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graphene boron stacks lo res

Published on February 20th, 2014 | By: April Gocha, PhD

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A graphene sequel (Spoiler: molecular sieves, atomic layer films, the origins of life, antithrombotic films, and artificial graphene inside)

Published on February 20th, 2014 | By: April Gocha, PhD

I reported on Monday about some really impressive advances for the synthesis of graphene nanoribbons that allow electrons to reach ballistic transport. But when it comes to graphene, there’s so much more than electron conduction—graphene has recently made an appearance in a dizzying array of research fields. What follows is a sampling of graphene’s other talents.

 

A report in Science last week detailed the use of graphene oxide membranes for molecular sieves. The University of Manchester scientists synthesized thin laminates of stacked hydrophobic graphene oxide layers that, when immersed in water, allow rapid permeation of water molecules and small ions (<0.45 nm) through nanocapillaries that form on the film surface. The membrane blocks larger solutes from passing through.

Rahul-Membrane lo res

Rahul Nair holds a thin graphene membrane that functions as an efficient molecular sieve. Credit: University of Manchester.

 

“The water filtration is as fast and as precise as one could possibly hope for such narrow capillaries,” Rahul Nair (pictured left), senior author of the study, said in a press release. “Now we want to control the graphene mesh size and reduce it below 9 Å to filter out even the smallest salts like in seawater. Our work shows that it is possible.”

 

The team is now working with a few companies to explore possible uses of graphene oxide membranes in molecular separation, water filtration, and barrier coating for packaging applications, Nair said in an email. The paper is “Precise and Ultrafast Molecular Sieving Through Graphene Oxide Membranes” (DOI: 10.1126/science.1245711).

 

Another report in Nature Communications details a process that “systematically converts the hexagonal carbon lattice of graphene to boron nitride, making it possible to produce uniform boron nitride and boron carbonitride structures without disrupting the structural integrity of the original grapheme templates,” according to the paper’s abstract. Fabrication of thin integrated circuits is the potential application. The easy transition would allow circuits to be built from graphene, boron nitride, and boron carbonitride, allowing fine-tuning for conductor, semiconductor, and insulator properties within thin integrated circuits. That paper is “Direct Chemical Conversion of Graphene to Boron- and Nitrogen- and Carbon-Containing Atomic Layers” (DOI: 10.1038/ncomms4193).

 

And digressing from our planetary material desires, graphene is also popping up in astronomy as a means to understand the origins of life. Like I said, graphene is big—now, it’s graduated to origins of life big.

 

Again in Nature Communications, this recent report highlights how graphene can form on the surface of silicon carbide (SiC) in conditions mimicking those of space. Graphene falls into the group of polycyclic aromatic hydrocarbons, which are incredibly prevalent in interstellar space, and may be able to explain how organic molecules first appeared. The paper is “Graphene Etching on SiC Grains as a Path to Interstellar Polycyclic Aromatic Hydrocarbons Formation” (DOI: 10.1038/ncomms4054).

 

I wonder if graphene would be next to appear on the TV show PitchMen? But wait, there’s more!…

 

Another Nature Communications report published this week describes the potential use of graphene films on the surface of biomedical implants to prevent blood clots, which are prone to occur at the interface between an implanted biomedical device and blood. The authors exploited graphene’s surface properties, particularly its vast surface area and biocompatibility, to make graphene support substrates for hemin and glucose oxidase. Both are catalysts for a sequence of reactions that eventually generate nitric oxide, a known antiplatelet agent.

 

While previous approaches to harness the power of nitric oxide have focused on exogenous applications, this novel approach is more efficient because the enzymes can be used to catalyze endogenous generation of nitric oxide within the patient, at the site where the molecules are needed most. The paper is “Integration of Molecular and Enzymatic Catalysts on Graphene for Biomimetic Generation of Antithrombotic Species” (DOI: 10.1038/ncomms4200).

 

And finally, a report published last Friday in Physical Review X detailed the generation of nanometer-thick sheets of semiconductor crystals arranged in the familiar honeycomb structure—faux graphene. According to a press release from University of Luxembourg, one of the collaborating institutions on the project, this advance may “cause a technological revolution,” by vastly improving the size, weight, and performance of electronic and optical devices, “including higher performance photovoltaic cells, lasers, or LED lighting.”

 


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