Leang, both researchers at LanzaTech.
Necessary industrial bulk and platform chemicals, acetone and IPA are found nearly everywhere, with a combined global market topping $10 billion. Widely used as a disinfectant and antiseptic, IPA is the basis for one of the two World Health Organization-recommended sanitizer formulas, which are highly effective in killing the SARS-CoV-2 virus. And acetone is a solvent for many plastics and synthetic fibers, thinning polyester resin, cleaning tools and nail polish remover.
While these chemicals are incredibly useful, they are generated from fossil resources, leading to climate-warming CO2 emissions. To manufacture these chemicals more sustainably, the researchers developed a new gas fermentation process. They started with Clostridium autoethanogenum, an anaerobic bacterium engineered at LanzaTech. Then, the researchers used synthetic biology tools to reprogram the bacterium to ferment CO2 to make acetone and IPA.
“These innovations, led by cell-free strategies that guided both strain engineering and optimization of pathway enzymes, accelerated time to production by more than a year,” Jewett said.
The Northwestern and LanzaTech teams believe the developed strains and fermentation process will translate to industrial scale. The approach also could potentially be applied to create streamlined processes for generating other valuable chemicals.
Induced giant piezoelectricity in centrosymmetric oxides
by D.-S. Park, M. Hadad, L. M. Riemer, R. Ignatans, D. Spirito, V. Esposito, V. Tileli, N. Gauquelin, D. Chezganov, D. Jannis, J. Verbeeck, S. Gorfman, N. Pryds, P. Muralt, D. Damjanovic in Science
Piezoelectricity is used everywhere: Watches, cars, alarms, headphones, pickups for instruments, electric lighters and gas burners. One of the most common examples is probably the quartz watch, where the piezoelectric material quartz is a prerequisite for the watch’s function.
Piezoelectric materials have the particular property that their shape changes when applying an electrical voltage to the material. It also works the other way around: Exposing them to a mechanical impact will create an electrical voltage.
Piezoelectricity is often used in sensors, actuators, and resonators. In small devices, they are known as MEMS (micro-electromechanical systems). Here, materials other than quartz must be used. These materials, however, often contain lead in the form of lead zirconate titanate (PZT). This may prove to be a barrier to the spread of technology in, for example, the biomedical field, as lead is harmful to the body. However, researchers assess an excellent potential for utilizing the piezoelectric effect in a wider range of diagnostics, prognosis and therapy technologies if lead could be removed.
In a new article, Professor Nini Pryds and Professor Vincenzo Esposito from DTU Energy show that it is possible to create piezoelectric effects in materials where this is not ordinarily possible. It paves the way for designing piezoelectric materials that are lead-free and far more environmentally friendly. The research was conducted with colleagues from EPFL (École Polytechnique Fédérale de Lausanne), Tel Aviv University and the University of Antwerp. The work stems from the DTU-coordinated EU project Biowings, where several European partners are researching the development of new biomedical MEMS made with thin, lead-free films based on Gadolinium-doped oxide materials that are non-toxic and environmentally friendly. It is a great challenge, but the potential within, e.g. blood cell sorting, bacterial separation, and estimation of hematocrit levels are high.
“Many micro-electromechanical systems already exist, but they often contain lead-containing materials that are harmful for human implantation. The BioWings project aims to develop biocompatible materials with properties similar to common lead-containing materials that do not contain lead or the other harmful materials,” says Nini Pryds, adding:
“The new development will provide a fundamental step towards environmentally friendly piezoelectric materials with high performance for use, e.g. in car technology and medical applications,” says Nini Pryds.
As a fundamental premise, piezoelectric materials depend on crystal symmetry. Typical piezoelectric materials have a so-called non-centrosymmetric crystal lattice. This means, for example, that when one presses on the material, an electrical voltage naturally arises across the material due to the movement of positive and negative ions relative to each other. This results in the symmetry of the crystal being broken. For over a century, this has been a significant obstacle to finding new piezoelectric materials because piezoelectricity can only be created with a non-centrosymmetric crystal lattice.
One of the startling results of the new study is that a sizeable piezoelectric effect can be achieved with materials that do not usually allow it — i.e. centrosymmetric materials. Induction of piezoelectricity in centrosymmetric oxides can be achieved by using alternating current (AC) and direct current (DC) simultaneously. The field leads to the movement of positive and negative ion defects in the material relative to each other resulting in electric dipole or polarization. It breaks the crystal symmetry of the material, thereby achieving piezoelectricity in centrosymmetric crystals.
According to Nini Pryds, this concept will also be possible with other materials with similar atomic defects. It can thus help pave the way for non-lead-based piezoelectricity in, for example, actuators and sensors.
“For the time being, piezoelectric materials are limited to the non-centrosymmetric crystal structure. This entails a significant limitation in the number of materials that may be used. Our new results provide a paradigm shift towards inducing piezoelectricity in centrosymmetric crystals, thereby expanding the number of possible materials used. I expect it will have a significant effect on the design of new electromechanical devices with new biocompatible materials,” says Nini Pryds.
Dynamic body acceleration as a proxy to predict the cost of locomotion in bottlenose dolphins
by Austin S. Allen, Andrew J. Read, K. Alex Shorter, Joaquin Gabaldon, Ashley M. Blawas, Julie Rocho-Levine, Andreas Fahlman in Journal of Experimental Biology
From foraging for prey to evading predators, ship strikes or other dangers, a dolphin’s survival often hinges on being able to crank up the speed and shift its swimming into high gear. But burning all that rubber burns a lot of energy too, which, over time, can deplete reserves vital for growth, health and reproduction if the animal’s movements use more calories than it can take in.
Being able to estimate these energy costs of locomotion (COL) and determine where the metabolic tipping point might be is essential for answering fundamental questions about dolphin physiology and ecology, and for understanding the impacts of human disturbance on them. Because measuring costs of locomotion in dolphins in the wild is extremely difficult, past studies have estimated it based on the number of fluke stokes per minute. Since not all fluke strokes are the same size, it’s an imprecise measure of swimming effort.
A new Duke University-led study provides a more reliable way to estimate energy costs in dolphins by using overall dynamic body acceleration (ODBA), an integrated measure of all body motions a dolphin makes during swimming.
“Researchers have used movement tags to measure ODBA in other species, but this is the first published study calibrating ODBA with energy expenditure in multiple dolphins,” said study leader Austin Allen, a postdoctoral researcher in marine biology at Duke’s Nicholas School of the Environment.
As a proxy for measuring cost of locomotion in wild animals, Allen and his colleagues conducted swim trials on six trained bottlenose dolphins at Dolphin Quest, a zoological facility on Oahu, Hawaii, during May 2017, 2018, and 2019. Using a non-invasive device known as a pneumotachometer, they measured each dolphin’s oxygen consumption while at rest and immediately after it swam an 80-meter underwater lap across a lagoon. Non-invasive biologging tags were also used to record each animal’s three-dimensional body motions over each section of the trial — such as when it was slowing down to make a turn or speeding up mid-lap. By analyzing the collected data, a pattern began to emerge.
“There was some individual variation, but, overall, the results showed significant correlation between oxygen consumption and body acceleration, which suggests ODBA can be a reliable proxy for COL,” Allen said.
“Working with dolphins in zoos or aquariums is allowing us to use data we’ve already collected using these tags in the field to evaluate the cost of locomotion in wild populations,” he said.
Tunable metal hydroxide–organic frameworks for catalysing oxygen evolution
by Shuai Yuan, Jiayu Peng, Bin Cai, Zhehao Huang, Angel T. Garcia-Esparza, Dimosthenis Sokaras, Yirui Zhang, Livia Giordano, Karthik Akkiraju, Yun Guang Zhu, René Hübner, Xiaodong Zou, Yuriy Román-Leshkov, Yang Shao-Horn in Nature Materials
An electrochemical reaction that splits apart water molecules to produce oxygen is at the heart of multiple approaches aiming to produce alternative fuels for transportation. But this reaction has to be facilitated by a catalyst material, and today’s versions require the use of rare and expensive elements such as iridium, limiting the potential of such fuel production.
Now, researchers at MIT and elsewhere have developed an entirely new type of catalyst material, called a metal hydroxide-organic framework (MHOF), which is made of inexpensive and abundant components. The family of materials allows engineers to precisely tune the catalyst’s structure and composition to the needs of a particular chemical process, and it can then match or exceed the performance of conventional, more expensive catalysts. The findings are described in a paper by MIT postdoc Shuai Yuan, graduate student Jiayu Peng, Professor Yang Shao-Horn, Professor Yuriy Román-Leshkov, and nine others.
Oxygen evolution reactions are one of the reactions common to the electrochemical production of fuels, chemicals, and materials. These processes include the generation of hydrogen as a byproduct of the oxygen evolution, which can be used directly as a fuel or undergo chemical reactions to produce other transportation fuels; the manufacture of ammonia, for use as a fertilizer or chemical feedstock; and carbon dioxide reduction in order to control emissions.
But without help, “These reactions are sluggish,” Shao-Horn says. “For a reaction with slow kinetics, you have to sacrifice voltage or energy to promote the reaction rate.” Because of the extra energy input required, “The overall efficiency is low. So that’s why people use catalysts,” she says, as these materials naturally promote reactions by lowering energy input.
But until now, these catalysts “Aare all relying on expensive materials or late transition metals that are very scarce, for example iridium oxide, and there has been a big effort in the community to find alternatives based on Earth-abundant materials that have the same performance in terms of activity and stability,” Román-Leshkov says. The team says they have found materials that provide exactly that combination of characteristics.
Other teams have explored the use of metal hydroxides, such as nickel-iron hydroxides, Román-Leshkov says. But such materials have been difficult to tailor to the requirements of specific applications. Now, though, “The reason our work is quite exciting and quite relevant is that we’ve found a way of tailoring the properties by nanostructuring these metal hydroxides in a unique way.”
The team borrowed from research that has been done on a related class of compounds known as metal-organic frameworks (MOFs), which are a kind of crystalline structure made of metal oxide nodes linked together with organic linker molecules. By replacing the metal oxide in such materials with certain metal hydroxides, the team found, it became possible to create precisely tunable materials that also had the necessary stability to be potentially useful as catalysts.
“You put these chains of these organic linkers next to each other, and they actually direct the formation of metal hydroxide sheets that are interconnected with these organic linkers, which are then stacked, and have a higher stability,” Román-Leshkov says. This has multiple benefits, he says, by allowing a precise control over the nanostructured patterning, allowing precise control of the electronic properties of the metal, and also providing greater stability, enabling them to stand up to long periods of use.
In testing such materials, the researchers found the catalysts’ performance to be “surprising,” Shao-Horn says. “It is comparable to that of the state-of-the-art oxide materials catalyzing for the oxygen evolution reaction.”
Being composed largely of nickel and iron, these materials should be at least 100 times cheaper than existing catalysts, they say, although the team has not yet done a full economic analysis. This family of materials “really offers a new space to tune the active sites for catalyzing water splitting to produce hydrogen with reduced energy input,” Shao-Horn says, to meet the exact needs of any given chemical process where such catalysts are needed.
The materials can provide “five times greater tunability” than existing nickel-based catalysts, Peng says, simply by substituting different metals in place of nickel in the compound. “This would potentially offer many relevant avenues for future discoveries.” The materials can also be produced in extremely thin sheets, which could then be coated onto another material, further reducing the material costs of such systems.
So far, the materials have been tested in small-scale laboratory test devices, and the team is now addressing the issues of trying to scale up the process to commercially relevant scales, which could still take a few years. But the idea has great potential, Shao-Horn says, to help catalyze the production of clean, emissions-free hydrogen fuel, so that “we can bring down the cost of hydrogen from this process while not being constrained by the availability of precious metals. This is important, because we need hydrogen production technologies that can scale.”
Recovery of critical metals from EV batteries via thermal treatment and leaching with sulphuric acid at ambient temperature
by Martina Petranikova, Pol Llorach Naharro, Nathália Vieceli, Gabriele Lombardo, Burçak Ebin in Waste Management
Recycling of electric car batteries can be easier, cheaper, and more environmentally friendly, according to a new scientific article from Chalmers University of Technology, Sweden, which outlines an optimised recycling process. The research has been carried out by some of the world’s foremost experts in the field, and represents a vital step towards the electromobility society of the future.
As the use of electric vehicles (EVs) increases, recycling and recovery processes for EV batteries and the critical raw metals used in their production are becoming an increasingly important area of research. One method that currently attracts a lot of interest is a combination of thermal pretreatment and hydrometallurgy, in which aqueous chemistry is used to recover the metals. Several companies are developing systems that will use this combination, but the researchers at Chalmers University of Technology, Sweden, discovered that these companies use widely differing temperatures and times in their processes, and that there was a great need for a comparative study to determine the optimal thermal treatment and hydrometallurgical process for recycling lithium-ion batteries.
A key finding of the new study was that the hydrometallurgical process can be carried out at room temperature. This is something that has not been previously tested before, but can yield major benefits in the form of reduced environmental impacts and lower costs for recycling the batteries. The process can also be carried out significantly quicker than previously thought.
“Our research can make a huge difference for developers in this area. In some cases it can be as much as reducing the temperature from between 60 and 80 degrees Celsius, down to room temperature, and from several hours to just 30 minutes,” says Burcak Ebin, researcher at the Department for Chemistry and Chemical Engineering at Chalmers and one of the main authors of the article.
The researchers investigated how the different steps — thermal pretreatment and hydrometallurgy -are affected by each other. An important comparison was made between two different approaches to thermal pre-treatment — incineration or pyrolysis. The latter is without oxygen and is considered more environmentally friendly, and the researchers determined that this gave the best results.
“To meet the huge need for battery recycling that is coming, the processes currently in use must be made as effective and efficient as possible, so this study offers invaluable knowledge for the manufacturers and operators of this technology. The methods we present can also be used to optimise the recycling of all kinds of lithium-ion batteries,” explains Martina Petranikova, Associate Professor at the Department of Chemistry and Chemical Engineering at Chalmers, who has also worked with Northvolt, one of Europe’s largest battery manufacturers, helping to develop and implement their recycling processes.
If recycling of electric car batteries is to reach the volumes required for the future, the costs must be radically reduced. Improving the processes is therefore a crucial challenge.
“To reduce the costs, we need to cut the steps in the recycling process. We are working on several projects with that aim right now, and close collaborations and good communication between researchers and the developers of the technology will be extremely important for us to succeed with the challenges we face,” says Martina Petranikova.
An example of this is visible in connection to a new trend that has spread among the producers of EV batteries — solid state batteries. These batteries contain significantly more different metals, which makes the recycling much harder.
“As researchers we see a vital need to agree on a global standard for a maximum number of metals in these batteries,” says Martina Petranikova.
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