Hard As Diamond? 43 New Forms of Superhard C…

Hard As Diamond? 43 New Forms of Superhard Carbon Predicted by Scientists.

A study identifies dozens of new carbon structures that are expected to be superhard, including some that may be about as hard as diamonds.

Superhard materials can slice, drill and polish other objects. They also hold potential for creating scratch-resistant coatings that could help keep expensive equipment safe from damage.

Now, science is opening the door to the development of new materials with these seductive qualities.

Researchers have used computational techniques to identify 43 previously unknown forms of carbon that are thought to be stable and superhard — including several predicted to be slightly harder than or nearly as hard as diamonds. Each new carbon variety consists of carbon atoms arranged in a distinct pattern in a crystal lattice.

The study — published on Sept. 3 in the journal npj Computational Materials — combines computational predictions of crystal structures with machine learning to hunt for novel materials. The work is theoretical research, meaning that scientists have predicted the new carbon structures but have not created them yet.

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Using a scanning tunneling microscope to mak…

Using a scanning tunneling microscope to make origami structures out of graphene

A team of researchers from the Chinese Academy of Sciences, Vanderbilt University and the University of Maryland has created origami-like structures made out of graphene using scanning tunneling microscopy. In their paper published in the journal Science, the group explains how they achieved this feat and possible applications.

For several decades, scientists have sought to fold sheets of graphene in controllable ways. While some managed to fold sheets of graphene, they were either not able to do it in a controlled way, or they had to pretreat the graphene to make it bend in certain places. Scientists believe that if graphene sheets could be manipulated controllably, the resulting materials would have desired properties—one example would be bending it at a “magic angle” to make it superconductive. Others hope to develop smaller processors than can be made using silicon. In this new effort, the researchers claim to have found a way to fold nanoislands of graphene controllably.

The first step involved creating the nanoislands of graphene. The researchers fired hydrogen ions at sheets of graphite for 10 cycles, a process that took 10 hours. This produced high-quality graphene that could stand up to manipulation without breaking or bending in unreliable ways. After that, the team used a scanning tunneling microscope (STM) to grab parts of the nanoislands and then to hold onto them as the sheet was folded, much like a piece of paper. They note that it took some expertise on the part of the person controlling the STM to manipulate the sheets accurately.

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You’re not so tough, h-BN: Rice Universi…

You’re not so tough, h-BN: Rice University chemists find new path to make strong 2D material better for applications

Two-dimensional h-BN, an insulating material also known as “white graphene,” is four times stiffer than steel and an excellent conductor of heat, a benefit for composites that rely on it to enhance their properties.

Those qualities also make h-BN hard to modify. Its tight hexagonal lattice of alternating boron and nitrogen atoms is highly resistant to change, unlike graphene and other 2D materials that can be easily modified — aka functionalized — with other elements.

The Rice lab of chemist Angel Martí has published a protocol to enhance h-BN with carbon chains. These turn the 2D tough guy into a material that retains its strength but is more amenable to bonding with polymers or other materials in composites.

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Damaged hearts rewired with nanotube fibers: T…

Damaged hearts rewired with nanotube fibers: Texas Heart doctors confirm Rice-made, conductive carbon threads are electrical bridges

Thin, flexible fibers made of carbon nanotubes have now proven able to bridge damaged heart tissues and deliver the electrical signals needed to keep those hearts beating.

[…]

Scientists at Texas Heart Institute (THI) report they have used biocompatible fibers invented at Rice University in studies that showed sewing them directly into damaged tissue can restore electrical function to hearts.

“Instead of shocking and defibrillating, we are actually correcting diseased conduction of the largest major pumping chamber of the heart by creating a bridge to bypass and conduct over a scarred area of a damaged heart,” said Dr. Mehdi Razavi, a cardiologist and director of Electrophysiology Clinical Research and Innovations at THI, who co-led the study with Rice chemical and biomolecular engineer Matteo Pasquali.

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janeandersonmapractice: Charcoal Properties  W…

janeandersonmapractice:

Charcoal Properties 

What makes charcoal so amazing is the carbonisation process which creates a product with an enormous surface area to mass ratio, which has high ability to attract and hold (adsorption) a wide range of materials, chemicals, minerals, radio-waves, humidity, odours and harmful substances. As you can see from these images under a microscope, they have a number of pores. The porosity of activated carbon, as defined by IUPAC (International Union of Pure and Applied Chemistry), is divided in three families:

  • Macropores (> 250 Å);
  • Mesopores (10 ÷ 250 Å);
  • Micropores (< 10 Å).

Adsorption efficiency decreases over time and eventually activated carbon will need to go through a maintenance service of sieving, reactivation or replacement. 

Regular

Synthesizing single-crystalline hexagonal graphene quantum dots

A KAIST team has designed a novel strategy for synthesizing single-crystalline graphene quantum dots, which emit stable blue light. The research team confirmed that a display made of their synthesized graphene quantum dots successfully emitted blue light with stable electric pressure, reportedly resolving the long-standing challenges of blue light emission in manufactured displays. The study, led by Professor O Ok Park in the Department of Chemical and Biological Engineering, was featured online in Nano Letterson July 5.

Graphene has gained increased attention as a next-generation material for its heat and electrical conductivity as well as its transparency. However, single and multi-layered graphene have characteristics of a conductor so that it is difficult to apply into semiconductor. Only when downsized to the nanoscale, semiconductor’s distinct feature of bandgap will be exhibited to emit the light in the graphene. This illuminating featuring of dot is referred to as a graphene quantum dot.

Conventionally, single-crystalline graphene has been fabricated by chemical vapor deposition (CVD) on copper or nickel thin films, or by peeling graphite physically and chemically. However, graphene made via chemical vapor deposition is mainly used for large-surface transparent electrodes. Meanwhile, graphene made by chemical and physical peeling carries uneven size defects.

The research team explained that their graphene quantum dots exhibited a very stable single-phase reaction when they mixed amine and acetic acid with an aqueous solution of glucose. Then, they synthesized single-crystalline graphene quantum dots from the self-assembly of the reaction intermediate. In the course of fabrication, the team developed a new separation method at a low-temperature precipitation, which led to successfully creating a homogeneous nucleation of graphene quantum dots via a single-phase reaction.

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Magnetic &lsquo;springs&rsquo; break down ma…

Magnetic ‘springs’ break down marine microplastic pollution

Plastic waste that finds its way into oceans and rivers poses a global environmental threat with damaging health consequences for animals, humans, and ecosystems. Now, using tiny coil-shaped carbon-based magnets, researchers in Australia have developed a new approach to purging water sources of the microplastics that pollute them without harming nearby microorganisms. Their work appears July 31 in the journal Matter.

“Microplastics adsorb organic and metal contaminants as they travel through water and release these hazardous substances into aquatic organisms when eaten, causing them to accumulate all the way up the food chain” says senior author Shaobin Wang, a professor of chemical engineering at the University of Adelaide (Australia). “Carbon nanosprings are strong and stable enough to break these microplastics down into compounds that do not pose such a threat to the marine ecosystem.”

Although often invisible to the naked eye, microplastics are ubiquitous pollutants. Some, such as the exfoliating beads found in popular cosmetics, are simply too small to be filtered out during industrial water treatment. Others are produced indirectly, when larger debris like soda bottles or tires weather amid sun and sand.

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Leap toward robust binder-less metal phosphi…

Leap toward robust binder-less metal phosphide electrodes for Li-ion batteries

Researchers at the Toyohashi University of Technology have successfully fabricated a binder-less tin phosphide (Sn4P3)/carbon © composite film electrode for lithium-ion batteries via aerosol deposition. The Sn4P3/C particles were directly solidified on a metal substrate via impact consolidation, without applying a binder. Charging and discharging cycling stabilities were improved by both complexed carbon and controlled electrical potential window for lithium extraction. This finding could help realize advanced lithium-ion batteries of higher capacity.

Lithium-ion (Li-ion) batteries are widely used as a power source in portable electronic devices. They have recently attracted considerable attention because of their potential to be employed on a large-scale as a power source for electric vehicles and plugin hybrid electric vehicles, and as stationary energy storage systems for renewable energy. To realize advanced Li-ion batteries with higher energy density, anode materials with higher capacity are required. Although a few Li alloys such as Li-Si and Li-Sn, whose theoretical capacity is much higher than that of graphite (theoretical gravimetric capacity = 372 mAh/g), have been extensively studied, they generally result in poor cycling stability due to the large variation in volume during charging and discharging reactions.

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Atomically precise bottom-up synthesis of π-…

Atomically precise bottom-up synthesis of π-extended [5] triangulene

Chemists have predicted zigzag-edged triangular graphene molecules (ZTGMs) to host ferromagnetically coupled edge states, with net spin scaling with the molecular size. Such molecules can afford large spin tunability, which is crucial to engineer next-generation molecular spintronics. However, the scalable synthesis of large ZTGMs and the direct observation of their edge states are a long-standing challenge due to the high chemical instability of the molecule.

In a recent report on Science Advances, Jie Su and colleagues at the interdisciplinary departments of chemistry, advanced 2-D materials, physics and engineering developed bottom-up synthesis of π-extended [5]triangulene with atomic precision using surface-assisted cyclodehydrogenationof a molecular precursor on metallic surfaces. Using atomic force microscopy(AFM) measurements, Su et al. resolved the ZTGM-like skeleton containing 15 fused benzene rings. Then, using scanning tunneling spectroscopy (STM) measurements they revealed the edge-localized electronic states. Coupled with supporting density functional theory calculations, Su et al. showed that [5]triangulenes synthesized on gold [Au (111)] retained an open-shell π-conjugated character with magnetic ground states.

In synthetic organic chemistry, when triangular motifs are clipped along the zigzag orientation of graphene, scientists can create an entire family of zigzag-edged triangular graphene molecules. Such molecules are predicted to have multiple, unpaired π-electrons (Pi-electrons) and high-spin ground states with large net spin that scaled linearly with the number of carbon atoms of the zigzag edges. Scientists therefore consider ZTGMs as promising candidates for molecular spintronic devices.

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