Tag Archives: carbon

Psst: secret marriage … Buckyballs and Graphene get together!

A March 1, 2018 news item on Nanowerk announces  a new coupling,

Scientists combined buckyballs, [also known as buckminsterfullerenes, fullerenes, or C60] which resemble tiny soccer balls made from 60 carbon atoms, with graphene, a single layer of carbon, on an underlying surface. Positive and negative charges can transfer between the balls and graphene depending on the nature of the surface as well as the structural order and local orientation of the carbon ball. Scientists can use this architecture to develop tunable junctions for lightweight electronic devices.

The researchers have made this illustration of their work available,

Researchers are developing new, lightweight electronics that rapidly conduct electricity by covering a sheet of carbon (graphene) with buckyballs. Electricity is the flow of electrons. On these lightweight structures, electrons as well as positive holes (missing electrons) transfer between the balls and graphene. The team showed that the crystallinity and orientation of the balls, as well as the underlying layer, affected this charge transfer. The top image shows a calculation of the charge density for a specific orientation of the balls on graphene. The blue represents positive charges, while the red is negative. The bottom image shows that the balls are in a close-packed structure. The bright dots correspond to the projected images of columns of buckyball molecules. Courtesy: US Department of Energy Office of Science

A February 28, 2018 US Department of Energy (DoE) Office of Science news release, which originated the news item, provides more detail,

The Impact

Fast-moving electrons and their counterpart, holes, were preserved in graphene with crystalline buckyball overlayers. Significantly, the carbon ball provides charge transfer to the graphene. Scientists expect the transfer to be highly tunable with external voltages. This marriage has ramifications for smart electronics that run longer and do not break as easily, bringing us closer to sensor-embedded smart clothing and robotic skin.

Summary

Charge transfer at the interface between dissimilar materials is at the heart of almost all electronic technologies such as transistors and photovoltaic devices. In this study, scientists studied charge transfer at the interface region of buckyball molecules deposited on graphene, with and without a supporting substrate, such as hexagonal boron nitride. They employed ab initio density functional theory with van der Waals interactions to model the structure theoretically. Van der Waals interactions are weak connections between neutral molecules. The team used high-resolution transmission electron microscopy and electronic transport measurements to characterize experimentally the properties of the interface. The researchers observed that charge transfer between buckyballs and the graphene was sensitive to the nature of the underlying substrate, in addition, to the crystallinity and local orientation of the buckyballs. These studies open an avenue to devices where buckyball layers on top of graphene can serve as electron acceptors and other buckyball layers as electron donors. Even at room temperature, buckyball molecules were orientationally locked into position. This is in sharp contrast to buckyball molecules in un-doped bulk crystalline configurations, where locking occurs only at low temperature. High electron and hole mobilities are preserved in graphene with crystalline buckyball overlayers. This finding has ramifications for the development of organic high-mobility field-effect devices and other high mobility applications.

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

Molecular Arrangement and Charge Transfer in C60 /Graphene Heterostructures by Claudia Ojeda-Aristizabal, Elton J. G. Santos, Seita Onishi, Aiming Yan, Haider I. Rasool, Salman Kahn, Yinchuan Lv, Drew W. Latzke, Jairo Velasco Jr., Michael F. Crommie, Matthew Sorensen, Kenneth Gotlieb, Chiu-Yun Lin, Kenji Watanabe, Takashi Taniguchi, Alessandra Lanzara, and Alex Zettl. ACS Nano, 2017, 11 (5), pp 4686–4693 DOI: 10.1021/acsnano.7b00551 Publication Date (Web): April 24, 2017

Copyright © 2017 American Chemical Society

This paper is behind a paywall.

Do you want that coffee with some graphene on toast?

These scientists are excited:

For those who prefer text, here’s the Rice University Feb. 13, 2018 news release (received via email and available online here and on EurekAlert here) Note: Links have been removed),

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

The Air Force Office of Scientific Research supported the research.

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

Laser-Induced Graphene by Multiple Lasing: Toward Electronics on Cloth, Paper, and Food by Yieu Chyan, Ruquan Ye†, Yilun Li, Swatantra Pratap Singh, Christopher J. Arnusch, and James M. Tour. ACS Nano DOI: 10.1021/acsnano.7b08539 Publication Date (Web): February 13, 2018

Copyright © 2018 American Chemical Society

This paper is behind a paywall.

h/t Feb. 13, 2018 news item on Nanowerk

Bulletproof graphene

A December 18, 2017 news item on Nanowerk announces research that demonstrates graphene can be harder than diamonds (Note: A link has been removed),

Imagine a material as flexible and lightweight as foil that becomes stiff and hard enough to stop a bullet on impact. In a newly published paper in Nature Nanotechnology (“Ultrahard carbon film from epitaxial two-layer graphene”), researchers across The City University of New York (CUNY) describe a process for creating diamene: flexible, layered sheets of graphene that temporarily become harder than diamond and impenetrable upon impact.

Scientists at the Advanced Science Research Center (ASRC) at the Graduate Center, CUNY, worked to theorize and test how two layers of graphene — each one-atom thick — could be made to transform into a diamond-like material upon impact at room temperature. The team also found the moment of conversion resulted in a sudden reduction of electric current, suggesting diamene could have interesting electronic and spintronic properties. The new findings will likely have applications in developing wear-resistant protective coatings and ultra-light bullet-proof films.

A December 18, 2017 CUNY news release, which originated the news item, provides a little more detail,

“This is the thinnest film with the stiffness and hardness of diamond ever created,” said Elisa Riedo, professor of physics at the ASRC and the project’s lead researcher. “Previously, when we tested graphite or a single atomic layer of graphene, we would apply pressure and feel a very soft film. But when the graphite film was exactly two-layers thick, all of a sudden we realized that the material under pressure was becoming extremely hard and as stiff, or stiffer, than bulk diamond.”

Angelo Bongiorno, associate professor of chemistry at CUNY College of Staten Island and part of the research team, developed the theory for creating diamene. He and his colleagues used atomistic computer simulations to model potential outcomes when pressurizing two honeycomb layers of graphene aligned in different configurations. Riedo and other team members then used an atomic force microscope to apply localized pressure to two-layer graphene on silicon carbide substrates and found perfect agreement with the calculations. Experiments and theory both show that this graphite-diamond transition does not occur for more than two layers or for a single graphene layer.

“Graphite and diamonds are both made entirely of carbon, but the atoms are arranged differently in each material, giving them distinct properties such as hardness, flexibility and electrical conduction,” Bongiorno said. “Our new technique allows us to manipulate graphite so that it can take on the beneficial properties of a diamond under specific conditions.”

The research team’s successful work opens up possibilities for investigating graphite-to-diamond phase transition in two-dimensional materials, according to the paper. Future research could explore methods for stabilizing the transition and allow for further applications for the resulting materials.

There’s an artist’s representation of a bullet’s impact on graphene,

By applying pressure at the nanoscale with an indenter to two layers of graphene, each one-atom thick, CUNY researchers transformed the honeycombed graphene into a diamond-like material at room temperature. Photo credit: Ella Maru Studio Courtesy: CUNY

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

Ultrahard carbon film from epitaxial two-layer graphene by Yang Gao, Tengfei Cao, Filippo Cellini, Claire Berger, Walter A. de Heer, Erio Tosatti, Elisa Riedo, & Angelo Bongiorno. Nature Nanotechnology (2017) doi:10.1038/s41565-017-0023-9 Published online: 18 December 2017

This paper is behind a paywall.

Calligraphy ink and cancer treatment

Courtesy of ACS Omega and the researchers

Nice illustration! I wish I could credit the artist. For anyone who needs a little text to make sense of it, there’s a Sept. 27, 2017 news item on Nanowerk (Note: A link has been removed),

For hundreds of years, Chinese calligraphers have used a plant-based ink to create beautiful messages and art. Now, one group reports in ACS Omega (“New Application of Old Material: Chinese Traditional Ink for Photothermal Therapy of Metastatic Lymph Nodes”) that this ink could noninvasively and effectively treat cancer cells that spread, or metastasize, to lymph nodes.

A Sept. 27, 2017 American Chemical Society (ACS) news release, which originated the news item, reveals more about the research,

As cancer cells leave a tumor, they frequently make their way to lymph nodes, which are part of the immune system. In this case, the main treatment option is surgery, but this can result in complications. Photothermal therapy (PTT) is an emerging noninvasive treatment option in which nanomaterials are injected and accumulate in cancer cells. A laser heats up the nanomaterials, and this heat kills the cells. Many of these nanomaterials are expensive, difficult-to-make and toxic. However, a traditional Chinese ink called Hu-Kaiwen ink (Hu-ink) has similar properties to the nanomaterials used in PTT. For example, they are the same color, and are both carbon-based and stable in water. So Wuli Yang and colleagues wanted to see if Hu-ink could be a good alternative material for PTT.

The researchers analyzed Hu-ink and found that it consists of nanoparticles and thin layers of carbon. When Hu-ink was heated with a laser, its temperature rose by 131 degrees Fahrenheit, much higher than current nanomaterials. Under PPT conditions, the Hu-ink killed cancer cells in a laboratory dish, but under normal conditions, the ink was non-toxic. This was also the scenario observed in mice with tumors. The researchers also noted that Hu-ink could act as a probe to locate tumors and metastases because it absorbs near-infrared light, which goes through skin.

Being a little curious about Hu-ink’s similarity to nanomaterial, I looked for more detail in the the paper (Note: Links have been removed), From the: Introduction,

Photothermal therapy (PTT) is an emerging tumor treatment strategy, which utilizes hyperthermia generated from absorbed near-infrared (NIR) light energy by photoabsorbing agents to kill tumor cells.(7-13) Different from chemotherapy, surgical treatment, and radiotherapy, PTT is noninvasive and more efficient.(7, 14, 15) In the past decade, PTT with diverse nanomaterials to eliminate cancer metastases lymph nodes has attracted extensive attention by several groups, including our group.(3, 16-20) For instance, Liu and his co-workers developed a treatment method based on PEGylated single-walled carbon nanotubes for PTT of tumor sentinel lymph nodes and achieved remarkably improved treatment effect in an animal tumor model.(21) To meet the clinical practice, the potential metastasis of deeper lymph nodes was further ablated in our previous work, using magnetic graphene oxide as a theranostic agent.(22) However, preparation of these artificial nanomaterials usually requires high cost, complicated synthetic process, and unavoidably toxic catalyst or chemicals,(23, 24) which impede their future clinical application. For the clinical application, exploring an environment-friendly material with simple preparation procedure, good biocompatibility, and excellent therapeutic efficiency is still highly desired. [emphases mine]

From the: Preparation and Characterization of Hu-Ink

To obtain an applicable sample, the condensed Hu-ink was first diluted into aqueous dispersion with a lower concentration. The obtained Hu-ink dispersion without any further treatment was black in color and stable in physiological environment, including water, phosphate-buffered saline (PBS), and Roswell Park Memorial Institute (RPMI) 1640; furthermore, no aggregation was observed even after keeping undisturbed for 3 days (Figure 2a). The nanoscaled morphology of Hu-ink was examined by transmission electron microscopy (TEM) (Figure 2b), which demonstrates that Hu-ink mainly exist in the form of small aggregates. These small aggregates consist of a few nanoparticles with diameter of about 20–50 nm. Dynamic light scattering (DLS) measurement (Figure 2c) further shows that Hu-ink aqueous dispersion possesses a hydrodynamic diameter of about 186 nm (polydispersity index: 0.18), which was a crucial prerequisite for biomedical applications.(29) In the X-ray diffraction (XRD) pattern, no other characteristic peaks are found except carbon peak (Figure S1, Supporting Information), which confirms that the main component of Hu-ink is carbon.(25) Raman spectroscopy was a common tool to characterize graphene-related materials.(30) D band (∼1300 cm–1, corresponding to the defects) and G band (∼1600 cm–1, related to the sp2 carbon sites) peaks could be observed in Figure 2d with the ratio ID/IG = 0.96, which confirms the existence of graphene sheetlike structure in Hu-ink.(31) The UV–vis–NIR spectra (Figure 2e) also revealed that Hu-ink has high absorption in the NIR region around 650–900 nm, in which hemoglobin and water, the major absorbers of biological tissue, have their lowest absorption coefficient.(32) The high NIR absorption capability of Hu-ink encouraged us to investigate its photothermal properties.(33-35) Hu-ink dispersions with different concentrations were irradiated under an 808 nm laser (the commercial and widely used wavelength in photothermal therapy).(8-13) [emphases mine]

Curiosity satisfied! For those who’d like to investigate even further, here’s a link to and a citation for the paper,

New Application of Old Material: Chinese Traditional Ink for Photothermal Therapy of Metastatic Lymph Nodes by Sheng Wang, Yongbin Cao, Qin Zhang, Haibao Peng, Lei Liang, Qingguo Li, Shun Shen, Aimaier Tuerdi, Ye Xu, Sanjun Cai, and Wuli Yang. ACS Omega, 2017, 2 (8), pp 5170–5178 DOI: 10.1021/acsomega.7b00993 Publication Date (Web): August 30, 2017

Copyright © 2017 American Chemical Society

This paper appears to be open access.

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))

Buckydiamondoids steer electron flow

One doesn’t usually think about buckyballs (Buckminsterfullerenes) and diamondoids as being together in one molecule but that has not stopped scientists from trying to join them and, in this case, successfully. From a Sept. 9, 2014 news item on ScienceDaily,

Scientists have married two unconventional forms of carbon — one shaped like a soccer ball, the other a tiny diamond — to make a molecule that conducts electricity in only one direction. This tiny electronic component, known as a rectifier, could play a key role in shrinking chip components down to the size of molecules to enable faster, more powerful devices.

Here’s an illustration the scientists have provided,

Illustration of a buckydiamondoid molecule under a scanning tunneling microscope (STM). In this study the STM made images of the buckydiamondoids and probed their electronic properties.

Illustration of a buckydiamondoid molecule under a scanning tunneling microscope (STM). In this study the STM made images of the buckydiamondoids and probed their electronic properties.

A Sept. 9, 2014 Stanford University news release by Glenda Chui (also on EurekAlert), which originated the news item, provides some information about this piece of international research along with background information on buckyballs and diamondoids (Note: Links have been removed),

“We wanted to see what new, emergent properties might come out when you put these two ingredients together to create a ‘buckydiamondoid,'” said Hari Manoharan of the Stanford Institute for Materials and Energy Sciences (SIMES) at the U.S. Department of Energy’s SLAC National Accelerator Laboratory. “What we got was basically a one-way valve for conducting electricity – clearly more than the sum of its parts.”

The research team, which included scientists from Stanford University, Belgium, Germany and Ukraine, reported its results Sept. 9 in Nature Communications.

Many electronic circuits have three basic components: a material that conducts electrons; rectifiers, which commonly take the form of diodes, to steer that flow in a single direction; and transistors to switch the flow on and off. Scientists combined two offbeat ingredients – buckyballs and diamondoids – to create the new diode-like component.

Buckyballs – short for buckminsterfullerenes – are hollow carbon spheres whose 1985 discovery earned three scientists a Nobel Prize in chemistry. Diamondoids are tiny linked cages of carbon joined, or bonded, as they are in diamonds, with hydrogen atoms linked to the surface, but weighing less than a billionth of a billionth of a carat. Both are subjects of a lot of research aimed at understanding their properties and finding ways to use them.

In 2007, a team led by researchers from SLAC and Stanford discovered that a single layer of diamondoids on a metal surface can emit and focus electrons into a tiny beam. Manoharan and his colleagues wondered: What would happen if they paired an electron-emitting diamondoid with another molecule that likes to grab electrons? Buckyballs are just that sort of electron-grabbing molecule.

Details are then provided about this specific piece of research (from the Stanford news release),

For this study, diamondoids were produced in the SLAC laboratory of SIMES researchers Jeremy Dahl and Robert Carlson, who are world experts in extracting the tiny diamonds from petroleum. The diamondoids were then shipped to Germany, where chemists at Justus-Liebig University figured out how to attach them to buckyballs.

The resulting buckydiamondoids, which are just a few nanometers long, were tested in SIMES laboratories at Stanford. A team led by graduate student Jason Randel and postdoctoral researcher Francis Niestemski used a scanning tunneling microscope to make images of the hybrid molecules and measure their electronic behavior. They discovered that the hybrid is an excellent rectifier: The electrical current flowing through the molecule was up to 50 times stronger in one direction, from electron-spitting diamondoid to electron-catching buckyball, than in the opposite direction. This is something neither component can do on its own.

While this is not the first molecular rectifier ever invented, it’s the first one made from just carbon and hydrogen, a simplicity researchers find appealing, said Manoharan, who is an associate professor of physics at Stanford. The next step, he said, is to see if transistors can be constructed from the same basic ingredients.

“Buckyballs are easy to make – they can be isolated from soot – and the type of diamondoid we used here, which consists of two tiny cages, can be purchased commercially,” he said. “And now that our colleagues in Germany have figured out how to bind them together, others can follow the recipe. So while our research was aimed at gaining fundamental insights about a novel hybrid molecule, it could lead to advances that help make molecular electronics a reality.”

Other research collaborators came from the Catholic University of Louvain in Belgium and Kiev Polytechnic Institute in Ukraine. The primary funding for the work came from U.S. the Department of Energy Office of Science (Basic Energy Sciences, Materials Sciences and Engineering Divisions).

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

Unconventional molecule-resolved current rectification in diamondoid–fullerene hybrids by Jason C. Randel, Francis C. Niestemski,    Andrés R. Botello-Mendez, Warren Mar, Georges Ndabashimiye, Sorin Melinte, Jeremy E. P. Dahl, Robert M. K. Carlson, Ekaterina D. Butova, Andrey A. Fokin, Peter R. Schreiner, Jean-Christophe Charlier & Hari C. Manoharan. Nature Communications 5, Article number: 4877 doi:10.1038/ncomms5877 Published 09 September 2014

This paper is open access. The scientists provided not only a standard illustration but a pretty picture of the buckydiamondoid,

Caption: An international team led by researchers at SLAC National Accelerator Laboratory and Stanford University joined two offbeat carbon molecules -- diamondoids, the square cages at left, and buckyballs, the soccer-ball shapes at right -- to create "buckydiamondoids," center. These hybrid molecules function as rectifiers, conducting electrons in only one direction, and could help pave the way to molecular electronic devices. Credit: Manoharan Lab/Stanford University

Caption: An international team led by researchers at SLAC National Accelerator Laboratory and Stanford University joined two offbeat carbon molecules — diamondoids, the square cages at left, and buckyballs, the soccer-ball shapes at right — to create “buckydiamondoids,” center. These hybrid molecules function as rectifiers, conducting electrons in only one direction, and could help pave the way to molecular electronic devices.
Credit: Manoharan Lab/Stanford University

Stabilizing a carbon-gold complex (gold carbene shines green)

If you find carbon bonds and catalysis interesting, this is the posting for you. A July 8, 2014 news item on Nanowerk highlights research at Heidelberg University (Germany; Note: A link has been removed),

With a chemical “trick”, scientists at Heidelberg University have succeeded in isolating a stable gold carbene complex. Chemist Prof. Dr. Bernd F. Straub and his team are the first to have created the basis for directly examining the otherwise unstable gold-carbon double bond. Prof. Straub explains that highly reactive gold carbene molecules play an important role in landmark catalysing processes taking place at high speed. The research findings have been published in the German and the international edition of Angewandte Chemie (“Isolation of a Non-Heteroatom-Stabilized Gold–Carbene Complex”).

A July 8, 2014 Heidelberg University press release, which originated the news item, describes the catalytic process in general and the specific complex created by the researchers,

Chemical reactions can be accelerated with the aid of catalysts; consequently materials and pharmaceuticals can be manufactured from the raw materials of nature. The study of gold compounds in catalytic processes has proved particularly intensive and successful, according to Prof. Straub. “In numerous scientific studies in the last ten years, experts have been proposing gold carbenes as essential short-lived intermediates in catalytic reactions,” the Heidelberg researcher explains. However, with their high reactivity they escape detailed study: hardly has a gold carbene fragment consisting of the elements gold and carbon emerged – Au for aurum and C for carbon – when it continues to react.

In order to first create a stable complex and isolate a gold carbene structure for research, the two elements were “lured into a cage like a hungry tiger with a bait,” says Matthias Hussong, who is working on his doctoral dissertation in Prof. Straub’s team. The researchers first shielded the gold and carbon from its environment by surrounding them with low-reactive, space-filling chemical groups. Then the two elements were bonded in a carefully planned step – and so the Au=C fragment was “caught” in the gold carbene complex.

The chemists were able to impart “an amazing stability” to the gold carbene, says Prof. Straub – and at the same time to make it literally visible. “Almost all gold complexes are colourless, while the ‘stable’ gold carbene is emerald green,” states the scientist, who heads a research group at Heidelberg University‘s Institute of Organic Chemistry. Further Heidelberg studies showed that gold in its compounds is more than a “soft proton”, as the chemical behaviour of gold had been described to date.

If the gold fragment is replaced by a “real” proton, e.g. the nucleus of hydrogen, the lightest element, this analogous protonated carbene displays a reddish purple colour. “The gold in the gold carbene complex behaves differently from a proton – that is very clear to the eye,” states Prof. Straub. He and his team are now continuing to explore the understanding of gold catalysis, with the aim of using these findings to make catalytic processes more efficient.

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

Isolation of a Non-Heteroatom-Stabilized Gold–Carbene Complex by  M. Sc. Matthias W. Hussong, Dr. Frank Rominger, Petra Krämer, and Prof. Dr. Bernd F. Straub. Angewandte Chemie DOI: 10.1002/anie.201404032 Article first published online: 20 JUN 2014

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

This paper is behind a paywall.

All the talk of emerald green reminded me of Angelina Jolie,

'downloaded from: https://www.etsy.com/ca/listing/122299370/emerald-green-earrings-angelina-jolie]

‘downloaded from: https://www.etsy.com/ca/listing/122299370/emerald-green-earrings-angelina-jolie]

The earrings can be found here.

Carbyne vs. graphene

Rice University (Texas, US) researchers are announcing a new carbon-based nanomaterial, carbyne, according an Oct. 9, 2013 news release,

Carbyne will be the strongest of a new class of microscopic materials if and when anyone can make it in bulk.

If they do, they’ll find carbyne nanorods or nanoropes have a host of remarkable and useful properties, as described in a new paper by Rice University theoretical physicist Boris Yakobson and his group. The paper appears this week in the American Chemical Society journal ACS Nano.

Carbyne is a chain of carbon atoms held together by either double or alternating single and triple atomic bonds. That makes it a true one-dimensional material, unlike atom-thin sheets of graphene that have a top and a bottom or hollow nanotubes that have an inside and outside.

According to the portrait drawn from calculations by Yakobson and his group:

* Carbyne’s tensile strength – the ability to withstand stretching – surpasses “that of any other known material” and is double that of graphene. (Scientists had already calculated it would take an elephant on a pencil to break through a sheet of graphene.)

* It has twice the tensile stiffness of graphene and carbon nanotubes and nearly three times that of diamond.

* Stretching carbyne as little as 10 percent alters its electronic band gap significantly.

* If outfitted with molecular handles at the ends, it can also be twisted to alter its band gap. With a 90-degree end-to-end rotation, it becomes a magnetic semiconductor.

Carbyne chains can take on side molecules that may make the chains suitable for energy storage.

* The material is stable at room temperature, largely resisting crosslinks with nearby chains.

That’s a remarkable set of qualities for a simple string of carbon atoms, Yakobson said.

“You could look at it as an ultimately thin graphene ribbon, reduced to just one atom, or an ultimately thin nanotube,” he said. It could be useful for nanomechanical systems, in spintronic devices, as sensors, as strong and light materials for mechanical applications or for energy storage.

“Regardless of the applications,” he said, “academically, it’s very exciting to know the strongest possible assembly of atoms.”

Based on the calculations, he said carbyne might be the highest energy state for stable carbon. “People usually look for what is called the ‘ground state,’ the lowest possible energy configuration for atoms,” Yakobson said. “For carbon, that would be graphite, followed by diamond, then nanotubes, then fullerenes. But nobody asks about the highest energy configuration. We think this may be it, a stable structure at the highest energy possible.”

Theories about carbyne first appeared in the 19th century, and an approximation of the material was first synthesized in the USSR in 1960. Carbyne has since been seen in compressed graphite, has been detected in interstellar dust and has been created in small quantities by experimentalists.

“I have always been interested in the stability of ultimately thin wires of anything and how thin a rod you could make from a given chemical,” Yakobson said. “We had a paper 10 years ago about silicon in which we explored what happens to silicon nanowire as it gets thinner. To me, this was just a part of the same question.”

The Rice researchers, led by Rice graduate student Mingjie Liu and postdoctoral researcher Vasilii Artyukhov, were aware of a number of papers that described one property or another of carbyne. They set out to detail carbyne with computer models using first-principle rules to determine the energetic interactions of atoms, Artyukhov said.

“Our intention was to put it all together, to construct a complete mechanical picture of carbyne as a material,” Artyukhov said. “The fact that it has been observed tells us it’s stable under tension, at least, because otherwise it would just fall apart.”

Yakobson said the researchers were surprised to find that the band gap in carbyne was so sensitive to twisting. “It will be useful as a sensor for torsion or magnetic fields, if you can find a way to attach it to something that will make it twist,” he said. “We didn’t look for this, specifically; it came up as a side product.”

“That’s the good thing about studying things carefully,” Artyukhov said.

Another finding of great interest was the energy barrier that keeps atoms on adjacent carbyne chains from collapsing into each other. “When you’re talking about theoretical material, you always need to be careful to see if it will react with itself,” Artyukhov said. “This has never really been investigated for carbyne.”

The literature seemed to indicate carbyne “was not stable and would form graphite or soot,” he said.

Instead, the researchers found carbon atoms on separate strings might overcome the barrier in one spot, but the rods’ stiffness would prevent them from coming together in a second location, at least at room temperature. “They would look like butterfly wings,” Artyukhov said.

“Bundles might stick to each other, but they wouldn’t collapse completely,” Yakobson added. “That could make for a highly porous, random net that may be good for adsorption.” Artyukhov said the nominal specific area of carbyne is about five times that of graphene.

When the team’s paper became available this summer on arXiv, the scientific press and even some of the popular press were so excited over the calculations that they picked up on the paper and its implications before the team submitted it for peer review. Now that the complete paper is ready for public consumption, the researchers said they’ll carry their investigation in new directions.

They’re taking a more rigorous look at the conductivity of carbyne and are thinking about other elements as well. “We’ve talked about going through different elements in the periodic table to see if some of them can form one-dimensional chains,” Yakobson said.

Given Rice’s prominence in the nanotechnology field and its status as the ‘home’ of the fullerene, aka, buckyballs, this discovery reaffirms the university’s standing.

Here’s a ‘carbyne’ image the researchers have provided,

Rice University researchers have determined from first-principle calculations that carbyne would be the strongest material yet discovered. The carbon-atom chains would be difficult to make but would be twice as strong as two-dimensional graphene sheets. (Credit: Vasilii Artyukhov/Rice University)

Rice University researchers have determined from first-principle calculations that carbyne would be the strongest material yet discovered. The carbon-atom chains would be difficult to make but would be twice as strong as two-dimensional graphene sheets. (Credit: Vasilii Artyukhov/Rice University)

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

Carbyne From First Principles: Chain of C atoms, a Nanorod or a Nanorope by Mingjie Liu , Vasilii I. Artyukhov , Hoonkyung Lee , Fangbo Xu , and Boris I. Yakobson. ACS Nano, Just Accepted Manuscript DOI: 10.1021/nn404177r Publication Date (Web): October 5, 2013
Copyright © 2013 American Chemical Society

This paper is behind a paywall.

ETA Oct. 9, 2013 at 4:40 pm PDT: I forgot to follow through on my headline which refers to graphene, the current ‘wonder’ nanomaterial, and its possible future dethroning by carbyne. I think it unlikely as part of what makes graphene so attractive are the properties that could allow its use in electronics applications, properties which carbyne does not seem to share.

Grossly warped ‘nanographene’, a brand new type of carbon

A new of form carbon sounds exciting although the naming convention escapes me. Why call it ‘nanographene’ (albeit grossly warped) when graphene is already nanoscale? (For anyone who can explain this to me, please do let me know.) A July 15, 2013 news release on EurekAlert (it’s also available as a July 15, 2013 news item on ScienceDaily) describes the new form of carbon,

Bucking planarity, contorted sheets of graphene alter physical, optical and electronic properties of new material

Chemists at Boston College and Nagoya University in Japan have synthesized the first example of a new form of carbon, the team reports in the most recent online edition of the journal Nature Chemistry.

The new material consists of multiple identical pieces of grossly warped graphene, each containing exactly 80 carbon atoms joined together in a network of 26 rings, with 30 hydrogen atoms decorating the rim. Because they measure slightly more than a nanometer across, these individual molecules are referred to generically as “nanocarbons,” or more specifically in this case as “grossly warped nanographenes.”

There’s an explanation of why this discovery is special and how it was made (from,the news release),

Until recently, scientists had identified only two forms of pure carbon: diamond and graphite. Then in 1985, chemists were stunned by the discovery that carbon atoms could also join together to form hollow balls, known as fullerenes. Since then, scientists have also learned how to make long, ultra-thin, hollow tubes of carbon atoms, known as carbon nanotubes, and large flat single sheets of carbon atoms, known as graphene. The discovery of fullerenes was awarded the Nobel Prize in Chemistry in 1996, and the preparation of graphene was awarded the Nobel Prize in Physics in 2010.

Graphene sheets prefer planar, 2-dimensional geometries as a consequence of the hexagonal, chicken wire-like, arrangements of trigonal carbon atoms comprising their two-dimensional networks. The new form of carbon just reported in Nature Chemistry, however, is wildly distorted from planarity as a consequence of the presence of five 7-membered rings and one 5-membered ring embedded in the hexagonal lattice of carbon atoms.

Odd-membered-ring defects such as these not only distort the sheets of atoms away from planarity, they also alter the physical, optical, and electronic properties of the material, according to one of the principle authors, Lawrence T. Scott, the Jim and Louise Vanderslice and Family Professor of Chemistry at Boston College.

“Our new grossly warped nanographene is dramatically more soluble than a planar nanographene of comparable size,” said Scott, “and the two differ significantly in color, as well. Electrochemical measurements revealed that the planar and the warped nanographenes are equally easily oxidized, but the warped nanographene is more difficult to reduce.”

… By introducing multiple odd-membered ring defects into the graphene lattice, Scott and his collaborators have experimentally demonstrated that the electronic properties of graphene can be modified in a predictable manner through precisely controlled chemical synthesis.

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

A grossly warped nanographene and the consequences of multiple odd-membered-ring defects by Katsuaki Kawasumi, Qianyan Zhang, Yasutomo Segawa, Lawrence T. Scott, & Kenichiro Itami. Nature Chemistry (2013) doi:10.1038/nchem.1704  Published online 14 July 2013

This paper is behind a paywall. For those who would like more information but can’t get access to the paper at this time, there’s a brief July 15, 2015 news piece by Caryl Richards on the Chemistry World website.

Blood-, milk-, and mucus-powered electronics

Researchers at Tel Aviv University ([TAU] Israel) have already begun to develop biodegradable display screens in their quest to create electronic devices powered by blood, milk, and mucus proteins found in our bodies. From the March 7, 2012 news item on Nanowerk,

… a team including Ph.D. students Elad Mentovich and Netta Hendler of TAU’s Department of Chemistry and The Center for Nanoscience and Nanotechnology, with supervisor Dr. Shachar Richter and in collaboration with Prof. Michael Gozin and his Ph.D. student Bogdan Belgorodsky, has brought together cutting-edge techniques from multiple fields of science to create protein-based transistors — semi-conductors used to power electronic devices — from organic materials found in the human body. They could become the basis of a new generation of nano-sized technologies that are both flexible and biodegradable.

The March 7, 2012 news release on the American Friend of TAU website notes some of the issues with silicon-based electronics,

One of the challenges of using silicon as a semi-conductor is that a transistor must be created with a “top down” approach. Manufacturers start with a sheet of silicon and carve it into the shape that is needed, like carving a sculpture out of a rock. This method limits the capabilities of transistors when it comes to factors such as size and flexibility.

The TAU researchers turned to biology and chemistry for a different approach to building the ideal transistor. When they applied various combinations of blood, milk, and mucus proteins to any base material, the molecules self-assembled to create a semi-conducting film on a nano-scale. In the case of blood protein, for example, the film is approximately four nanometers high. The current technology in use now is 18 nanometers, says Mentovich.

Together, the three different kinds of proteins create a complete circuit with electronic and optical capabilities, each bringing something unique to the table. Blood protein has the ability to absorb oxygen, Mentovich says, which permits the “doping” of semi-conductors with specific chemicals in order to create specific technological properties. Milk proteins, known for their strength in difficult environments, form the fibers which are the building blocks of the transistors, while the mucosal proteins have the ability to keep red, green and, blue fluorescent dyes separate, together creating the white light emission that is necessary for advanced optics.

Overall, the natural abilities of each protein give the researchers “unique control” over the resulting organic transistor, allowing adjustments for conductivity, memory storage, and fluorescence among other characteristics.

I have previously featured work on vampire (blood-powered) fuel cells and batteries  in my July 18, 2012 posting and my April 3, 2009 posting so the notion of using blood (and presumably other bodily fluids) as a source for electrical power is generating (pun intended, weak though it is) interest in many research labs.

While the researchers don’t speculate about integrating these new carbon-based devices, which are smaller and more flexible than current devices, in bodies (from the American Friends of TAU news release),

Technology is now shifting from a silicon era to a carbon era, notes Mentovich, and this new type of transistor could play a big role. Transistors built from these proteins will be ideal for smaller, flexible devices that are made out of plastic rather than silicon, which exists in wafer form that would shatter like glass if bent. The breakthrough could lead to a new range of flexible technologies, such as screens, cell phones and tablets, biosensors, and microprocessor chips.

Just as significant, because the researchers are using natural proteins to build their transistor, the products they create will be biodegradable. It’s a far more environmentally friendly technology that addresses the growing problem of electronic waste, which is overflowing landfills worldwide.

The biodegradability of these proposed devices may be a problem if they are integrated into our bodies but it is certain that this will be attempted as we continue to explore machine/flesh possibilities.