Tag Archives: supercapacitors

Seaweed battery

A supercapacitor is not a battery but it does have some similarities. (For the ‘seaweed curious’, there’s this somewhat related May 17, 2017 posting titled “Seaweed supercapacitors.” It doesn’t seem to be quite as popular as butterfly wings or a crustacean’s shell but seaweed does seem to have a following in the materials community. From an October 5, 2022 news item on Nanowerk,

Bristol-led team uses nanomaterials made from seaweed to create a strong battery separator, paving the way for greener and more efficient energy storage.

Sodium-metal batteries (SMBs) are one of the most promising high-energy and low-cost energy storage systems for the next-generation of large-scale applications. However, one of the major impediments to the development of SMBs is uncontrolled dendrite growth, which penetrate the battery’s separator and result in short-circuiting.

Building on previous work at the University of Bristol and in collaboration with Imperial College and University College London, the team has succeeded in making a separator from cellulose nanomaterials derived from brown seaweed.

An October 5, 2022 University of Bristol press release (also on EurekAlert), which originated the news item, gives some technical details, Note: A link has been removed,

The research, published in Advanced Materials, describes how fibres containing these seaweed-derived nanomaterials not only stop crystals from the sodium electrodes penetrating the separator, they also improve the performance of the batteries.

“The aim of a separator is to separate the functioning parts of a battery (the plus and the minus ends) and allow free transport of the charge. We have shown that seaweed-based materials can make the separator very strong and prevent it being punctured by metal structures made from sodium. It also allows for greater storage capacity and efficiency, increasing the lifetime of the batteries – something which is key to powering devices such as mobile phones for much longer,” said Jing Wang, first author and PhD student in the Bristol Composites Institute (BCI).

Dr Amaka Onyianta, also from the BCI, who created the cellulose nanomaterials and co-authored the research, said: “I was delighted to see that these nanomaterials are able to strengthen the separator materials and enhance our capability to move towards sodium-based batteries. This means we wouldn’t have to rely on scarce materials such as lithium, which is often mined unethically and uses a great deal of natural resources, such as water, to extract it.”

“This work really demonstrates that greener forms of energy storage are possible, without being destructive to the environment in their production,” said Professor Steve Eichhorn who led the research at the Bristol Composites Institute.

The next challenge is to upscale production of these materials and to supplant current lithium-based technology.

Here’s a link to and a citation for the paper,

Stable Sodium Metal Batteries in Carbonate Electrolytes Achieved by Bifunctional, Sustainable Separators with Tailored Alignment by Jing Wang, Zhen Xu, Qicheng Zhang, Xin Song, Xuekun Lu, Zhenyu Zhang, Amaka J. Onyianta, Mengnan Wang, Maria-Magdalena Titirici, Stephen J. Eichhorn. DOI: https://doi.org/10.1002/adma.202206367 First published online: 20 September 2022

This paper is open access.

A graphene-inorganic-hybrid micro-supercapacitor made of fallen leaves

I wonder if this means the end to leaf blowers. That is almost certainly wishful thinking as the researchers don’t seem to be concerned with how the leaves are gathered.

The schematic illustration of the production of femtosecond laser-induced graphene. Courtesy of KAIST

A January 27, 2022 news item on Nanowerk announces the work (Note: A link has been removed),

A KAIST [Korea Advanced Institute of Science and Technology] research team has developed graphene-inorganic-hybrid micro-supercapacitors made of fallen leaves using femtosecond laser direct laser writing (Advanced Functional Materials, “Green Flexible Graphene-Inorganic-Hybrid Micro-Supercapacitors Made of Fallen Leaves Enabled by Ultrafast Laser Pulses”).

A January 27, 2022 KAIST press release (also on EurekAlert but published January 26, 2022), which originated the news item, delves further into the research,

The rapid development of wearable electronics requires breakthrough innovations in flexible energy storage devices in which micro-supercapacitors have drawn a great deal of interest due to their high power density, long lifetimes, and short charging times. Recently, there has been an enormous increase in waste batteries owing to the growing demand and the shortened replacement cycle in consumer electronics. The safety and environmental issues involved in the collection, recycling, and processing of such waste batteries are creating a number of challenges.

Forests cover about 30 percent of the Earth’s surface and produce a huge amount of fallen leaves. This naturally occurring biomass comes in large quantities and is completely biodegradable, which makes it an attractive sustainable resource. Nevertheless, if the fallen leaves are left neglected instead of being used efficiently, they can contribute to fire hazards, air pollution, and global warming.

To solve both problems at once, a research team led by Professor Young-Jin Kim from the Department of Mechanical Engineering and Dr. Hana Yoon from the Korea Institute of Energy Research developed a novel technology that can create 3D porous graphene microelectrodes with high electrical conductivity by irradiating femtosecond laser pulses on the leaves in ambient air. This one-step fabrication does not require any additional materials or pre-treatment. 

They showed that this technique could quickly and easily produce porous graphene electrodes at a low price, and demonstrated potential applications by fabricating graphene micro-supercapacitors to power an LED and an electronic watch. These results open up a new possibility for the mass production of flexible and green graphene-based electronic devices.

Professor Young-Jin Kim said, “Leaves create forest biomass that comes in unmanageable quantities, so using them for next-generation energy storage devices makes it possible for us to reuse waste resources, thereby establishing a virtuous cycle.” 

This research was published in Advanced Functional Materials last month and was sponsored by the Ministry of Agriculture Food and Rural Affairs, the Korea Forest Service, and the Korea Institute of Energy Research.

Here’s a link to and a citation for the paper,

Green Flexible Graphene–Inorganic-Hybrid Micro-Supercapacitors Made of Fallen Leaves Enabled by Ultrafast Laser Pulses by Truong-Son Dinh Le, Yeong A. Lee, Han Ku Nam, Kyu Yeon Jang, Dongwook Yang, Byunggi Kim, Kanghoon Yim, Seung-Woo Kim, Hana Yoon, Young-Jin Kim. Advanced Functional Materials DOI: https://doi.org/10.1002/adfm.202107768 First published: 05 December 2021

This paper is behind a paywall.

Tamarind shells turned into carbon nanosheets for supercapacitors

Fro anyone who needs a shot of happiness, this is a very happy scientist,

Caption: Assistant Professor (Steve) Cuong Dang, from NTU’s School of Electrical and Electronic Engineering, who led the study, displaying pieces of tamarind shell, which were integral to the study. Credit to NTU Singapore

A July 14, 2021 news item on ScienceDaily describes the source of assistant professor (Steve) Cuong Dang’s happiness,

Shells of tamarind, a tropical fruit consumed worldwide, are discarded during food production. As they are bulky, tamarind shells take up a considerable amount of space in landfills where they are disposed as agricultural waste.

However, a team of international scientists led by Nanyang Technological University, Singapore (NTU Singapore) has found a way to deal with the problem. By processing the tamarind shells which are rich in carbon, the scientists converted the waste material into carbon nanosheets, which are a key component of supercapacitors – energy storage devices that are used in automobiles, buses, electric vehicles, trains, and elevators.

The study reflects NTU’s commitment to address humanity’s grand challenges on sustainability as part of its 2025 strategic plan, which seeks to accelerate the translation of research discoveries into innovations that mitigate our impact on the environment.

A July 14, 2021 NTU press release (also here [scroll down to click on the link to the full press release] and on EurekAlert but published July 13, 2021), which originated the news item, delves further into the topic,

he team, made up of researchers from NTU Singapore, the Western Norway University of Applied Sciences in Norway, and Alagappa University in India, believes that these nanosheets, when scaled up, could be an eco-friendly alternative to their industrially produced counterparts, and cut down on waste at the same time.

Assistant Professor (Steve) Cuong Dang, from NTU’s School of Electrical and Electronic Engineering, who led the study, said: “Through a series of analysis, we found that the performance of our tamarind shell-derived nanosheets was comparable to their industrially made counterparts in terms of porous structure and electrochemical properties. The process to make the nanosheets is also the standard method to produce active carbon nanosheets.”

Professor G. Ravi, Head, Department of Physics, who co-authored the study with Asst Prof Dr R. Yuvakkumar, who are both from Alagappa University, said: “The use of tamarind shells may reduce the amount of space required for landfills, especially in regions in Asia such as India, one of the world’s largest producers of tamarind, which is also grappling with waste disposal issues.”

The study was published in the peer-reviewed scientific journal Chemosphere in June [2021].

The step-by-step recipe for carbon nanosheets

To manufacture the carbon nanosheets, the researchers first washed tamarind fruit shells and dried them at 100°C for around six hours, before grinding them into powder.

The scientists then baked the powder in a furnace for 150 minutes at 700-900 degrees Celsius in the absence of oxygen to convert them into ultrathin sheets of carbon known as nanosheets.

Tamarind shells are rich in carbon and porous in nature, making them an ideal material from which to manufacture carbon nanosheets.

A common material used to produce carbon nanosheets are industrial hemp fibres. However, they require to be heated at over 180°C for 24 hours – four times longer than that of tamarind shells, and at a higher temperature. This is before the hemp is further subjected to intense heat to convert them into carbon nanosheets.

Professor Dhayalan Velauthapillai, Head of the research group for Advanced Nanomaterials for Clean Energy and Health Applications at Western Norway University of Applied Sciences, who participated in the study, said: “Carbon nanosheets comprise of layers of carbon atoms arranged in interconnecting hexagons, like a honeycomb. The secret behind their energy storing capabilities lies in their porous structure leading to large surface area which help the material to store large amounts of electric charges.”

The tamarind shell-derived nanosheets also showed good thermal stability and electric conductivity, making them promising options for energy storage.

The researchers hope to explore larger scale production of the carbon nanosheets with agricultural partners. They are also working on reducing the energy needed for the production process, making it more environmentally friendly, and are seeking to improve the electrochemical properties of the nanosheets.

The team also hopes to explore the possibility of using different types of fruit skins or shells to produce carbon nanosheets.

Here’s a link to and a citation for the paper,

Cleaner production of tamarind fruit shell into bio-mass derived porous 3D-activated carbon nanosheets by CVD technique for supercapacitor applications by V. Thirumal, K. Dhamodharan, R. Yuvakkumar, G. Ravi, B. Saravanakumar, M. Thambidurai, Cuong Dang, Dhayalan Velauthapillai. Chemosphere Volume 282, November 2021, 131033 DOI: https://doi.org/10.1016/j.chemosphere.2021.131033 Available online 2 June 2021.

This paper is behind a paywall.

Because we could all do with a little more happiness these days,

Caption: (L-R) Senior Research Fellow Dr Thambidurai Mariyappan, also from NTU’s School of Electrical and Electronic Engineering, who was part of the study, and Asst Prof Dang, holding up tamarind pods. Credit to NTU Singapore

Graphene-based material for high-performance supercapacitors

Researchers from Russia and France have developed a new material, based on graphene, that would allow supercapacitors to store more energy according to a January 15, 2021 news item on Nanowerk,

Scientists of Tomsk Polytechnic University jointly with colleagues from the University of Lille (Lille, France) synthetized a new material based on reduced graphene oxide (rGO) for supercapacitors, energy storage devices. The rGO modification method with the use of organic molecules, derivatives of hypervalent iodine, allowed obtaining a material that stores 1.7 times more electrical energy.

Photo: modified rGO supercapacitor electrodes. Courtesy: Tomsk University

A January 15, 2020 Tomsk Polytechnic University press release (also on EurekAlert), which originated the news item, provides more details,

A supercapacitor is an electrochemical device for storage and release of electric charge. Unlike batteries, they store and release energy several times faster and do not contain lithium.

A supercapacitor is an element with two electrodes separated by an organic or inorganic electrolyte. The electrodes are coated with an electric charge accumulating material. The modern trend in science is to use various materials based on graphene, one of the thinnest and most durable materials known to man. The researchers of TPU and the University of Lille used reduced graphene oxide (rGO), a cheap and available material.

“Despite their potential, supercapacitors are not wide-spread yet. For further development of the technology, it is required to enhance the efficiency of supercapacitors. One of the key challenges here is to increase the energy capacity.

It can be achieved by expanding the surface area of an energy storage material, rGO in this particular case. We found a simple and quite fast method. We used exceptionally organic molecules under mild conditions and did not use expensive and toxic metals,” Pavel Postnikov, Associate Professor of TPU Research School of Chemistry and Applied Biomedical Science and the research supervisor says.

Reduced graphene oxide in a powder form is deposited on electrodes. As a result, the electrode becomes coated with hundreds of nanoscale layers of the substance. The layers tend to agglomerate, in other words, to sinter. To expand the surface area of a material, the interlayer spacing should be increased.

“For this purpose, we modified rGO with organic molecules, which resulted in the interlayer spacing increase. Insignificant differences in interlayer spacing allowed increasing energy capacity of the material by 1.7 times. That is, 1 g of the new material can store 1.7 times more energy in comparison with a pristine reduced graphene oxide,” Elizaveta Sviridova, Junior Research Fellow of TPU Research School of Chemistry and Applied Biomedical Sciences and one of the authors of the article explains.

The reaction proceeded through the formation of active arynes from iodonium salts. They kindle scientists` interest due to their property to form a single layer of new organic groups on material surfaces. The TPU researchers have been developing the chemistry of iodonium salts for many years.

“The modification reaction proceeds under mild conditions by simply mixing the solution of iodonium salt with reduced graphene oxide. If we compare it with other methods of reduced graphene oxide functionalization, we have achieved the highest indicators of material energy capacity increase,” Elizaveta Sviridova says.

Here’s a link to and a citation for the paper,

Aryne cycloaddition reaction as a facile and mild modification method for design of electrode materials for high-performance symmetric supercapacitor by Elizaveta Sviridova, Min Li, Alexandre Barras, Ahmed Addad, Mekhman S.Yusubov, Viktor V. Zhdankin, Akira Yoshimura, Sabine Szunerits, Pavel S. Postnikov, Rabah Boukherroub. Electrochimica Acta Volume 369, 10 February 2021, 137667 DOI: https://doi.org/10.1016/j.electacta.2020.137667

This paper is behind a paywall.

New capacitor for better wearable electronics?

Supercapacitors are a predictable source of scientific interest and excitement. The latest entry in the ‘supercapacitor stakes’ is from a Russian/Finnish/US team according to a June 11, 2020 Skoltech (Skolkovo Institute of Science and Technology) press release (also on EurekAlert),

Researchers from Skoltech [Russia], Aalto University [Finland] and Massachusetts Institute of Technology [MIT; US] have designed a high-performance, low-cost, environmentally friendly, and stretchable supercapacitor that can potentially be used in wearable electronics. The paper was published in the Journal of Energy Storage.

Supercapacitors, with their high power density, fast charge-discharge rates, long cycle life, and cost-effectiveness, are a promising power source for everything from mobile and wearable electronics to electric vehicles. However, combining high energy density, safety, and eco-friendliness in one supercapacitor suitable for small devices has been rather challenging.

“Usually, organic solvents are used to increase the energy density. These are hazardous, not environmentally friendly, and they reduce the power density compared to aqueous electrolytes with higher conductivity,” says Professor Tanja Kallio from Aalto University, a co-author of the paper.

The researchers proposed a new design for a “green” and simple-to-fabricate supercapacitor. It consists of a solid-state material based on nitrogen-doped graphene flake electrodes distributed in the NaCl-containing hydrogel electrolyte. This structure is sandwiched between two single-walled carbon nanotube film current collectors, which provides stretchability. Hydrogel in the supercapacitor design enables compact packing and high energy density and allows them to use the environmentally friendly electrolyte.

The scientists managed to improve the volumetric capacitive performance, high energy density and power density for the prototype over analogous supercapacitors described in previous research. “We fabricated a prototype with unchanged performance under the 50% strain after a thousand stretching cycles. To ensure lower cost and better environmental performance, we used a NaCl-based electrolyte. Still the fabrication cost can be lowered down by implementation of 3D printing or other advanced fabrication techniques,” concluded Skoltech professor Albert Nasibulin.

Here’s a link to and a citation for the paper,

Superior environmentally friendly stretchable supercapacitor based on nitrogen-doped graphene/hydrogel and single-walled carbon nanotubes by Evgeniia Gilshtein, Cristina Flox, Farhan S.M. Ali, Bahareh Mehrabimatin, Fedor S.Fedorov, Shaoting Lin, Xuanhe Zhao, Albert G. Nasibulin, Tanja Kallio. Journal of Energy Storage Volume 30, August 2020, 101505 DOI: https://doi.org/10.1016/j.est.2020.101505

This paper is behind a paywall.

I’m trying to remember if I’ve ever before seen a material that combines graphene and single-walled carbon nanotubes (SWCNTs). Anyway, here’s an image the researchers are using illustrate their work,

Caption: This is an outline of the new supercapacitor. Credit: Pavel Odinev / Skoltech

Wearable electronic textiles from the UK, India, and Canada: two different carbon materials

It seems wearable electronic textiles may be getting nearer to the marketplace. I have three research items (two teams working with graphene and one working with carbon nanotubes) that appeared on my various feeds within two days of each other.

UK/China

This research study is the result of a collaboration between UK and Chinese scientists. From a May 15, 2019 news item on phys.org (Note: Links have been removed),


Wearable electronic components incorporated directly into fabrics have been developed by researchers at the University of Cambridge. The devices could be used for flexible circuits, healthcare monitoring, energy conversion, and other applications.

The Cambridge researchers, working in collaboration with colleagues at Jiangnan University in China, have shown how graphene – a two-dimensional form of carbon – and other related materials can be directly incorporated into fabrics to produce charge storage elements such as capacitors, paving the way to textile-based power supplies which are washable, flexible and comfortable to wear.

The research, published in the journal Nanoscale, demonstrates that graphene inks can be used in textiles able to store electrical charge and release it when required. The new textile electronic devices are based on low-cost, sustainable and scalable dyeing of polyester fabric. The inks are produced by standard solution processing techniques.

Building on previous work by the same team, the researchers designed inks which can be directly coated onto a polyester fabric in a simple dyeing process. The versatility of the process allows various types of electronic components to be incorporated into the fabric.

Schematic of the textile-based capacitor integrating GNP/polyesters as electrodes and h-BN/polyesters as dielectrics. Credit: Felice Torrisi

A May 16, 2019 University of Cambridge press release, which originated the news item, probes further,

Most other wearable electronics rely on rigid electronic components mounted on plastic or textiles. These offer limited compatibility with the skin in many circumstances, are damaged when washed and are uncomfortable to wear because they are not breathable.

“Other techniques to incorporate electronic components directly into textiles are expensive to produce and usually require toxic solvents, which makes them unsuitable to be worn,” said Dr Felice Torrisi from the Cambridge Graphene Centre, and the paper’s corresponding author. “Our inks are cheap, safe and environmentally-friendly, and can be combined to create electronic circuits by simply overlaying different fabrics made of two-dimensional materials on the fabric.”

The researchers suspended individual graphene sheets in a low boiling point solvent, which is easily removed after deposition on the fabric, resulting in a thin and uniform conducting network made up of multiple graphene sheets. The subsequent overlay of several graphene and hexagonal boron nitride (h-BN) fabrics creates an active region, which enables charge storage. This sort of ‘battery’ on fabric is bendable and can withstand washing cycles in a normal washing machine.

“Textile dyeing has been around for centuries using simple pigments, but our result demonstrates for the first time that inks based on graphene and related materials can be used to produce textiles that could store and release energy,” said co-author Professor Chaoxia Wang from Jiangnan University in China. “Our process is scalable and there are no fundamental obstacles to the technological development of wearable electronic devices both in terms of their complexity and performance.”

The work done by the Cambridge researchers opens a number of commercial opportunities for ink based on two-dimensional materials, ranging from personal health and well-being technology, to wearable energy and data storage, military garments, wearable computing and fashion.

“Turning textiles into functional energy storage elements can open up an entirely new set of applications, from body-energy harvesting and storage to the Internet of Things,” said Torrisi “In the future our clothes could incorporate these textile-based charge storage elements and power wearable textile devices.”

Here’s a link to and a citation for the paper,

Wearable solid-state capacitors based on two-dimensional material all-textile heterostructures by Siyu Qiang, Tian Carey, Adrees Arbab, Weihua Song, Chaoxia Wang and Felice Torris. Nanoscale, 2019, Advance Article DOI: 10.1039/C9NR00463G First published on 18 Apr 2019

This paper is behind a paywall.

India

Prior to graphene’s reign as the ‘it’ carbon material, carbon nanotubes (CNTs) ruled. It’s been quieter on the CNT front since graphene took over but a May 15, 2019 Nanowerk Spotlight article by Michael Berger highlights some of the latest CNT research coming out of India,


The most important technical challenge is to blend the chemical nature of raw materials with fabrication techniques and processability, all of which are diametrically conflicting for textiles and conventional energy storage devices. A team from Indian Institute of Technology Bombay has come out with a comprehensive approach involving simple and facile steps to fabricate a wearable energy storage device. Several scientific and technological challenges were overcome during this process.

First, to achieve user-comfort and computability with clothing, the scaffold employed was the the same as what a regular fabric is made up of – cellulose fibers. However, cotton yarns are electrical insulators and therefore practically useless for any electronics. Therefore, the yarns are coated with single-wall carbon nanotubes (SWNTs).

SWNTs are hollow, cylindrical allotropes of carbon and combine excellent mechanical strength with electrical conductivity and surface area. Such a coating converts the electrical insulating cotton yarn to a metallic conductor with high specific surface area. At the same time, using carbon-based materials ensures that the final material remains light-weight and does not cause user discomfort that can arise from metallic wires such as copper and gold. This CNT-coated cotton yarn (CNT-wires) forms the electrode for the energy storage device.

Next, the electrolyte is composed of solid-state electrolyte sheets since no liquid-state electrolytes can be used for this purpose. However, solid state electrolytes suffer from poor ionic conductivity – a major disadvantage for energy storage applications. Therefore, a steam-based infiltration approach that enhances the ionic conductivity of the electrolyte is adopted. Such enhancement of humidity significantly increases the energy storage capacity of the device.


The integration of the CNT-wire electrode with the electrolyte sheet was carried out by a simple and elegant approach of interweaving the CNT-wire through the electrolyte (see Figure 1). This resulted in cross-intersections which are actually junctions where the electrical energy can be stored. Each such junction is now an energy storage unit, referred to as sewcap.

The advantage of this process is that several 100s and 1000s of sewcaps can be made in a small area and integrated to increase the total amount of energy stored in the system. This scalability is unique and critical aspect of this work and stems from the approach of interweaving.

Further, this process is completely adaptable with current processes used in textile industries. Hence, a proportionately large energy-storage is achieved by creating sewcap-junctions in various combinations.

All components of the final sewcap device are flexible. However, they need to be protected from environmental effects such as temperature, humidity and sweat while retaining the mechanical flexibility. This is achieved by laminating the entire device between polymer sheets. The process is exactly similar to the one used for protecting documents and ID cards.

The laminated sewcap can be integrated easily on clothing and fabrics while retaining the flexibility and sturdiness. This is demonstrated by the unchanged performance of the device during extreme and harsh mechanical testing such as striking repeatedly with a hammer, complete flexing, bending and rolling and washing in a laundry machine.

In fact, this is the first device that has been proven to be stable under rigorous washing conditions in the presence of hot water, detergents and high torque (spinning action of washing machine). This provides the device with comprehensive mechanical stability.


CNTs have high surface area and electrical conductivity. The CNT-wire combines these properties of CNTs with stability and porosity of cellulose yarns. The junction created by interweaving is essentially comprised of two such CNT-wires that are sandwiching an electrolyte. Application of potential difference leads to polarization of the electrolyte thus enabling energy storage similar to the way in which a conventional capacitor acts.

“We use the advantage of the interweaving process and create several such junctions. So, with each junction being able to store a certain amount of electrical energy, all the junctions synchronized are able to store a large amount of energy. This provides high energy density to the device,” Prof. C. Subramaniam, Department of Chemistry, IIT Bombay and corresponding author of the paper points out.

The device has also been employed for lighting up an LED [light-emitting diode]. This can be potentially scaled to provide electrical energy demanded by the application.

This image accompanies the paper written by Prof. C. Subramaniam and his team,

Courtesy: IACS Applied Materials Interfaces

Here’s a link to and a citation for the paper,

Interwoven Carbon Nanotube Wires for High-Performing, Mechanically Robust, Washable, and Wearable Supercapacitors by Mihir Kumar Jha, Kenji Hata, and Chandramouli Subramaniam. ACS Appl. Mater. Interfaces, Article ASAP DOI: 10.1021/acsami.8b22233 Publication Date (Web): April 29, 2019 Copyright © 2019 American Chemical Society

This paper is behind a paywall.

Canada

A research team from the University of British Columbia (UBC at the Okanagan Campus) joined the pack with a May 16, 2019 news item on ScienceDaily,

Forget the smart watch. Bring on the smart shirt.

Researchers at UBC Okanagan’s School of Engineering have developed a low-cost sensor that can be interlaced into textiles and composite materials. While the research is still new, the sensor may pave the way for smart clothing that can monitor human movement.

A May 16, 2019 UBC news release (also on EurekAlert), which originated the news item, describes the work in more detail,


“Microscopic sensors are changing the way we monitor machines and humans,” says Hoorfar, lead researcher at the Advanced Thermo-Fluidic Lab at UBC’s Okanagan campus. “Combining the shrinking of technology along with improved accuracy, the future is very bright in this area.”

This ‘shrinking technology’ uses a phenomenon called piezo-resistivity—an electromechanical response of a material when it is under strain. These tiny sensors have shown a great promise in detecting human movements and can be used for heart rate monitoring or temperature control, explains Hoorfar.

Her research, conducted in partnership with UBC Okanagan’s Materials and Manufacturing Research Institute, shows the potential of a low-cost, sensitive and stretchable yarn sensor. The sensor can be woven into spandex material and then wrapped into a stretchable silicone sheath. This sheath protects the conductive layer against harsh conditions and allows for the creation of washable wearable sensors.

While the idea of smart clothing—fabrics that can tell the user when to hydrate, or when to rest—may change the athletics industry, UBC Professor Abbas Milani says the sensor has other uses. It can monitor deformations in fibre-reinforced composite fabrics currently used in advanced industries such as automotive, aerospace and marine manufacturing.

The low-cost stretchable composite sensor has also shown a high sensitivity and can detect small deformations such as yarn stretching as well as out-of-plane deformations at inaccessible places within composite laminates, says Milani, director of the UBC Materials and Manufacturing Research Institute.

The testing indicates that further improvements in its accuracy could be achieved by fine-tuning the sensor’s material blend and improving its electrical conductivity and sensitivity This can eventually make it able to capture major flaws like “fibre wrinkling” during the manufacturing of advanced composite structures such as those currently used in airplanes or car bodies.

“Advanced textile composite materials make the most of combining the strengths of different reinforcement materials and patterns with different resin options,” he says. “Integrating sensor technologies like piezo-resistive sensors made of flexible materials compatible with the host textile reinforcement is becoming a real game-changer in the emerging era of smart manufacturing and current automated industry trends.”

Here’s a link to and a citation for the paper,

Graphene‐Coated Spandex Sensors Embedded into Silicone Sheath for Composites Health Monitoring and Wearable Applications by Hossein Montazerian, Armin Rashidi, Arash Dalili, Homayoun Najjaran, Abbas S. Milani, Mina Hoorfar. Small Volume15, Issue17 April 26, 2019 1804991 DOI: https://doi.org/10.1002/smll.201804991 First published: 28 March 2019

This paper is behind a paywall.

Will there be one winner or will they find CNTs better for one type of wearable tech textile while graphene excels for another type of wearable tech textile?

It’s a very ‘carbony’ time: graphene jacket, graphene-skinned airplane, and schwarzite

In August 2018, I been stumbled across several stories about graphene-based products and a new form of carbon.

Graphene jacket

The company producing this jacket has as its goal “… creating bionic clothing that is both bulletproof and intelligent.” Well, ‘bionic‘ means biologically-inspired engineering and ‘intelligent‘ usually means there’s some kind of computing capability in the product. This jacket, which is the first step towards the company’s goal, is not bionic, bulletproof, or intelligent. Nonetheless, it represents a very interesting science experiment in which you, the consumer, are part of step two in the company’s R&D (research and development).

Onto Vollebak’s graphene jacket,

Courtesy: Vollebak

From an August 14, 2018 article by Jesus Diaz for Fast Company,

Graphene is the thinnest possible form of graphite, which you can find in your everyday pencil. It’s purely bi-dimensional, a single layer of carbon atoms that has unbelievable properties that have long threatened to revolutionize everything from aerospace engineering to medicine. …

Despite its immense promise, graphene still hasn’t found much use in consumer products, thanks to the fact that it’s hard to manipulate and manufacture in industrial quantities. The process of developing Vollebak’s jacket, according to the company’s cofounders, brothers Steve and Nick Tidball, took years of intensive research, during which the company worked with the same material scientists who built Michael Phelps’ 2008 Olympic Speedo swimsuit (which was famously banned for shattering records at the event).

The jacket is made out of a two-sided material, which the company invented during the extensive R&D process. The graphene side looks gunmetal gray, while the flipside appears matte black. To create it, the scientists turned raw graphite into something called graphene “nanoplatelets,” which are stacks of graphene that were then blended with polyurethane to create a membrane. That, in turn, is bonded to nylon to form the other side of the material, which Vollebak says alters the properties of the nylon itself. “Adding graphene to the nylon fundamentally changes its mechanical and chemical properties–a nylon fabric that couldn’t naturally conduct heat or energy, for instance, now can,” the company claims.

The company says that it’s reversible so you can enjoy graphene’s properties in different ways as the material interacts with either your skin or the world around you. “As physicists at the Max Planck Institute revealed, graphene challenges the fundamental laws of heat conduction, which means your jacket will not only conduct the heat from your body around itself to equalize your skin temperature and increase it, but the jacket can also theoretically store an unlimited amount of heat, which means it can work like a radiator,” Tidball explains.

He means it literally. You can leave the jacket out in the sun, or on another source of warmth, as it absorbs heat. Then, the company explains on its website, “If you then turn it inside out and wear the graphene next to your skin, it acts like a radiator, retaining its heat and spreading it around your body. The effect can be visibly demonstrated by placing your hand on the fabric, taking it away and then shooting the jacket with a thermal imaging camera. The heat of the handprint stays long after the hand has left.”

There’s a lot more to the article although it does feature some hype and I’m not sure I believe Diaz’s claim (August 14, 2018 article) that ‘graphene-based’ hair dye is perfectly safe ( Note: A link has been removed),

Graphene is the thinnest possible form of graphite, which you can find in your everyday pencil. It’s purely bi-dimensional, a single layer of carbon atoms that has unbelievable properties that will one day revolutionize everything from aerospace engineering to medicine. Its diverse uses are seemingly endless: It can stop a bullet if you add enough layers. It can change the color of your hair with no adverse effects. [emphasis mine] It can turn the walls of your home into a giant fire detector. “It’s so strong and so stretchy that the fibers of a spider web coated in graphene could catch a falling plane,” as Vollebak puts it in its marketing materials.

Not unless things have changed greatly since March 2018. My August 2, 2018 posting featured the graphene-based hair dye announcement from March 2018 and a cautionary note from Dr. Andrew Maynard (scroll down ab out 50% of the way for a longer excerpt of Maynard’s comments),

Northwestern University’s press release proudly announced, “Graphene finds new application as nontoxic, anti-static hair dye.” The announcement spawned headlines like “Enough with the toxic hair dyes. We could use graphene instead,” and “’Miracle material’ graphene used to create the ultimate hair dye.”

From these headlines, you might be forgiven for getting the idea that the safety of graphene-based hair dyes is a done deal. Yet having studied the potential health and environmental impacts of engineered nanomaterials for more years than I care to remember, I find such overly optimistic pronouncements worrying – especially when they’re not backed up by clear evidence.

These studies need to be approached with care, as the precise risks of graphene exposure will depend on how the material is used, how exposure occurs and how much of it is encountered. Yet there’s sufficient evidence to suggest that this substance should be used with caution – especially where there’s a high chance of exposure or that it could be released into the environment.

The full text of Dr. Maynard’s comments about graphene hair dyes and risk can be found here.

Bearing in mind  that graphene-based hair dye is an entirely different class of product from the jacket, I wouldn’t necessarily dismiss risks; I would like to know what kind of risk assessment and safety testing has been done. Due to their understandable enthusiasm, the brothers Tidball have focused all their marketing on the benefits and the opportunity for the consumer to test their product (from graphene jacket product webpage),

While it’s completely invisible and only a single atom thick, graphene is the lightest, strongest, most conductive material ever discovered, and has the same potential to change life on Earth as stone, bronze and iron once did. But it remains difficult to work with, extremely expensive to produce at scale, and lives mostly in pioneering research labs. So following in the footsteps of the scientists who discovered it through their own highly speculative experiments, we’re releasing graphene-coated jackets into the world as experimental prototypes. Our aim is to open up our R&D and accelerate discovery by getting graphene out of the lab and into the field so that we can harness the collective power of early adopters as a test group. No-one yet knows the true limits of what graphene can do, so the first edition of the Graphene Jacket is fully reversible with one side coated in graphene and the other side not. If you’d like to take part in the next stage of this supermaterial’s history, the experiment is now open. You can now buy it, test it and tell us about it. [emphasis mine]

How maverick experiments won the Nobel Prize

While graphene’s existence was first theorised in the 1940s, it wasn’t until 2004 that two maverick scientists, Andre Geim and Konstantin Novoselov, were able to isolate and test it. Through highly speculative and unfunded experimentation known as their ‘Friday night experiments,’ they peeled layer after layer off a shaving of graphite using Scotch tape until they produced a sample of graphene just one atom thick. After similarly leftfield thinking won Geim the 2000 Ig Nobel prize for levitating frogs using magnets, the pair won the Nobel prize in 2010 for the isolation of graphene.

Should you be interested, in beta-testing the jacket, it will cost you $695 (presumably USD); order here. One last thing, Vollebak is based in the UK.

Graphene skinned plane

An August 14, 2018 news item (also published as an August 1, 2018 Haydale press release) by Sue Keighley on Azonano heralds a new technology for airplans,

Haydale, (AIM: HAYD), the global advanced materials group, notes the announcement made yesterday from the University of Central Lancashire (UCLAN) about the recent unveiling of the world’s first graphene skinned plane at the internationally renowned Farnborough air show.

The prepreg material, developed by Haydale, has potential value for fuselage and wing surfaces in larger scale aero and space applications especially for the rapidly expanding drone market and, in the longer term, the commercial aerospace sector. By incorporating functionalised nanoparticles into epoxy resins, the electrical conductivity of fibre-reinforced composites has been significantly improved for lightning-strike protection, thereby achieving substantial weight saving and removing some manufacturing complexities.

Before getting to the photo, here’s a definition for pre-preg from its Wikipedia entry (Note: Links have been removed),

Pre-preg is “pre-impregnated” composite fibers where a thermoset polymer matrix material, such as epoxy, or a thermoplastic resin is already present. The fibers often take the form of a weave and the matrix is used to bond them together and to other components during manufacture.

Haydale has supplied graphene enhanced prepreg material for Juno, a three-metre wide graphene-enhanced composite skinned aircraft, that was revealed as part of the ‘Futures Day’ at Farnborough Air Show 2018. [downloaded from https://www.azonano.com/news.aspx?newsID=36298]

A July 31, 2018 University of Central Lancashire (UCLan) press release provides a tiny bit more (pun intended) detail,

The University of Central Lancashire (UCLan) has unveiled the world’s first graphene skinned plane at an internationally renowned air show.

Juno, a three-and-a-half-metre wide graphene skinned aircraft, was revealed on the North West Aerospace Alliance (NWAA) stand as part of the ‘Futures Day’ at Farnborough Air Show 2018.

The University’s aerospace engineering team has worked in partnership with the Sheffield Advanced Manufacturing Research Centre (AMRC), the University of Manchester’s National Graphene Institute (NGI), Haydale Graphene Industries (Haydale) and a range of other businesses to develop the unmanned aerial vehicle (UAV), which also includes graphene batteries and 3D printed parts.

Billy Beggs, UCLan’s Engineering Innovation Manager, said: “The industry reaction to Juno at Farnborough was superb with many positive comments about the work we’re doing. Having Juno at one the world’s biggest air shows demonstrates the great strides we’re making in leading a programme to accelerate the uptake of graphene and other nano-materials into industry.

“The programme supports the objectives of the UK Industrial Strategy and the University’s Engineering Innovation Centre (EIC) to increase industry relevant research and applications linked to key local specialisms. Given that Lancashire represents the fourth largest aerospace cluster in the world, there is perhaps no better place to be developing next generation technologies for the UK aerospace industry.”

Previous graphene developments at UCLan have included the world’s first flight of a graphene skinned wing and the launch of a specially designed graphene-enhanced capsule into near space using high altitude balloons.

UCLan engineering students have been involved in the hands-on project, helping build Juno on the Preston Campus.

Haydale supplied much of the material and all the graphene used in the aircraft. Ray Gibbs, Chief Executive Officer, said: “We are delighted to be part of the project team. Juno has highlighted the capability and benefit of using graphene to meet key issues faced by the market, such as reducing weight to increase range and payload, defeating lightning strike and protecting aircraft skins against ice build-up.”

David Bailey Chief Executive of the North West Aerospace Alliance added: “The North West aerospace cluster contributes over £7 billion to the UK economy, accounting for one quarter of the UK aerospace turnover. It is essential that the sector continues to develop next generation technologies so that it can help the UK retain its competitive advantage. It has been a pleasure to support the Engineering Innovation Centre team at the University in developing the world’s first full graphene skinned aircraft.”

The Juno project team represents the latest phase in a long-term strategic partnership between the University and a range of organisations. The partnership is expected to go from strength to strength following the opening of the £32m EIC facility in February 2019.

The next step is to fly Juno and conduct further tests over the next two months.

Next item, a new carbon material.

Schwarzite

I love watching this gif of a schwarzite,

The three-dimensional cage structure of a schwarzite that was formed inside the pores of a zeolite. (Graphics by Yongjin Lee and Efrem Braun)

An August 13, 2018 news item on Nanowerk announces the new carbon structure,

The discovery of buckyballs [also known as fullerenes, C60, or buckminsterfullerenes] surprised and delighted chemists in the 1980s, nanotubes jazzed physicists in the 1990s, and graphene charged up materials scientists in the 2000s, but one nanoscale carbon structure – a negatively curved surface called a schwarzite – has eluded everyone. Until now.

University of California, Berkeley [UC Berkeley], chemists have proved that three carbon structures recently created by scientists in South Korea and Japan are in fact the long-sought schwarzites, which researchers predict will have unique electrical and storage properties like those now being discovered in buckminsterfullerenes (buckyballs or fullerenes for short), nanotubes and graphene.

An August 13, 2018 UC Berkeley news release by Robert Sanders, which originated the news item, describes how the Berkeley scientists and the members of their international  collaboration from Germany, Switzerland, Russia, and Italy, have contributed to the current state of schwarzite research,

The new structures were built inside the pores of zeolites, crystalline forms of silicon dioxide – sand – more commonly used as water softeners in laundry detergents and to catalytically crack petroleum into gasoline. Called zeolite-templated carbons (ZTC), the structures were being investigated for possible interesting properties, though the creators were unaware of their identity as schwarzites, which theoretical chemists have worked on for decades.

Based on this theoretical work, chemists predict that schwarzites will have unique electronic, magnetic and optical properties that would make them useful as supercapacitors, battery electrodes and catalysts, and with large internal spaces ideal for gas storage and separation.

UC Berkeley postdoctoral fellow Efrem Braun and his colleagues identified these ZTC materials as schwarzites based of their negative curvature, and developed a way to predict which zeolites can be used to make schwarzites and which can’t.

“We now have the recipe for how to make these structures, which is important because, if we can make them, we can explore their behavior, which we are working hard to do now,” said Berend Smit, an adjunct professor of chemical and biomolecular engineering at UC Berkeley and an expert on porous materials such as zeolites and metal-organic frameworks.

Smit, the paper’s corresponding author, Braun and their colleagues in Switzerland, China, Germany, Italy and Russia will report their discovery this week in the journal Proceedings of the National Academy of Sciences. Smit is also a faculty scientist at Lawrence Berkeley National Laboratory.

Playing with carbon

Diamond and graphite are well-known three-dimensional crystalline arrangements of pure carbon, but carbon atoms can also form two-dimensional “crystals” — hexagonal arrangements patterned like chicken wire. Graphene is one such arrangement: a flat sheet of carbon atoms that is not only the strongest material on Earth, but also has a high electrical conductivity that makes it a promising component of electronic devices.

schwarzite carbon cage

The cage structure of a schwarzite that was formed inside the pores of a zeolite. The zeolite is subsequently dissolved to release the new material. (Graphics by Yongjin Lee and Efrem Braun)

Graphene sheets can be wadded up to form soccer ball-shaped fullerenes – spherical carbon cages that can store molecules and are being used today to deliver drugs and genes into the body. Rolling graphene into a cylinder yields fullerenes called nanotubes, which are being explored today as highly conductive wires in electronics and storage vessels for gases like hydrogen and carbon dioxide. All of these are submicroscopic, 10,000 times smaller than the width of a human hair.

To date, however, only positively curved fullerenes and graphene, which has zero curvature, have been synthesized, feats rewarded by Nobel Prizes in 1996 and 2010, respectively.

In the 1880s, German physicist Hermann Schwarz investigated negatively curved structures that resemble soap-bubble surfaces, and when theoretical work on carbon cage molecules ramped up in the 1990s, Schwarz’s name became attached to the hypothetical negatively curved carbon sheets.

“The experimental validation of schwarzites thus completes the triumvirate of possible curvatures to graphene; positively curved, flat, and now negatively curved,” Braun added.

Minimize me

Like soap bubbles on wire frames, schwarzites are topologically minimal surfaces. When made inside a zeolite, a vapor of carbon-containing molecules is injected, allowing the carbon to assemble into a two-dimensional graphene-like sheet lining the walls of the pores in the zeolite. The surface is stretched tautly to minimize its area, which makes all the surfaces curve negatively, like a saddle. The zeolite is then dissolved, leaving behind the schwarzite.

soap bubble schwarzite structure

A computer-rendered negatively curved soap bubble that exhibits the geometry of a carbon schwarzite. (Felix Knöppel image)

“These negatively-curved carbons have been very hard to synthesize on their own, but it turns out that you can grow the carbon film catalytically at the surface of a zeolite,” Braun said. “But the schwarzites synthesized to date have been made by choosing zeolite templates through trial and error. We provide very simple instructions you can follow to rationally make schwarzites and we show that, by choosing the right zeolite, you can tune schwarzites to optimize the properties you want.”

Researchers should be able to pack unusually large amounts of electrical charge into schwarzites, which would make them better capacitors than conventional ones used today in electronics. Their large interior volume would also allow storage of atoms and molecules, which is also being explored with fullerenes and nanotubes. And their large surface area, equivalent to the surface areas of the zeolites they’re grown in, could make them as versatile as zeolites for catalyzing reactions in the petroleum and natural gas industries.

Braun modeled ZTC structures computationally using the known structures of zeolites, and worked with topological mathematician Senja Barthel of the École Polytechnique Fédérale de Lausanne in Sion, Switzerland, to determine which of the minimal surfaces the structures resembled.

The team determined that, of the approximately 200 zeolites created to date, only 15 can be used as a template to make schwarzites, and only three of them have been used to date to produce schwarzite ZTCs. Over a million zeolite structures have been predicted, however, so there could be many more possible schwarzite carbon structures made using the zeolite-templating method.

Other co-authors of the paper are Yongjin Lee, Seyed Mohamad Moosavi and Barthel of the École Polytechnique Fédérale de Lausanne, Rocio Mercado of UC Berkeley, Igor Baburin of the Technische Universität Dresden in Germany and Davide Proserpio of the Università degli Studi di Milano in Italy and Samara State Technical University in Russia.

Here’s a link to and a citation for the paper,

Generating carbon schwarzites via zeolite-templating by Efrem Braun, Yongjin Lee, Seyed Mohamad Moosavi, Senja Barthel, Rocio Mercado, Igor A. Baburin, Davide M. Proserpio, and Berend Smit. PNAS August 14, 2018. 201805062; published ahead of print August 14, 2018. https://doi.org/10.1073/pnas.1805062115

This paper appears to be open access.

Bristly hybrid materials

Caption: [Image 1] A carbon fiber covered with a spiky forest of NiCoHC nanowires. Credit: All images reproduced from reference 1 under a Creative Commons Attribution 4.0 International License© 2018 KAUST

It makes me think of small, cuddly things like cats and dogs but it’s not. From an August 7, 2018 King Abdullah University of Science and Technology (KAUST; Saudi Arabia) news release (also published on August 12, 2018 on EurekAlert),

By combining multiple nanomaterials into a single structure, scientists can create hybrid materials that incorporate the best properties of each component and outperform any single substance. A controlled method for making triple-layered hollow nanostructures has now been developed at KAUST. The hybrid structures consist of a conductive organic core sandwiched between layers of electrocatalytically active metals: their potential uses range from better battery electrodes to renewable fuel production.

Although several methods exist to create two-layer materials, making three-layered structures has proven much more difficult, says Peng Wang from the Water Desalination and Reuse Center who co-led the current research with Professor Yu Han, member of the Advanced Membranes and Porous Materials Center at KAUST. The researchers developed a new, dual-template approach, explains Sifei Zhuo, a postdoctoral member of Wang’s team.

The researchers grew their hybrid nanomaterial directly on carbon paper–a mat of electrically conductive carbon fibers. They first produced a bristling forest of nickel cobalt hydroxyl carbonate (NiCoHC) nanowires onto the surface of each carbon fiber (image 1). Each tiny inorganic bristle was coated with an organic layer called hydrogen substituted graphdiyne (HsGDY) (image 2 [not included here]).

Next was the key dual-template step. When the team added a chemical mixture that reacts with the inner NiCoHC, the HsGDY acted as a partial barrier. Some nickel and cobalt ions from the inner layer diffused outward, where they reacted with thiomolybdate from the surrounding solution to form the outer nickel-, cobalt-co-doped MoS2 (Ni,Co-MoS2) layer. Meanwhile, some sulfur ions from the added chemicals diffused inwards to react with the remaining nickel and cobalt. The resulting substance (image 3 [not included here]) had the structure Co9S8, Ni3S2@HsGDY@Ni,Co-MoS2, in which the conductive organic HsGDY layer is sandwiched between two inorganic layers (image 4 [not included here]).

The triple layer material showed good performance at electrocatalytically breaking up water molecules to generate hydrogen, a potential renewable fuel. The researchers also created other triple-layer materials using the dual-template approach

“These triple-layered nanostructures hold great potential in energy conversion and storage,” says Zhuo. “We believe it could be extended to serve as a promising electrode in many electrochemical applications, such as in supercapacitors and sodium-/lithium-ion batteries, and for use in water desalination.”

Here’s a link to and a citation for the paper,

Dual-template engineering of triple-layered nanoarray electrode of metal chalcogenides sandwiched with hydrogen-substituted graphdiyne by Sifei Zhuo, Yusuf Shi, Lingmei Liu, Renyuan Li, Le Shi, Dalaver H. Anjum, Yu Han, & Peng Wang. Nature Communicationsvolume 9, Article number: 3132 (2018) DOI: https://doi.org/10.1038/s41467-018-05474-0 Published 07 August 2018

This paper is open access.

 

Wooden supercapacitors: a cellulose nanofibril story

A May 24, 2018 news item on Nanowerk announces a technique for making sustainable electrodes (Note: A link has been removed),

Carbon aerogels are ultralight, conductive materials, which are extensively investigated for applications in supercapacitor electrodes in electrical cars and cell phones. Chinese scientists have now found a way to make these electrodes sustainably. The aerogels can be obtained directly from cellulose nanofibrils, the abundant cell-wall material in wood, finds the study reported in the journal Angewandte Chemie (“Wood-Derived Ultrathin Carbon Nanofiber Aerogels”).

A May 24, 2018 Wiley Publications press release, which originated the news item, explains further,

Supercapacitors are capacitors that can take up and release a very large amount of energy in a very short time. Key requirements for supercapacitor electrodes are a large surface area and conductivity, combined with a simple production method. Another growing issue in supercapacitor production–mainly for smartphone and electric car technologies–is sustainability. However, sustainable and economical production of carbon aerogels as supercapacitor electrode materials is possible, propose Shu-Hong Yu and colleagues from the University of Science and Technology of China, Hefei, China.

Carbon aerogels are ultralight conductive materials with a very large surface area. They can be prepared by two production routes: the first and cheapest starts from mostly phenolic components and produces aerogels with improvable conductivity, while the second route is based on graphene- and carbon-nanotube precursors. The latter method delivers high-performance aerogels but is expensive and non-environmentally friendly. In their search for different precursors, Yu and colleagues have found an abundant, far less expensive, and sustainable source: wood pulp.

Well, not really wood pulp, but its major ingredient, nanocellulose. Plant cell walls are stabilized by fibrous nanocellulose, and this extractable material has very recently stimulated substantial research and technological development. It forms a highly porous, but very stable transparent network, and, with the help of a recent technique–oxidation with a radical scavenger called TEMPO–it forms a microporous hydrogel of highly oriented cellulose nanofibrils with a uniform width and length. As organic aerogels are produced from hydrogels by drying and pyrolysis, the authors attempted pyrolysis of supercritically or freeze-dried nanofibrillated cellulose hydrogel.

As it turns out, the method was not as straightforward as expected because ice crystal formation and insufficient dehydration hampered carbonization, according to the authors. Here, a trick helped. The scientists pyrolyzed the dried gel in the presence of the organic acid catalyst para-toluenesulfonic acid. The catalyst lowered the decomposition temperature and yielded a “mechanically stable and porous three-dimensional nanofibrous network” featuring a “large specific surface area and high electrical conductivity,” the authors reported.

The authors also demonstrated that their wood-derived carbon aerogel worked well as a binder-free electrode for supercapacitor applications. The material displayed electrochemical properties comparable to commercial electrodes. The method is an interesting and innovative way in which to fabricate sustainable materials suitable for use in high-performance electronic devices.

This is the first time I’ve seen work on wood-based nanocellulose from China. Cellulose according to its Wikipedia entry is: ” … the most abundant organic polymer on Earth.” For example, there’s more cellulose in cotton than there is wood. So, I find it interesting that in a country not known for its forests, nanocellulose (in this project anyway) is being derived from wood.

Here’s a link to and a citation for the paper,

Wood‐Derived Ultrathin Carbon Nanofiber Aerogels by Si‐Cheng Li, Bi‐Cheng Hu, Dr. Yan‐Wei Ding, Prof. Hai‐Wei Liang, Chao Li, Dr. Zi‐You Yu, Dr. Zhen‐Yu Wu, Prof. Wen‐Shuai Chen, Prof. Shu‐Hong Yu. Angewandt Chemie First published: 23 April 2018 DOI: https://doi.org/10.1002/anie.201802753

This paper is behind a paywall.

Mixing the unmixable for all new nanoparticles

This news comes out of the University of Maryland and the discovery could led to nanoparticles that have never before been imagined. From a March 29, 2018 news item on ScienceDaily,

Making a giant leap in the ‘tiny’ field of nanoscience, a multi-institutional team of researchers is the first to create nanoscale particles composed of up to eight distinct elements generally known to be immiscible, or incapable of being mixed or blended together. The blending of multiple, unmixable elements into a unified, homogenous nanostructure, called a high entropy alloy nanoparticle, greatly expands the landscape of nanomaterials — and what we can do with them.

This research makes a significant advance on previous efforts that have typically produced nanoparticles limited to only three different elements and to structures that do not mix evenly. Essentially, it is extremely difficult to squeeze and blend different elements into individual particles at the nanoscale. The team, which includes lead researchers at University of Maryland, College Park (UMD)’s A. James Clark School of Engineering, published a peer-reviewed paper based on the research featured on the March 30 [2018] cover of Science.

A March 29, 2018 University of Maryland press release (also on EurekAlert), which originated the news item, delves further (Note: Links have been removed),

“Imagine the elements that combine to make nanoparticles as Lego building blocks. If you have only one to three colors and sizes, then you are limited by what combinations you can use and what structures you can assemble,” explains Liangbing Hu, associate professor of materials science and engineering at UMD and one of the corresponding authors of the paper. “What our team has done is essentially enlarged the toy chest in nanoparticle synthesis; now, we are able to build nanomaterials with nearly all metallic and semiconductor elements.”

The researchers say this advance in nanoscience opens vast opportunities for a wide range of applications that includes catalysis (the acceleration of a chemical reaction by a catalyst), energy storage (batteries or supercapacitors), and bio/plasmonic imaging, among others.

To create the high entropy alloy nanoparticles, the researchers employed a two-step method of flash heating followed by flash cooling. Metallic elements such as platinum, nickel, iron, cobalt, gold, copper, and others were exposed to a rapid thermal shock of approximately 3,000 degrees Fahrenheit, or about half the temperature of the sun, for 0.055 seconds. The extremely high temperature resulted in uniform mixtures of the multiple elements. The subsequent rapid cooling (more than 100,000 degrees Fahrenheit per second) stabilized the newly mixed elements into the uniform nanomaterial.

“Our method is simple, but one that nobody else has applied to the creation of nanoparticles. By using a physical science approach, rather than a traditional chemistry approach, we have achieved something unprecedented,” says Yonggang Yao, a Ph.D. student at UMD and one of the lead authors of the paper.

To demonstrate one potential use of the nanoparticles, the research team used them as advanced catalysts for ammonia oxidation, which is a key step in the production of nitric acid (a liquid acid that is used in the production of ammonium nitrate for fertilizers, making plastics, and in the manufacturing of dyes). They were able to achieve 100 percent oxidation of ammonia and 99 percent selectivity toward desired products with the high entropy alloy nanoparticles, proving their ability as highly efficient catalysts.

Yao says another potential use of the nanoparticles as catalysts could be the generation of chemicals or fuels from carbon dioxide.

“The potential applications for high entropy alloy nanoparticles are not limited to the field of catalysis. With cross-discipline curiosity, the demonstrated applications of these particles will become even more widespread,” says Steven D. Lacey, a Ph.D. student at UMD and also one of the lead authors of the paper.

This research was performed through a multi-institutional collaboration of Prof. Liangbing Hu’s group at the University of Maryland, College Park; Prof. Reza Shahbazian-Yassar’s group at University of Illinois at Chicago; Prof. Ju Li’s group at the Massachusetts Institute of Technology; Prof. Chao Wang’s group at Johns Hopkins University; and Prof. Michael Zachariah’s group at the University of Maryland, College Park.

What outside experts are saying about this research:

“This is quite amazing; Dr. Hu creatively came up with this powerful technique, carbo-thermal shock synthesis, to produce high entropy alloys of up to eight different elements in a single nanoparticle. This is indeed unthinkable for bulk materials synthesis. This is yet another beautiful example of nanoscience!,” says Peidong Yang, the S.K. and Angela Chan Distinguished Professor of Energy and professor of chemistry at the University of California, Berkeley and member of the American Academy of Arts and Sciences.

“This discovery opens many new directions. There are simulation opportunities to understand the electronic structure of the various compositions and phases that are important for the next generation of catalyst design. Also, finding correlations among synthesis routes, composition, and phase structure and performance enables a paradigm shift toward guided synthesis,” says George Crabtree, Argonne Distinguished Fellow and director of the Joint Center for Energy Storage Research at Argonne National Laboratory.

More from the research coauthors:

“Understanding the atomic order and crystalline structure in these multi-element nanoparticles reveals how the synthesis can be tuned to optimize their performance. It would be quite interesting to further explore the underlying atomistic mechanisms of the nucleation and growth of high entropy alloy nanoparticle,” says Reza Shahbazian-Yassar, associate professor at the University of Illinois at Chicago and a corresponding author of the paper.

“Carbon metabolism drives ‘living’ metal catalysts that frequently move around, split, or merge, resulting in a nanoparticle size distribution that’s far from the ordinary, and highly tunable,” says Ju Li, professor at the Massachusetts Institute of Technology and a corresponding author of the paper.

“This method enables new combinations of metals that do not exist in nature and do not otherwise go together. It enables robust tuning of the composition of catalytic materials to optimize the activity, selectivity, and stability, and the application will be very broad in energy conversions and chemical transformations,” says Chao Wang, assistant professor of chemical and biomolecular engineering at Johns Hopkins University and one of the study’s authors.

Here’s a link to and a citation for the paper,

Carbothermal shock synthesis of high-entropy-alloy nanoparticles by Yonggang Yao, Zhennan Huang, Pengfei Xie, Steven D. Lacey, Rohit Jiji Jacob, Hua Xie, Fengjuan Chen, Anmin Nie, Tiancheng Pu, Miles Rehwoldt, Daiwei Yu, Michael R. Zachariah, Chao Wang, Reza Shahbazian-Yassar, Ju Li, Liangbing Hu. Science 30 Mar 2018: Vol. 359, Issue 6383, pp. 1489-1494 DOI: 10.1126/science.aan5412

This paper is behind a paywall.