Graphene, the most amazing material in the world

In 2004, a new material with strange properties was discovered. It is a two-dimensional hexagonal lattice structure composed of carbon atoms with a single atomic layer or atomic layer thickness. Graphene has a unique electronic energy band structure and relativistic electronics. It is the most ideal two-dimensional electronic system discovered so far, with rich and novel physical properties.

Graphene is a new type of carbon material that has a two-dimensional honeycomb lattice structure and is densely packed by a single layer of carbon atoms. It is the basic unit for constructing carbon materials of other sizes. Graphene is a hexagonal honeycomb crystal formed by hybrid carbon atoms, and its thickness is only a single layer of atoms. Graphene is a two-dimensional structure, but in fact it is not flat, but wavy. Each carbon atom in graphene is connected to three surrounding carbon atoms through a special single bond. The remaining electrons can move freely, so graphene can conduct electricity. To some extent, it can be considered that the entire graphene sheet forms a large x bond.

Graphene preparation

 1) Tear tape method/micro friction method

The most common method is micromechanical separation, which can cut graphene sheets directly from larger crystals. The typical preparation method is friction with pyrolytic graphite, which will expand or introduce defects due to another material. The surface of massive graphite produces flocculated crystals, which contain single-layer graphene.

2) Epitaxial growth on the surface of silicon carbide

The method is to remove silicon by heating single crystal silicon carbide and decompose graphene sheets on the surface of the single crystal. The bulk process is to remove oxides by heating the sample under high vacuum by electron bombardment after oxygen or hydrogen etching. Use Auger electron spectroscopy (AES) to confirm that the oxide on the surface has been completely removed. The sample is heated to 1250-1450°C and then kept at a constant temperature for 1 minute and 20 minutes to form a very thin graphite layer.

3) The hydrazine reduction method will

The graphene oxide paper is placed in a pure hydrazine solution (a compound of hydrogen and nitrogen atoms) to reduce the graphene oxide paper to a single-layer graphene.

4) Pyrolysis of sodium ethoxide

First, the ethanol is reduced with nano metal, then the ethoxide product is cracked, and washed with water to remove the sodium salt. Obtain graphene adhesion. Then, kilograms of pure graphene can be prepared by vibration dispersion using soft sound waves.

5) Cutting carbon nanotubes

Cutting carbon nanotubes is also an experimental method for making graphene ribbons. One method is to use potassium permanganate and sulfuric acid to cut multi-walled carbon nanotubes in a solution. Another method uses plasma etching to etch nanotubes partially embedded in polymers.

 Characteristics of Graphite

 Not only is it the thinnest material known, but it is also very strong and rigid. As a simple substance, its electron transport speed at room temperature is faster than that of known conductors.

The connections between carbon atoms in graphene are very flexible. When an external force is applied, the surface of the carbon atoms will bend and deform, so there is no need to rearrange the carbon atoms to adapt to the external force, thereby maintaining structural stability.

This stable lattice structure makes carbon atoms have excellent electrical conductivity. When the electrons in graphene move in orbits, they will not be scattered due to lattice defects or the introduction of foreign atoms. Because the force between atoms is very strong at room temperature, even if the surrounding carbon atoms collide, the electronic interference in graphene is very small. This gives it unique advantages in the application of transparent conductive films, which are very important in the field of liquid crystal displays and solar cells. In addition, graphene has shown attractive application prospects in high-sensitivity sensors and high-performance energy storage devices.

The biggest feature of graphene is that the speed of electrons in graphene reaches 1/300 of the speed of light, which is much faster than electrons in ordinary conductors. This makes the electrons in graphene or more accurately called "loaders," whose properties are very similar to relativistic neutrinos. In addition, the study also found that graphene has considerable opacity, despite the original thickness of a single layer: it can absorb about 2.3 times.

Graphene overview

Few-layer graphene refers to a type composed of 3-10 layers of carbon atoms. These carbon atoms are periodically and closely packed in a benzene ring structure (ie, hexagonal honeycomb) stacked in different stacking methods (including ABC stacking, ABA stacking, etc.) Structure). Two-dimensional carbon material

Single-layer graphene powder has a two-dimensional structure of a new type of carbon material, and graphene powder has excellent electrical, thermal and mechanical properties.

The single-layer graphene powder produced by our company has a very large surface area, 500~1200m2/g.

Single layer graphene

Single-layer graphene purity:> 99.3wt%

Single-layer graphene single-layer ratio: 97%

Single layer graphene thickness: 0.55nm-1.2nm

Single layer graphene diameter: 1μm-12μm

Single-layer graphene specific surface area: 500-1200m2 / g

Single-layer graphene color: black

Single layer graphene conductivity: 1000-1500 S / M

COA of single-layer graphene products: C = 99.6%, O <0.4%

Graphene applications

With the gradual breakthrough of large-scale production and large-scale problems, the industrial application of graphene is accelerating. Based on the results of existing research, the first commercial applications may be mobile devices, aerospace and new energy. Battery field. Graphene has special significance for the basic research of physics. It can realize some quantum effects that can only be proved theoretically, and then can be verified through experiments. In two-dimensional graphene, electronic mass does not seem to exist. Making graphene a rare condensate that can be used to study relativistic quantum mechanics-because massless particles must move at the speed of light, they must be described by relativistic quantum mechanics, which provides theoretical physicists with new research directions: In the laboratory, graphene can be used to carry out some experiments that originally needed to be carried out in a giant particle accelerator. Zero energy gap semiconductors are mainly single-layer graphene, and this electronic structure will seriously affect the role of gas molecules on its surface. The results of graphene hydrogenation and oxidation reactions prove that single-layer graphene has the function of enhanced surface reactivity compared with bulk graphite, indicating that the electronic structure of graphene can adjust its surface activity. In addition, the electronic structure of graphene can be changed accordingly by inducing the adsorption of gas molecules, which not only changes the concentration of carriers, but also can be doped with different graphenes.

1. Sensor

Graphene can be made into chemical sensors. This process is mainly completed by the surface adsorption characteristics of graphene. According to the research of some scholars, the sensitivity of the graphene chemical detector can be compared with the limit of single molecule detection. The unique two-dimensional structure of graphene makes it very sensitive to the surrounding environment. Graphene is an ideal material for electrochemical biosensors. Sensors made of graphene have good sensitivity for detecting dopamine and glucose in drugs.

2. Transistor

Graphene can be used to make transistors. Due to the high stability of the graphene structure, this type of transistor can still work stably on the scale of a single atom. On the contrary, current silicon-based transistors will lose stability in scale. About 10 nanometers; the ultra-fast reaction speed of the electrons in graphene to the external field enables transistors made of it to reach high operating frequencies. For example, IBM announced in February 2010 that it would increase the operating frequency of graphene transistors to 100 GHz, surpassing silicon transistors of the same size.

3. Flexible display

At the Consumer Electronics Show, flexible screens have attracted widespread attention and become the development trend of mobile device displays in the future. The future market for flexible displays is broad, and graphene has a bright future as a basic material. South Korean researchers have produced for the first time a flexible transparent display composed of multilayer graphene and a glass fiber polyester sheet substrate. Researchers from Samsung and Sungkyunkwan University in South Korea fabricated a piece of pure graphene the size of a TV on a 63 cm wide flexible transparent glass fiber polyester board. They say this is the largest "bulk" graphene block to date. Subsequently, they used graphene blocks to create a flexible touch screen. The researchers said that, theoretically,

4. New energy battery

New energy batteries are also an important field for the earliest commercial applications of graphene. The Massachusetts Institute of Technology in the United States has successfully developed a flexible photovoltaic panel with graphene nano-coating on the surface, which can greatly reduce the cost of manufacturing transparent and deformable solar energy. The battery can be used in night vision goggles, cameras and other small digital devices. In addition, the successful development of graphene super batteries has also solved the problem of insufficient capacity and long charging time for new energy vehicles, which has greatly promoted the development of the new energy battery industry. The application of graphene in the new energy battery industry.

5. Seawater desalination

Graphene filters are used more than other desalination technologies. After the graphene oxide film in the water environment is in close contact with water, a channel with a width of about 0.9 nanometers can be formed, and ions or molecules smaller than this size can pass through quickly. The size of the capillary channels in the graphene film is further compressed by mechanical means, and the pore size is controlled, which can effectively filter the salt in the seawater.

6. Hydrogen storage materials

Graphene has the advantages of light weight, high chemical stability and high specific surface area, making it the best choice for hydrogen storage materials.

7. Aerospace

Due to its high conductivity, high strength, ultra-light and thin characteristics, graphene's application advantages in aerospace and military industries are also very prominent. In 2014, the National Aeronautics and Space Administration (NASA) developed a graphene sensor for aerospace applications that can detect trace elements in the high-altitude atmosphere and structural defects of spacecraft. Graphene will also play a more important role in potential applications such as ultralight aircraft materials.

8, photosensitive element

The new photosensitive element using graphene as the photosensitive material is expected to have a special structure. Compared with the existing CMOS or CCD, its sensitivity is increased by thousands of times, and the energy consumption is only 10% of the original. It can be used in surveillance and satellite imaging fields, and can be used in cameras, smart phones, etc. To

9. Composite materials

Graphene-based composite materials are an important research direction in the application of graphene. They have excellent performance in the fields of energy storage, liquid crystal devices, electronic devices, biological materials, sensor materials and catalyst carriers, and have broad application prospects. At present, the research of graphene composite materials mainly focuses on graphene polymer composite materials and graphene-based inorganic nanocomposite materials. With the continuous deepening of graphene research, the application of graphene-enhanced materials in metal matrix composites has attracted more and more attention. Multifunctional polymer composite materials and high-strength porous ceramic materials made of graphene enhance many special properties of composite materials.

10. Biology

Graphene can be used to accelerate the osteogenic differentiation of human bone marrow mesenchymal stem cells, and it can also be used to fabricate epitaxial graphene biosensors on silicon carbide. At the same time, graphene can be used as a nerve interface electrode without changing or destroying properties. Due to its flexibility, biocompatibility and conductivity, graphene electrodes are much more stable in vivo than tungsten or silicon electrodes. Graphene oxide is very effective in inhibiting the growth of E. coli without damaging human cells.

Graphene price

China also has unique advantages in graphene research. From a production point of view, graphite is the raw material for graphene production and has abundant energy storage and low prices in my country. It happens to see that many countries have established the application prospects of graphene. The graphene-related technology research and development center tries to commercialize graphene and then obtains patents for potential applications in industry, technology, and electronics-related fields. For example, the European Commission has formulated a special graphene research and development plan as the focus of graphene research and development. "Future Emerging Flagship Technology Project", and allocate 1 billion euros in the next 10 years. The British government has also invested in the establishment of the National Graphene Institute (NGI), with a view to using this material from the laboratory for production lines and markets in the next few decades.

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Graphene suppliers

As a global supplier of a few layers of graphene, Tanki New Materials Co., Ltd. has extensive experience in the performance, application and cost-effective manufacturing of advanced and engineered materials. The company has successfully developed a series of powder materials (including oxides, carbides, nitrides, single metals, etc.), high-purity targets, functional ceramics and structural devices, and provides OEM services.