As one of the remarkable chemicals, Graphene is needed for many researches and applications. Now let's see how Graphene is produced!
We will mention 5 types of production processes of Graphene. One of the methods of producing Graphene is exfoliation. As of 2014 exfoliation produced graphene with the lowest number of defects and highest electron mobility.
One example from exfoliation method can be given as adhesive tape. Andre Geim and Konstantin Novoselov initially used adhesive tape to split graphite into graphene. Achieving single layers typically requires multiple exfoliation steps, each producing a slice with fewer layers, until only one remains. After exfoliation the flakes are deposited on a silicon wafer. Crystallites larger than 1 mm and visible to the naked eye can be obtained.
Another production method is hydrothermal self-assembly. In this method Graphene has been prepared by using a sugar (e.g. glucose, fructose, etc.) This substrate-free "bottom-up" synthesis is safer, simpler and more environmentally friendly than exfoliation. The method can control thickness, ranging from monolayer to multilayers.
The third method in order to produce Graphene is epitaxy. Epitaxy refers to the deposition of a crystalline overlayer on a crystalline substrate. For this kind of method chemical vapor deposition can be given as example. Chemical vapor deposition (CVD) is a common form of epitaxy. The process of deposition of solid material onto a heated substrate through decomposition or chemical reaction of compounds contained in the gas passing over the substrate is called chemical vapor deposition. The reactants, generally in the gaseous or vapor phase, react on or near the surface of the substrates, which are at some elevated temperature. The subsequent reaction results in the deposition of atoms or molecules on the entire substrate surface.
Another method for producing Graphene is nanotube slicing. In this method Graphene can be created by cutting open carbon nanotubes. In one such method multi-walled carbon nanotubes are cut open in solution by action of potassium permanganate and sulfuric acid.
The other method in order to synthesize Graphene is microwave-assisted oxidation. In 2012, a microwave-assisted, scalable approach was reported to directly synthesize graphene with different size from graphite in one step. The resulting graphene does not need any post reduction treatment as it contains very little oxygen. This approach avoids use of potassium permanganate in the reaction mixture. It was also reported that by microwave radiation assistance, graphene oxide with or without holes can be synthesized by controlling microwave time. This method uses microwave heating. Microwave heating can dramatically shorten the reaction time from days to seconds.
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