Tag Archives: fullerenes

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.

Interstellar fullerenes

This work from Russia on fullerenes (also known as buckministerfullerenes, C60, and/or buckyballs) is quite interesting and dates back more than a year. I’m not sure why the work is being publicized now but nanotechnology and interstellar space is not covered here often enough so, here goes, (from a January 29, 2018 Kazan Federal University press release (also on EurekAlert), Note: Links have been removed,

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

C60+ – looking for the bucky-ball in interstellar space by G. A. Galazutdinov, V. V. Shimansky, A. Bondar, G. Valyavin, J. Krełowski. Monthly Notices of the Royal Astronomical Society, Volume 465, Issue 4, 11 March 2017, Pages 3956–3964, https://doi.org/10.1093/mnras/stw2948 Published: 22 December 2016

This paper is behind a paywall.

h/t January 29, 2018 news item on Nanowerk

OECD (Organization for Economic Cooperation and Development) Dossiers on Nanomaterials Are of “Little to No Value for assessing risk?”

The announcement that a significant portion of the OECD’s (Organization for Economic Cooperation and Development) dossiers on 11 nanomaterials have next to no value for assessing risk seems a harsh judgment from the Center for International Environmental Law (CIEL). From a March 1, 2017 posting by Lynn L. Bergeson on the Nanotechnology Now,

On February 23, 2017, the Center for International Environmental Law (CIEL) issued a press release announcing a new report, commissioned by CIEL, the European Environmental Citizens’ Organization for Standardization (ECOS), and the Oeko-Institute, that “shows that most of the information made available by the Sponsorship Testing Programme of the Organisation for Economic Co-operation and Development (OECD) is of little to no value for the regulatory risk assessment of nanomaterials.”

Here’s more from the Feb. 23, 3017 CIEL press release, which originated the posting,

The study published today [Feb. 23, 2017] was delivered by the Institute of Occupational Medicine (IOM) based in Singapore. IOM screened the 11,500 pages of raw data of the OECD dossiers on 11 nanomaterials, and analysed all characterisation and toxicity data on three specific nanomaterials – fullerenes, single-walled carbon nanotubes, and zinc oxide.

“EU policy makers and industry are using the existence of the data to dispel concerns about the potential health and environmental risks of manufactured nanomaterials,” said David Azoulay, Senior Attorney for CIEL. “When you analyse the data, in most cases, it is impossible to assess what material was actually tested. The fact that data exists about a nanomaterial does not mean that the information is reliable to assess the hazards or risks of the material.”

The dossiers were published in 2015 by the OECD’s Working Party on Manufactured Nanomaterials (WPMN), which has yet to draw conclusions on the data quality. Despite this missing analysis, some stakeholders participating in EU policy-making – notably the European Chemicals Agency (ECHA) and the European Commission’s Joint Research Centre – have presented the dossiers as containing information on nano-specific human health and environmental impacts. Industry federations and individual companies have taken this a step further emphasizing that there is enough information available to discard most concerns about potential health or environmental risks of manufactured nanomaterials.

“Our study shows these claims that there is sufficient data available on nanomaterials are not only false, but dangerously so,” said Doreen Fedrigo, Senior Policy Officer of ECOS. ”The lack of nano-specific information in the dossiers means that the results of the tests cannot be used as evidence of no ‘nano-effect’ of the tested material. This information is crucial for regulators and producers who need to know the hazard profile of these materials. Analysing the dossiers has shown that legislation detailing nano-specific information requirements is crucial for the regulatory risk assessment of nanomaterials.”

The report provides important recommendations on future steps in the governance of nanomaterials. “Based on our analysis, serious gaps in current dossiers must be filled in with characterisation information, preparation protocols, and exposure data,” said Andreas Hermann of the Oeko-Institute. “Using these dossiers as they are and ignoring these recommendations would mean making decisions on the safety of nanomaterials based on faulty and incomplete data. Our health and environment requires more from producers and regulators.”

CIEL has an Analysis of OECD WPMN Dossiers Regarding the Availability of Data to Evaluate and Regulate Risk (Dec 2016) webpage which provides more information about the dossiers and about the research into the dossiers and includes links to the report, the executive summer, and the dataset,

The Sponsorship Testing Programme of the Working Party on Manufactured Nanomaterials (WPMN) of the Organisation for Economic Co-operation and Development (OECD) started in 2007 with the aim to test a selection of 13 representative nanomaterials for many endpoints. The main objectives of the programme were to better understand what information on intrinsic properties of the nanomaterials might be relevant for exposure and hazards assessment and assess the validity of OECD chemicals Test Guidelines for nanomaterials. The testing programme concluded in 2015 with the publication of dossiers on 11 nanomaterials: 11,500 pages of raw data to be analysed and interpreted.

The WPMN has not drawn conclusions on the data quality, but some stakeholders participating in EU policy-making – notably the European Chemicals Agency and the European Commission’s Joint Research Centre – presented the dossiers as containing much scientific information that provided a better understanding of their nano-specific human health and environmental impacts. Industry federations and individual companies echoed the views, highlighting that there was enough information available to discard most concerns about potential health or environmental risks of manufactured nanomaterials.

As for the OECD, it concluded, even before the publication of the dossiers, that “many of the existing guidelines are also suitable for the safety assessment of nanomaterials” and “the outcomes (of the sponsorship programme) will provide useful information on the ‘intrinsic properties’ of nanomaterials.”

The Center for International Environmental Law (CIEL), the European Citizens’ Organisation for Standardisation (ECOS) and the Öko-Institut commissioned scientific analysis of these dossiers to assess the relevance of the data for regulatory risk assessment.

The resulting report: Analysis of OECD WPMN dossiers regarding the availability of data to evaluate and regulate risk, provides insights illustratating how most of the information made available by the sponsorship programme is of little to no value in identifying hazards or in assessing risks due to nanomaterials.

The analysis shows that:

  • Most studies and documents in the dossiers contain insufficient characterisation data about the specific nanomaterial addressed (size, particle distribution, surface shape, etc.), making it impossible to assess what material was actually tested.
  • This makes it impossible to make any firm statements regarding the nano-specificity of the hazard data published, or the relationship between observed effects and specific nano-scale properties.
  • Less than 2% of the study records provide detail on the size of the nanomaterial tested. Most studies use mass rather than number or size distribution (so not following scientifically recommended reporting practice).
  • The absence of details on the method used to prepare the nanomaterial makes it virtually impossible to correlate an identified hazard with specific nanomaterial characteristic. Since the studies do not indicate dispersion protocols used, it is impossible to assess whether the final dispersion contained the intended mass concentration (or even the actual presence of nanomaterials in the test system), how much agglomeration may have occurred, and how the preparation protocols may have influenced the size distribution.
  • There is not enough nano-specific information in the dossiers to inform about nano-characteristics of the raw material that influence their toxicology. This information is important for regulators and its absence makes information in the dossier irrelevant to develop read-across guidelines.
  • Only about half of the endpoint study records using OECD Test Guideliness (TGs) were delivered using unaltered OECD TGs, thereby respecting the Guidelines’ requirements. The reasons for modifications of the TGs used in the tests are not clear from the documentation. This includes whether the study record was modified to account for challenges related to specific nanomaterial properties or for other, non-nano-specific reasons.
  • The studies do not contain systematic testing of the influence of nano-specific characteristics on the study outcome, and they do not provide the data needed to assess the effect of nano-scale features on the Test Guidelines. Given the absence of fundamental information on nanomaterial characteristics, the dossiers do not provide evidence of the applicability of existing OECD Test Guidelines to nanomaterials.

The analysis therefore dispels several myths created by some stakeholders following publication of the dossiers and provides important perspective for the governance of nanomaterials. In particular, the analysis makes recommendations to:

  • Systematically assess the validity of existing Test Guidelines for relevance to nanomaterials
  • Develop Test Guidelines for dispersion and other test preparations
  • Define the minimum characteristics of nanomaterials that need to be reported
  • Support the build-up of exposure database
  • Fill the gaps in current dossiers with characterisation information, preparation protocols and exposure data

Read full report.
Read executive summary.
Download full dataset.

This is not my area of expertise and while I find the language a bit inflammatory, it’s my understanding that there are great gaps in our understanding of nanomaterials and testing for risk assessment has been criticized for many of the reasons pointed out by CIEL, ECOS, and the Oeko-Institute.

You can find out more about CIEL here; ECOS here; and the Oeko-Institute (also known as Öko-Institute) here.

The birth of carbon nanotubes (CNTs): a history

There is a comprehensive history of the carbon nanotube stretching back to prehistory and forward to recent times in a June 3, 2016 Nanowerk Spotlight article by C.K. Nisha and Yashwant Mahajan of the Center of Knowledge Management of Nanoscience & Technology (CKMNT) in India. The authors provide an introduction explaining the importance of CNTs,

Carbon nanotubes (CNTs) have been acknowledged as the material of the 21st century. They possess unique combination of extraordinary mechanical, electronic, transport, electrical and optical, properties and nanoscale sizes making them suitable for a variety of applications ranging from engineering, electronics, optoelectronics, photonics, space, defence industry, medicine, molecular and biological systems and so on and so forth. Worldwide demand for CNTs is increasing at a rapid pace as applications for the material are being matured.

According to MarketsandMarkets (M&M), the global market for carbon nanotubes in 2015 was worth about $2.26 billion1; an increase of 45% from 2009 (i.e. ~ $ 1.24 billion). This was due to the growing potential of CNTs in electronics, plastics and energy storage applications and the projected market of CNTs is expected to be around $ 5.64 billion in 2020.

In view of the scientific and technological potential of CNTs, it is of immense importance to know who should be credited for their discovery. In the present article, we have made an attempt to give a glimpse into the discovery and early history of this fascinating material for our readers. Thousands of papers are being published every year on CNTs or related areas and most of these papers give credit for the discovery of CNTs to Sumio Iijima of NEC Corporation, Japan, who, in 1991, published a ground-breaking paper in Nature reporting the discovery of multi-walled carbon nanotubes (MWCNTs)2. This paper has been cited over 27,105 times in the literature (as on January 12, 2016, based on Scopus database). This discovery by Iijima has triggered an avalanche of scientific publications and catapulted CNTs onto the global scientific stage.

Nisha and Mahajan then prepare to take us back in time,

In a guest editorial for the journal Carbon, Marc Monthioux and Vladimir L. Kuznetsov3 have tried to clear the air by describing the chronological events that led to the discovery of carbon nanotubes. As one delves deeper into the history of carbon nanotubes, it becomes more apparent that the origin of CNTs could be even pre-historic in nature.

Recently, Ponomarchuk et al from Russia have reported the presence micro and nano carbon tubes in igneous rocks formed about 250 million years ago4-7. They suggested the possibility of formation of carbon nanotubes during the magmatic processes. It is presumed that the migration of hydrocarbon fluids through the residual melt of the rock groundmass created gas-saturated areas (mostly CH4, CO2, CO) in which condensation and decomposition of hydrocarbon in presence of metal elements resulted in the formation of micro and sub-micron carbon tubes.

Another most compelling evidence of pre-historic naturally occurring carbon nanotubes (MWCNTs) is based on the TEM studies carried out by Esquivel and Murr8 that analyzed 10,000-year-old Greenland ice core samples and it was suggested that probably they could have been formed during combustion of natural gas/methane during natural processes.

However, the validity of this evidence is questionable owing to the lack of clear high-resolution TEM images, high-quality diffraction patterns or Raman spectroscopy data. In addition, [an]other interesting possibility is that the carbon nanotubes could have been directly formed by the transformation of naturally occurring C60 fullerenes in nature without the assistance of man, given the right conditions prevail. Suchanek et al.,9 have actually demonstrated this thesis, under the laboratory environment, by transforming C60 fullerenes into CNTs under hydrothermal conditions.

There is a large body of evidence in literature about the existence of naturally occurring fullerenes in nature, e.g., coal, carboneous rocks, interstellar media, etc. Since the above experiments were conducted under the simulated geological environment, their results imply that CNTs may form in natural hydrothermal environment.

This hypothesis was further corroborated by Velasco-Santos and co-workers10, when they reported the presence of CNTs in a coal–petroleum mix obtained from an actual oil well, identified by the PEMEX (the Mexican Petroleum Company) as P1, which is located in Mexico’s southeast shore. TEM studies revealed that the coal-petroleum mix contained predominantly end-capped CNTs that are nearly 2 µm long with outer diameter varying between few to several tenths of nanometers.

There’s another study supporting the notion that carbon nanotubes may be formed naturally,

In yet another study, researchers from Germany11 have synthesized carbon nanotubes using igneous rock from Mount Etna lava as both support and catalyst. The naturally occurring iron oxide particles present in Etna lava rock make it an ideal material for growing and immobilizing nanocarbons.

When a mixture of ethylene and hydrogen were passed over the pulverized rocks reduced in a hydrogen atmosphere at 700°C, the iron particles catalyzed the decomposition of ethylene to elemental carbon, which gets deposited on the lava rock in the form of tiny tubes and fibers.
This study showed that if a carbon source is available, CNTs/CNFs can grow on a mineral at moderate temperatures, which directs towards the possibilities of carbon nanotube formation in active suboceanic volcanos or even in interstellar space where methane, atomic hydrogen, carbon oxides, and metallic iron are present.

This fascinating and informative piece was originally published in the January 2016 edition of Nanotech Insights (CKMNT newsletter; scroll down) and can be found there although it may be more easily accessible as the June 3, 2016 Nanowerk Spotlight article where it extends over five (Nanowerk) pages and has a number of embedded images along with an extensive list of references at the end.

Enjoy!

Unraveling carbyne (one-dimensional carbon)

An international group of researchers has developed a technique for producing a record-breaking length of one-dimensional carbon (carbon chain) according to an April 4, 2016 news item on Nanowerk,

Elemental carbon appears in many different modifications, including diamond, fullerenes and graphene. Their unique structural, electronic, mechanical, transport and optical properties have a broad range of applications in physics, chemistry and materials science, including composite materials, nanoscale light emitting devices and energy harvesting materials. Within the “carbon family”, only carbyne, the truly one-dimensional form of carbon, has not yet been synthesized despite having been studied for more than 50 years. Its extreme instability in ambient conditions rendered the final experimental proof of its existence elusive.

An international collaboration of researchers now succeeded in developing a novel route for the bulk production of carbon chains composed of more than 6,400 carbon atoms by using thin double-walled carbon nanotubes as protective hosts for the chains.

An April 4, 2016 University of Vienna press release (also on EurekAlert) provides another perspective on the research,

Even in its elemental form, the high bond versatility of carbon allows for many different well-known materials, including diamond and graphite. A single layer of graphite, termed graphene, can then be rolled or folded into carbon nanotubes or fullerenes, respectively. To date, Nobel prizes have been awarded for both graphene (2010) and fullerenes (1996). Although the existence of carbyne, an infinitely long carbon chain, was proposed in 1885 by Adolf von Baeyer (Nobel laureate for his overall contributions in organic chemistry, 1905), scientists have not yet been able to synthesize this material. Von Baeyer even suggested that carbyne would remain elusive as its high reactivity would always lead to its immediate destruction. Nevertheless, carbon chains of increasing length have been successfully synthesized over the last 50 years, with a record of around 100 carbon atoms (2003). This record has now been broken by more than one order of magnitude, with the demonstration of micrometer length-scale chains.

The new record

Researchers from the University of Vienna, led by Thomas Pichler, have presented a novel approach to grow and stabilize carbon chains with a record length of 6,000 carbon atoms, improving the previous record by more than one order of magnitude. They use the confined space inside a double-walled carbon nanotube as a nano-reactor to grow ultra-long carbon chains on a bulk scale. In collaboration with the groups of Kazu Suenaga at the AIST Tsukuba [National Institute of Advanced Industrial Science and Technology] in Japan, Lukas Novotny at the ETH Zürich [Swiss Federal Institute of Technology] in Switzerland and Angel Rubio at the MPI [Max Planck Institute] Hamburg in Germany and UPV/EHU [University of the Basque Country] San Sebastian in Spain, the existence of the chains has been unambiguously confirmed by using a multitude of sophisticated, complementary methods. These are temperature dependent near- and far-field Raman spectroscopy with different lasers (for the investigation of electronic and vibrational properties), high resolution transmission electron spectroscopy (for the direct observation of carbyne inside the carbon nanotubes) and x-ray scattering (for the confirmation of bulk chain growth).

The researchers present their study in the latest edition of Nature Materials. “The direct experimental proof of confined ultra-long linear carbon chains, which are more than an order of magnitude longer than the longest proven chains so far, can be seen as a promising step towards the final goal of unraveling the “holy grail” of carbon allotropes, carbyne”, explains the lead author, Lei Shi.

Application potential

Carbyne is very stable inside double-walled carbon nanotubes. This property is crucial for its eventual application in future materials and devices. According to theoretical models, carbyne’s mechanical properties exceed all known materials, outperforming both graphene and diamond. Carbyne’s electrical properties suggest novel nanoelectronic applications in quantum spin transport and magnetic semiconductors.

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

Confined linear carbon chains as a route to bulk carbyne by Lei Shi, Philip Rohringer, Kazu Suenaga, Yoshiko Niimi, Jani Kotakoski, Jannik C. Meyer, Herwig Peterlik, Marius Wanko, Seymur Cahangirov, Angel Rubio, Zachary J. Lapin, Lukas Novotny, Paola Ayala, & Thomas Pichler. Nature Materials (2016) doi:10.1038/nmat4617 Published online 04 April 2016

This paper is behind a paywall.

But, there is this earlier and open access version on arXiv.org,

Confined linear carbon chains: A route to bulk carbyne
Lei Shi, Philip Rohringer, Kazu Suenaga, Yoshiko Niimi, Jani Kotakoski, Jannik C. Meyer, Herwig Peterlik, Paola Ayala, Thomas Pichler (Submitted on 17 Jul 2015 (v1), last revised 20 Jul 2015 (this version, v2))

Soccer balls with no resistance (superconductivity)

Known as a fullerene (also buckminsterfullerene, buckyballs, and/or C60), the soccer ball in question is helping scientists to better understand how to develop materials that are superconductive at room temperature. A Feb. 9, 2016 news item on Nanotechnology Now describes the latest in ‘soccer ball’ research,

Superconductors have long been confined to niche applications, due to the fact that the highest temperature at which even the best of these materials becomes resistance-free is minus 70 degrees Celsius. Nowadays they are mainly used in magnets for nuclear magnetic resonance tomographs, fusion devices and particle accelerators. Physicists from the Max Planck Institute for the Structure and Dynamics of Matter at the Center for Free-Electron Laser Science (CFEL) in Hamburg shone laser pulses at a material made up from potassium atoms and carbon atoms arranged in bucky ball structures. For a small fraction of a second, they found it to become superconducting at more than 100 degrees Kelvin – around minus 170 degrees Celsius. A similar effect was already discovered in 2013 by scientists of the same group in a different material, a ceramic oxide belonging to the family of so-called “cuprates”. As fullerenes have a relatively simple chemical structure, the researchers hope to be able to gain a better understanding of the phenomenon of light-induced superconductivity at high temperatures through their new experiments. Such insights could help in the development of a material which conducts electricity at room temperature without losses, and without optical excitation.

A Feb. 8, 2016 Max Planck Institute press release (also on EurekAlert but dated Feb. 9, 2016), which originated the news item, expands on the theme of superconductivity at room temperature,

Andrea Cavalleri, Director at the Max Planck Institute for the Structure and Dynamics of Matter, and his colleagues aim at paving the way for the development of materials that lose their electrical resistance at room temperature. Their observation that fullerenes, when excited with laser pulses, can become superconductive at minus 170 degrees Celsius, takes them a step closer to achieving this goal. This discovery could contribute to establishing a more comprehensive understanding of light-induced superconductivity, because it is easier to formulate a theoretical explanation for fullerenes than for cuprates. A complete explanation of this effect could, in turn, help the scientists to gain a better understanding of the phenomenon of high-temperature superconductivity and provide a recipe for an artificial superconductor that conducts electricity without resistance losses at room temperature.

In 2013, researchers from Cavalleri’s group demostrated that under certain conditions it may be possible for a material to conduct electricity at room temperature without resistance loss. A ceramic oxide belonging to the family of cuprates was shown to become superconductive without any cooling for a few trillionths of a second when the scientists excited it using an infrared laser pulse. One year later, the Hamburg-based scientists presented a possible explanation for this effect.

They observed that, following excitation with the flash of light, the atoms in the crystal lattice change position. This shift in position persists as does the superconducting state of the material. Broadly speaking, the light-induced change in the structure clears the way for the electrons so that they can move through the ceramic without losses. However, the explanation is very dependent on the highly specific crystalline structure of cuprates. As the process was understood at the time, it could have involved a phenomenon that only arises in this kind of materials.

The researchers have included in the press release an image illustrating the latest work being described in the press release excerpt which follows this,

Intense laser flashes remove the electrical resistance of a crystal layer of the alkali fulleride K3C60, a football-like molecule containing 60 carbon atoms. This is observed at temperatures at least as high as minus 170 degrees Celsius. © J.M. Harms/MPI for the Structure and Dynamics of Matter

Intense laser flashes remove the electrical resistance of a crystal layer of the alkali fulleride K3C60, a football-like molecule containing 60 carbon atoms. This is observed at temperatures at least as high as minus 170 degrees Celsius.
© J.M. Harms/MPI for the Structure and Dynamics of Matter

The press release goes on to provide some technical details about the most recent research,

The team headed by Cavalleri therefore asked themselves whether light could also break the electrical resistance of more traditional superconductors, the physics of which is better understood. The researchers from the Max Planck Institute for the Structure and Dynamics of Matter, among which Daniele Nicoletti and Matteo Mitrano, have now hit the jackpot using a substance that is very different to cuprates: the fulleride K3C60, a metal composed of so-called Buckminster fullerenes. These hollow molecules consist of 60 carbon atoms which bond in the shape of a football: a sphere comprising pentagons and hexagons. With the help of intercalated positively charged potassium ions, which work like a kind of cement, the negatively charged fullerenes stick to each other to form a solid. This so-called alkali fulleride is a metal which becomes superconductive below a critical temperature of around minus 250 degrees Celsius.

The researchers then irradiated the alkali fulleride with infrared light pulses of just a few billionths of a microsecond and repeated their experiment for a range of temperatures between the critical temperature and room temperature. They set the frequency of the light source so that it excited the fullerenes to produce vibrations. This causes the carbon atoms to oscillate in such a way that the pentagons in the football expand and contract. It was hoped that this change in the structure could generate transient superconductivity at high temperatures in a similar way to the process in cuprates.

To test this, the scientists irradiated the sample with a second light pulse at the same time as the infrared pulse, albeit at a frequency in the terahertz range. The strength at which this pulse is reflected indicates the conductivity of the material to the researchers, meaning how easily electrons move through the alkali fulleride. The result here was an extremely high conductivity. “We are pretty confident that we have induced superconductivity at temperatures at least as high as minus 170 degrees Celsius,” says Daniele Nicoletti. This means that the experiment in Hamburg presents one of the highest ever-observed critical temperatures outside of the material class of cuprates.

“We are now planning to carry out other experiments which should enable us to reach a more detailed understanding of the processes at work here,” says Nicoletti. What they would like to do next is analyze the crystal structure during excitation with the infrared light. As was previously the case with the cuprate, this should help to explain the phenomenon. The researchers would then like to irradiate the material with light pulses that last much longer. “Although this is technically very complicated, it could extend the lifetime of superconductivity, making it potentially relevant for applications,” concludes Nicoletti.

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

Possible light-induced superconductivity in K3C60 at high temperature by M. Mitrano, A. Cantaluppi, D. Nicoletti, S. Kaiser, A. Perucchi, S. Lupi, P. Di Pietro, D. Pontiroli, M. Riccò, S. R. Clark, D. Jaksch, & A. Cavalleri. Nature (2016) doi:10.1038/nature16522 Published online 08 February 2016

This paper is behind a paywall.

University of New Brunswick (Canada), ‘sun in a can’, and buckyballs

Cutting the cost for making solar cells could be a step in the right direction for more widespread adoption. At any rate, that seems to be the motivation for Dr. Felipe Chibante of the University of New Brunswick  and his team as they’ve worked for the past three years or so on cutting production costs for fullerenes (also known as, buckminsterfullerenes, C60, and buckyballs). From a Dec. 23, 2015 article by Michael Tutton for Canadian Press,

A heating system so powerful it gave its creator a sunburn from three metres away is being developed by a New Brunswick engineering professor as a method to sharply reduce the costs of making the carbon used in some solar cells.

Felipe Chibante says his “sun in a can” method of warming carbon at more than 5,000 degrees Celsius helps create the stable carbon 60 needed in more flexible forms of photovoltaic panels.

Tutton includes some technical explanations in his article,

Chibante and senior students at the University of New Brunswick created the system to heat baseball-sized lumps of plasma — a form of matter composed of positively charged gas particles and free-floating negatively charged electrons — at his home and later in a campus lab.

According to a May 22, 2012 University of New Brunswick news release received funding of almost $1.5M from the Atlantic Canada Opportunities Agency for his work with fullerenes,

Dr. Felipe Chibante, associate professor in UNB’s department of chemical engineering, and his team at the Applied Nanotechnology Lab received nearly $1.5 million to lower the cost of fullerenes, which is the molecular form of pure carbon and is a critical ingredient for the plastic solar cell market.

Dr. Chibante and the collaborators on the project have developed fundamental synthesis methods that will be integrated in a unique plasma reactor to result in a price reduction of 50-75 per cent.

Dr. Chibante and his work were also featured in a June 10, 2013 news item on CBC (Canadian Broadcasting Corporation) news online,

Judges with the New Brunswick Innovation Fund like the idea and recently awarded Chibante $460,000 to continue his research at the university’s Fredericton campus.

Chibante has a long history of working with fullerenes — carbon molecules that can store the sun’s energy. He was part of the research team that discovered fullerenes in 1985 [the three main researchers at Rice University, Texas, received Nobel Prizes for the work].

He says they can be added to liquid, spread over plastic and shingles and marketed as a cheaper way to convert sunlight into electricity.

“What we’re trying to do in New Brunswick with the science research and innovation is we’re really trying to get the maximum bang for the buck,” said Chibante.

As it stands, fullerenes cost about $15,000 per kilogram. Chibante hopes to lower the cost by a factor of 10.

The foundation investment brings Chibante’s research funding to about $6.2 million.

Not everyone is entirely sold on this approach to encouraging solar energy adoption (from the CBC news item),

The owner of Urban Pioneer, a Fredericton [New Brunswick] company that sells alternative energy products, likes the concept, but doubts there’s much of a market in New Brunswick.

“We have conventional solar panels right now and they’re not that popular,” said Tony Craft.

“So I can’t imagine, like, when you throw something completely brand new into it, I don’t know how people are going to respond to that even, so it may be a very tough sell,” he said.

Getting back to Chibante’s breakthrough (from Tutton’s Dec. 23, 2015 article),

The 52-year-old researcher says he first set up the system to operate in his garage.

He installed optical filters to watch the melting process but said the light from the plasma was so intense that he later noticed a sunburn on his neck.

The plasma is placed inside a container that can contain and cool the extremely hot material without exposing it to the air.

The conversion technology has the advantage of not using solvents and doesn’t produce the carbon dioxide that other baking systems use, says Chibante.

He says the next stage is finding commercial partners who can help his team further develop the system, which was originally designed and patented by French researcher Laurent Fulcheri.

Chibante said he doesn’t believe the carbon-based, thin-film solar cells will displace the silicon-based cells because they capture less energy.

But he nonetheless sees a future for the more flexible sheets of solar cells.

“You can make fibres, you can make photovoltaic threads and you get into wearable, portable forms of power that makes it more ubiquitous rather than having to carry a big, rigid structure,” he said.

The researcher says the agreement earlier this month [Nov. 30 – Dec. 12, 2015] in Paris among 200 countries to begin reducing the use of fossil fuels and slow global warming may help his work.

By the way,  Chibante estimates production costs for fullerenes, when using his system, would be less that $50/kilogram for what is now the highest priced component of carbon-based solar cells.

There is another researcher in Canada who works in the field of solar energy, Dr. Ted Sargent at the University of Toronto (Ontario). He largely focuses on harvesting solar energy by using quantum dots. I last featured Sargent’s quantum dot work in a Dec. 9, 2014 posting.

A trio of nano news items from Japan (Irago Conference 2015, novel tuneable metallofullerenes, and nanoislands and skeletal skin for fuel cells)

Getting onto a list for news releases from Japan has been a boon. I don’t know how it happened but now I can better keep up with the nanotechnology effort in the country where the term was first coined (Norio Taniguchi) and which is a research leader in this field.

Irago Conference

This is a very intriguing conference, from a joint Oct. 18, 2015 Toyohashi University of Technology and University of Electro-Communications press release,

Organized by the Toyohashi University of Technology and University of Electro-Communications, Tokyo, the Irago Conference aims to enhance mutual understanding between scientists, engineers, policy makers, and experts from a wide spectrum of pure and applied sciences in order to resolve major global issues.

The Irago Conference 2015 is a unique conference combining thought provoking insights into global issues including disaster mitigation, neuroscience, public health monitoring, and nanotechnology [emphasis mine] by internationally renowned invited speakers with selected talks, posters, and demonstrations from academics, industrialists, and think tanks. The conference is truly a ‘360 degree outlook on critical scientific and technological challenges’ facing mankind.

Recent changes in global economics and industrial priorities, environmental and energy policies, food production and population movements have produced formidable challenges that must be addressed for sustaining life on earth.

The Irago Conference will highlight the major issues by bringing together experts from across the world who will give their views on key areas such as energy and natural resources, medicine and public health, disaster prevention and management, as well as other advances in science, technology and life sciences.

Observation, measurement, and monitoring are the keywords of the core topics covered at Irago 2015 with invited speakers Professor Masashi Hayakawa (University of Electro-Communications, Japan) presenting his pioneering research on “Earthquake prediction with electromagnetic phenomena, and Nobuhiko Okabe  (Kawasaki City Institute for Public Health, Japan) discussing “The role and contribution of Kawasaki City Institute for Public Health (Local Public Health Laboratory), locally and globally” with first hand examples of monitoring food safety and the spread of possible diseases carried by insects.

The Irago Conference will be streamed live. Visit the conference website for the links to the streaming site.

http://iragoconference.jp/

When: Thursday, 22 October 2015 to Friday 23  October 2015.

Where: Irago Sea-Park & Spa Hotel, Tahara, Aichi, Japan

They don’t appear to have set up the streaming link yet.

Tuneable metallofullerenes

Originally issued as a Sept. 21, 2015 press release, the University of Electro-Communications has issued an Oct. 19, 2015 version,

Tiny nanoscale molecules in the form of spherical carbon cages, or ‘fullerenes’, have received considerable attention in recent years. Individual or small groups of atoms can be trapped inside fullerenes, creating stable molecules with unique electronic structures and unusual properties that can be exploited in the field of nanomaterials and biomedical science.

Endohedral metallofullerenes (EMFs) are one such class of molecules, in which one or more metal atoms are encapsulated inside many kinds of carbon cages. Crucially, the metal atom(s) are not chemically bonded with the carbon surrounds, but they do donate electrons to the carbon cage. Scientists have recently begun to understand how to control the movement, behavior and positioning of the enclosed atoms by adding other atoms, such as silicon or germanium (in their silyl or germyl groups), to the fullerene surface. This allows for the manipulation and fine-tuning of the EMF’s properties.

Now, Masahiro Kako and co-workers at the University of Electro-Communications in Tokyo, together with scientists across Japan and the USA, have created and analyzed the effects of silylation and germylation on an EMF called Lu3N@Ih-C80 (three lutetium atoms bonded to a nitrogen atom encased inside a carbon 80 cage).

Using X-ray crystallography, electrochemical analyses and theoretical calculations, the team discovered that adding silyl groups or germyl groups to the fullerene structure was a versatile way of controlling the EMF’s electronic properties. The exact positioning of the silyl or germyl groups in bonding to the carbon structure determined the energy gaps present in the EMF, and determined the orientation of the bonded metal atoms inside the cage.

The germyl groups donated more electrons and the process worked slightly more efficiently than the silyl groups, but Kako and his team believe that both provide an effective way of fine-tuning EMF electronic characteristics.

Background

A brief history of fullerenes

Fullerenes are carbon molecules that take the shape of spheres. The most famous and abundant fullerene is the buckminsterfullerene, or ‘buckyball’, C60, which resembles a soccer ball in shape with a bonded carbon atom at each point of every polygon.

Endohedral metallofullerenes, or EMFs, are created by trapping a metal atom or atoms inside a fullerene cage, rather like a hamster in a ball. The trapped atom(s) are not chemically-bonded to the carbon, but they do interact with it by donating electrons, thus creating unique and very useful molecules for nanomaterial science and biomedicine.

Silylation and germylation

The addition of other atoms to fullerene surfaces can affect EMF properties, by regulating the behavior of the metal atoms inside the fullerene cage. In one EMF, the movement of lanthanum atoms is restricted to two dimensions by the addition of silyl groups to the carbon cage. This alters the electrostatic potentials inside the cage and restricts the lanthanum atoms’ mobility, and thus changes the overall properties of the whole molecule.

This study by Masahiro Kako and co-workers further enhances understanding of the effects of silylation and germalytion (the addition of silicon-based and germanium-based groups) on lutetium-based EMFs. The team have shown that the exact positioning of the additional atoms in the carbon structure can influence the energy gaps across the molecule, thereby allowing them to tune the electronic properties of the EMF. This ability to ‘fine-tune’ EMFs could have some applications for functional materials in molecular electronics, such as acceptors in organic photovoltaic devices.

Further work

Kako and his team hope to carry out further investigations into the addition of alternative groups of atoms to fullerenes, to add to the tuning properties of silicon- and germanium-based groups. This could expand on the versatility of EMFs and their potential applications in future.

Fullerenes don’t get that much attention these days when compared to graphene and carbon nanotubes although there seems to be increasing interest in their potential as cages.

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

Preparation, Structural Determination, and Characterization of Electronic Properties of Bis-Silylated and Bis-Germylated Lu3N@Ih-C80 by Prof. Dr. Masahiro Kako, Kyosuke Miyabe, Dr. Kumiko Sato, Dr. Mitsuaki Suzuki, Dr. Naomi Mizorogi, Dr. Wei-Wei Wang, Prof. Dr. Michio Yamada, Prof. Dr. Yutaka Maeda, Prof. Dr. Marilyn M. Olmstead, Prof. Dr. Alan L. Balch, Prof. Dr. Shigeru Nagase, and Prof. Dr. Takeshi Akasaka. Chemistry – A European Journal DOI: 10.1002/chem.201503579 Article first published online: 21 SEP 2015

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Nanoislands and skeletal skin for fuel cells

This final item concerns a platinum ‘skin’. From an Oct. 21, 2015 University of Electro-Communications press release,

Polymer electrolyte fuel cells (PEFC) could provide an alternative to traditional fossil fuel power, but higher performance and durability under harsh conditions are needed before PEFC vehicles can be considered commercially viable. Now researchers at the University of Electro-Communications, the University of Tokushima and Japan Synchrotron Radiation Research Institute in Japan have synthesised catalysts from platinum cobalt (PtCo3) nanoparticles on carbon (C) with tin oxide (SnO2) nanoislands and shown that they perform better than any previously reported.

Fuel cell research has focused on platinum alloys and transition metal oxides to improve on the durability and catalytic performance of platinum on carbon. Previous work with SnO2 islands grown on platinum tin alloy with carbon had already shown some improvement in the oxygen reduction reactions that occur in fuel cells. However growing islands of only SnO2 on other alloys posed a challenge.

Now Yasuhiro Iwasawa at the University of Electro-Communications and his colleagues have grown SnO2 islands on Pt3Co nanoparticles on carbon (Pt3Co/C) by selective electrochemical deposition of tin metal, which is then oxidized. The addition of the SnO2 nanoislands doubled the catalytic performance of the Pt3Co/C catalysts. In addition they were undamaged after undergoing 5000 cycles of voltage changes to test their durability.

The structure the Pt3Co nanoparticles form has a Pt3Co core surrounded by a platinum skin that has a rough – “skeleton” – morphology. The researchers attribute the high catalytic performance in part to efficient electronic modification specifically at the platinum skin surface, and in particular to the unique property of the SnO2 nanoislands at the compressive platinum skeleton-skin surface.

“In general, adhesion of transition metal oxides on carbon induces depression of the electrical conductivity of the carbon,” explain the researchers in their report. “Hence, the selective nano-SnO2 decoration on the Pt-enriched-surface nanoparticles provides a significant advantage as a cathode catalyst.”

Background

Polymer electrolyte fuel cells

Polymer electrolyte fuel cells consist of two porous polymer membranes. On one side hydrogen gas molecules give up electrons and on the other oxygen gas molecules accept electrons completing a current circuit.  The ions can then penetrate the membrane and combine to form water.

Polymer electrolyte fuel cells have several advantages over conventional fuel as they do not deplete the limited supplies of fossil fuels, and the waste products are water and heat, and therefore relatively non-polluting. The efficiency of fuel cells has already highlighted their potential for powering small vehicles.

Redox

The formation of hydrogen and oxygen ions from the gas molecules are referred to as redox reactions from the term ‘reduction’ and ‘oxidation’. In fuel cells neutral oxygen molecules are reduced to negatively charge oxygen ions with a charge of -2. The oxidation number is thus ‘reduced’ from 0 to -2. In contrast, ionisation of hydrogen molecules to positively charge hydrogen ions (that is single protons) increases the oxygen number by one – ‘oxidation’.

Catalysts are used to increase the efficiency of the redox reactions in fuel cells to improve the power and current density. The efficiency of the catalysts is measured in terms of the oxygen reduction reaction (ORR) activity.

Improving ORR

The researchers measured the potential difference required for other reactions in the presence of their catalyst to determine how the additional SnO2 islands improved the ORR. Their observations suggest that strain at the nanoislands on the Pt3Co nanoparticles modifies the electronic structure so that the centre of the electron d band is decreased. This decreases oxygen adsorption and improves the performance of the catalyst. In addition there is an increase in the proton affinity of the platinum near the nanoislands, which significantly enhances the ORR further still.

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

Surface-Regulated Nano-SnO2/Pt3Co/C Cathode Catalysts for Polymer Electrolyte Fuel Cells Fabricated by a Selective Electrochemical Sn Deposition Method by Kensaku Nagasawa, Shinobu Takao, Shin-ichi Nagamatsu, Gabor Samjeské, Oki Sekizawa, Takuma Kaneko, Kotaro Higashi, Takashi Yamamoto, Tomoya Uruga†, and Yasuhiro Iwasawa. J. Am. Chem. Soc., 2015, 137 (40), pp 12856–12864 DOI: 10.1021/jacs.5b04256 Publication Date (Web): September 27, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.

A use for fullerenes—inside insulation plastic for high-voltage cables

A Jan. 27, 2015 news item on Nanowerk, describes research which suggests that there may a new use for buckminsterfullerenes (or what they’re calling ‘carbon nanoballs’),

Researchers at Chalmers University of Technology [Sweden] have discovered that the insulation plastic used in high-voltage cables can withstand a 26 per cent higher voltage if nanometer-sized carbon balls are added. This could result in enormous efficiency gains in the power grids of the future, which are needed to achieve a sustainable energy system.

The renewable energy sources of tomorrow will often be found far away from the end user. Wind turbines, for example, are most effective when placed out at sea. Solar energy will have the greatest impact on the European energy system if focus is on transport of solar power from North Africa and Southern Europe to Northern Europe.

“Reducing energy losses during electric power transmission is one of the most important factors for the energy systems of the future,” says Chalmers researcher Christian Müller. “The other two are development of renewable energy sources and technologies for energy storage.”

The Jan. 27, 2015 Chalmers University of Technology press release (also on EurekAlert) by Johanna Wilde, which originated the news item, provides more information about the research,

Together with colleagues from Chalmers and the company Borealis in Stenungsund, he [Müller] has found a powerful method for reducing energy losses in alternating current cables.  The results were recently published in Advanced Materials, a highly ranked scientific journal.

The researchers have shown that different variants of the C60 carbon ball, a nanomaterial in the fullerene molecular group, provide strong protection against breakdown of the insulation plastic used in high-voltage cables. Today the voltage in the cables has to be limited to prevent the insulation layer from getting damaged. The higher the voltage the more electrons can leak out into the insulation material, a process which leads to breakdown.

It is sufficient to add very small amounts of fullerene to the insulation plastic for it to withstand a voltage that is 26 per cent higher, without the material breaking down, than the voltage that plastic without the additive can withstand.

“Being able to increase the voltage to this extent would result in enormous efficiency gains in power transmission all over the world,” says Christian Müller. “A major issue in the industry is how transmission efficiency can be improved without making the power cables thicker, since they are already very heavy and difficult to handle.”

Using additives to protect the insulation plastic has been a known concept since the 1970s, but until now it has been unknown exactly what and how much to add. Consequently, additives are currently not used at all for the purpose, and the insulation material is manufactured with the highest possible degree of chemical purity.

In recent years, other researchers have experimented with fullerenes in the electrically conductive parts of high-voltage cables. Until now, though, it has been unknown that the substance can be beneficial for the insulation material.

The Chalmers researchers have now demonstrated that fullerenes are the best voltage stabilizers identified for insulation plastic thus far. This means they have a hitherto unsurpassed ability to capture electrons and thus protect other molecules from being destroyed by the electrons.

To arrive at these findings, the researchers tested a number of molecules that are also used within organic solar cell research at Chalmers. The molecules were tested using several different methods, and were added to pieces of insulation plastic used for high-voltage cables. The pieces of plastic were then subjected to an increasing electric field until they crackled. Fullerenes turned out to be the type of additive that most effectively protects the insulation plastic.

The press release includes some facts about buckyballs or buckminsterfullerenes or fullerenes or C60 or carbon nanoballs, depending on what you want to call them,

 Facts: Carbon ball C60

  • The C60 carbon ball is also called buckminsterfullerene. It consists of 60 carbon atoms that are placed so that the molecule resembles a nanometer-sized football. C60 is included in the fullerene molecular class.
  • Fullerenes were discovered in 1985, which resulted in the Nobel Prize in Chemistry in 1996. They have unique electronic qualities and have been regarded as very promising material for several applications. Thus far, however, there have been few industrial usage areas.
  • Fullerenes are one of the five forms of pure carbon that exist. The other four are graphite, graphene/carbon nanotubes, diamond and amorphous carbon, for example soot.

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

A New Application Area for Fullerenes: Voltage Stabilizers for Power Cable Insulation by Markus Jarvid, Anette Johansson, Renee Kroon, Jonas M. Bjuggren, Harald Wutzel, Villgot Englund, Stanislaw Gubanski, Mats R. Andersson, and Christian Müller. Advanced Materials DOI: 10.1002/adma.201404306 Article first published online: 12 DEC 2014

© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

Here’s an image of wind turbines, an example of equipment which could benefit greatly from better insulation.,

Images: Lina Bertling, Jan-Olof Yxell, Carolina Eek Jaworski, Anette Johansson, Markus Jarvid, Christian Müller

Images: Lina Bertling, Jan-Olof Yxell, Carolina Eek Jaworski, Anette Johansson, Markus Jarvid, Christian Müller

You can find this image and others by clicking on the Chalmers University press release link (assuming the page hasn’t been moved). You can find more information about Borealis (the company Müller is working with) here.

The evolution of molecules as observed with femtosecond stimulated Raman spectroscopy

A July 3, 2014 news item on Azonano features some recent research from the Université de Montréal (amongst other institutions),

Scientists don’t fully understand how ‘plastic’ solar panels work, which complicates the improvement of their cost efficiency, thereby blocking the wider use of the technology. However, researchers at the University of Montreal, the Science and Technology Facilities Council, Imperial College London and the University of Cyprus have determined how light beams excite the chemicals in solar panels, enabling them to produce charge.

A July 2, 2014 University of Montreal news release, which originated the news item, provides a fascinating description of the ultrafast laser process used to make the observations,

 “We used femtosecond stimulated Raman spectroscopy,” explained Tony Parker of the Science and Technology Facilities Council’s Central Laser Facility. “Femtosecond stimulated Raman spectroscopy is an advanced ultrafast laser technique that provides details on how chemical bonds change during extremely fast chemical reactions. The laser provides information on the vibration of the molecules as they interact with the pulses of laser light.” Extremely complicated calculations on these vibrations enabled the scientists to ascertain how the molecules were evolving. Firstly, they found that after the electron moves away from the positive centre, the rapid molecular rearrangement must be prompt and resemble the final products within around 300 femtoseconds (0.0000000000003 s). A femtosecond is a quadrillionth of a second – a femtosecond is to a second as a second is to 3.7 million years. This promptness and speed enhances and helps maintain charge separation.  Secondly, the researchers noted that any ongoing relaxation and molecular reorganisation processes following this initial charge separation, as visualised using the FSRS method, should be extremely small.

As for why the researchers’ curiosity was stimulated (from the news release),

The researchers have been investigating the fundamental beginnings of the reactions that take place that underpin solar energy conversion devices, studying the new brand of photovoltaic diodes that are based on blends of polymeric semiconductors and fullerene derivatives. Polymers are large molecules made up of many smaller molecules of the same kind – consisting of so-called ‘organic’ building blocks because they are composed of atoms that also compose molecules for life (carbon, nitrogen, sulphur). A fullerene is a molecule in the shape of a football, made of carbon. “In these and other devices, the absorption of light fuels the formation of an electron and a positive charged species. To ultimately provide electricity, these two attractive species must separate and the electron must move away. If the electron is not able to move away fast enough then the positive and negative charges simple recombine and effectively nothing changes. The overall efficiency of solar devices compares how much recombines and how much separates,” explained Sophia Hayes of the University of Cyprus, last author of the study.

… “Our findings open avenues for future research into understanding the differences between material systems that actually produce efficient solar cells and systems that should as efficient but in fact do not perform as well. A greater understanding of what works and what doesn’t will obviously enable better solar panels to be designed in the future,” said the University of Montreal’s Carlos Silva, who was senior author of the study.

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

Direct observation of ultrafast long-range charge separation at polymer–fullerene heterojunctions by Françoise Provencher, Nicolas Bérubé, Anthony W. Parker, Gregory M. Greetham, Michael Towrie, Christoph Hellmann, Michel Côté, Natalie Stingelin, Carlos Silva & Sophia C. Hayes. Nature Communications 5, Article number: 4288 doi:10.1038/ncomms5288 Published 01 July 2014

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