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By Dr.Qian from Guizhou University of Finance and Eco | 16 July 2020 | 0 Comments

Graphene-the electronic material of the future!

What is graphene and its properties?
 
Graphene is a new type of nanomaterials with very stable structure, strong conductivity and thermal conductivity. It is recognized by scientists around the world as the most disruptive "king of new materials" and even known as the "black gold" in the field of materials. It has a load of applications and a bright future and is favored by many enterprises. Graphene can be used to make materials 200 times stronger than steel. It conducts heat and electricity better than copper.
 
What are the main advantages of graphene batteries?
 
Replacing lithium-ion batteries with graphene is a good idea because graphene batteries offer many advantages over existing batteries. Graphene batteries charge faster and last longer. The graphene ball material will increase the battery capacity by 45%. Charging speed is increased by 5 times. Typically, lithium-ion batteries take more than an hour to fully charge. However, graphene batteries can reduce this process to 12 minutes. In addition, while charging is faster, the aging process of these batteries won't be faster.
 
How to make graphene?
 
  1. Mechanical stripping
Mechanical stripping method is a method to obtain graphene thin layer materials by using the friction and relative motion between objects and graphene. This method is simple to operate and the resulting graphene usually maintains a complete crystal structure.
 
  1. REDOX process
The REDOX method is to use sulfuric acid, nitric acid and other chemical reagents and potassium permanganate, hydrogen peroxide and other oxidants to oxidize natural Graphite, increase the spacing between the Graphite layers, and insert Oxide between the layers to prepare Graphite Oxide. Then the reactants were washed in water and the cleaned solid was dried at low temperature to prepare graphite oxide powder. RGO was prepared by stripping graphite oxide powder by physical stripping, high temperature expansion and other methods. Finally, graphene oxide (RGO) was obtained by chemical reduction. This method is simple to operate, high yield, but low quality products. REDOX method uses sulfuric acid, nitric acid and other strong acids. There is a greater risk, and during the process it must use a lot of water for cleaning, with large environmental pollution.
Graphene prepared by oxidation-reduction method has abundant oxygen-containing functional groups and is easy to be modified. However, when graphene oxide is reduced, it is difficult to control the oxygen content of the reduced graphene. At the same time, graphene oxide will be continuously reduced under the influence of sunlight, high temperature in the carriage and other external influences. Therefore, the quality of all graphene products produced by the REDOX method is often inconsistent and difficult to control the quality.
3.Orientation appendage method
Germinal matrix orientation is attached to the body using atomic structure "of" out of graphene. First, let the carbon atoms penetrate into ruthenium under 1150 ℃, then cooling it to 850 ℃, then absorb  a large number of carbon atoms before will float to the surface of ruthenium, eventually the lens in the shape of a single layer of carbon atoms to complete a graphene layer. After the first layer is covered, the second layer begins to grow. The bottom layer of graphene strongly interacts with ruthenium. While the second layer is almost completely separated from ruthenium, it leaves only weak electrical coupling. However, the graphene sheets produced by this method are often of uneven thickness, and the adhesion between graphene and the substrate affects the properties of the carbon layer.
 
  1. Silicon carbide epitaxial method
 
SiC epitaxy method makes silicon atoms sublimate out of the material under ultra-high vacuum and high temperature environment, and the remaining C atoms are reconstructed in self-assembly form to obtain graphene based on SiC substrate. High quality graphene can be obtained by this method, but this method requires more equipment.
 
  1. HeMo method
 
Graphite oxide was prepared by Hummer method. Graphite oxide was dispersed by ultrasound in water to form a uniformly dispersed graphene oxide solution with a mass concentration of 0.25g/L ~ 1g/L. Ammonia water with a mass concentration of 28% was added to the graphene oxide solution. The reducing agent was dissolved in water to form an aqueous solution with a mass concentration of 0.25g/L ~ 2g/L. The prepared graphene oxide solution was mixed with an aqueous solution of reducing agent, and the resulting mixture was stirred in an oil bath. After the reaction, the mixture was filtered, washed and dried to obtain graphene.
 
  1. Chemical vapor deposition
Chemical vapor deposition (CVD) is a method for the preparation of graphene films by vapor deposition of organic gases containing carbon. This is currently the most efficient way to produce graphene films. The graphene prepared by this method has the characteristics of large area and high quality, but at present, the cost is high, and the process conditions need to be further improved. Due to the thin thickness of the graphene film, a large area of graphene film cannot be used alone, and it must be attached to the macro devices, such as touch screen, heater parts and so on.
 
  1. Low-pressure vapor deposition method
It is used by some scholars to generate monolayer graphene on Ir surface. Through further study, it can be known that this graphene structure can span metal steps, and continuous and micron-scale monolayer carbon structure can gradually form on Ir surface. Monocrystalline graphene at the millimeter scale was obtained by surface segregation. Cm magnitude of graphene and epitaxial growth on polycrystalline Ni thin film graphene is found by some scholars, when heated to 1000 ℃, 300 nanometers thick Ni membrane surface, at the same time in the atmosphere of CH4 in exposure, after after a period of reaction, a large area of a few layers of graphene films will be formed in the metal surface.
 
 
What is the graphene used for?
1.Drinking water:
Graphene can be used to distil brine and to make it drinkable. When seawater passes through the holes in the graphene, the lattice allows water molecules to pass through while blocking the atoms that form the salt.
 
2. Smart phones:
Graphene is both transparent and conductive, making it perfect for the next generation of smartphones.
 
3. The computer:
Graphene can replace silicon chips. Electronics companies are testing graphene in a number of electronic devices. IBM has experimented with computers using the material to reach a record speed of 100ghz.
 
4. Satellites and vehicles:
Its properties provide lightweight but super-strong composites for next-generation satellites, aircraft and cars. This can further reduce the weight of the aircraft, thereby reducing the burning of fuel.
 
5. Stainless car:
Graphene can be used in the field of waterproof, good electrical conductivity. This slows down the electrochemical reaction of iron oxide. Scientists have designed a graphene coating that can protect rusting steel for up to a month.
 
6. Defence transactions:
The graphene foam absorbs small amounts of nitrates and ammonia found in explosives.
 
7. Nuclear liquidation:
The tiny graphene oxide binds to a radioactive contaminant and converts it into a large extract.
 
TRUNNANO (Luoyang Trunnano Tech Co., Ltd ) is a professional Graphene manufacturer with over 12 years experience in chemical products research and development. If you are looking for high quality  Graphene, please feel free to contact us and send an inquiry.

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