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Many methods are used for nanoribbon production like, lithography, chemical reactions and ultrasoundinfluenced chemistry. But all these methods fail to produce the needed quantity or quality of graphene nanoribbons.
Fabrication processes
Researchers at Stanford University have developed a new method that will allow relatively precise production of mass quantities of the tiny ribbons by slicing open carbon nanotubes. The nanotube is to be opened up without destroying the whole structure. For this, carbon nanotubes are placed on a substrate and then coated with a polymer film. The film covers the entire surface of each nanotube, save for a thin strip where the nanotube is in contact with the substrate. The film is easily peeled off from the substrate, taking along all the nanotubes and exposing the thin strip of polymer free surface on each of them. A chemical etching process using plasma can then slice open each nanotube along that narrow strip. The process works not only on single-layer carbon nanotubes but also on nanotubes with concentric layers of nanotubes, allowing each layer to be sliced open. The ribbons can easily be removed from the polymer film and transferred onto any other substrate, making it easy to create items such as graphene transistors for making high-performance electronic devices and computer chips.
Researchers at Rice University have developed a room-temperature chemical process that splits, or unzips, carbon nanotubes to make flat nanoribbons. This technique makes it possible to produce the ultra thin ribbons in bulk quantities.
Sulfuric acid and potassium permanganate are used to attack single and multi walled carbon nanotubes, reacting with the carbon framework and unzipping them in a straight line. Nearly all of the nanotubes subjected to unzipping turn into graphene ribbons. But the multi walled nanotubes are much cheaper starting materials, and the resulting nanoribbons would be useful in a host of applications.
Engineers at University of Michigan have demonstrated that when a light was shone on flat nanoribbons, they curled up into spirals. The photons of light can lead to such a remarkable change in rigid structures a thousand times bigger than molecules, This spiral structure is very important for optics and could lead to the development of new materials.
Stanford chemists have developed a new way to make transistors out of carbon nanoribbons. The devices could be integrated into high-performance computer chips to increase their speed and generate less heat, which can damage silicon-based chips when transistors are packed together tightly.
University of California at Berkeley, US, has now used ab initio calculations to show that certain carbon nanoribbons will display half-metallicity, Researchers have predicted that a small ribbon made of the carbon honeycomb pattern found in graphite and nanotubes could display intriguing electronic properties and serve as a material for spin-based electronics (spintronics),
Nanoribbons are strong, thermally and electrically conductive and have a very large aspect ratio. This material is amorphous as it has little long-range atomic order. As a result the surface chemistry is more closely related to Diamond-like Carbon and Carbon Blacks, making nanoribbons much more easy to disperse in most media. The fibres are flat in cross-section, with an average fibre measuring 30nm wide by ca.2nm thick by 100’s of microns long (up to 1mm). Material is commercially supplied as a highly porous black powder. See : www.nano-tek.co.uk/
Applications of Nano-ribbons
• Multi-functional composites
• Biosensors
• Catalyst support
• Electrodes
• Lubricant additive
Potential applications of nanoribbon coatings
• Catalysis
• Sensors
• Electrodes
Available forms
Nano-Ribbons are also available as a homogeneous coating on substrates such as Quartz, Si-wafer, 316 and 440c stainless foils and plate. The majority of the nano-fibres show some alignment perpendicular to the plane of the substrate CostNano-Ribbons of purity ca. 99.9% C, SSA ca. 300m2g-1 has a price of £80 to 350/ g.

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