Physicochemical properties of few-layer graphene

Few-layer graphene overview

Few-layer graphene refers to the type of 3-10 layers of carbon atoms that are periodically and tightly packed into a benzene ring structure (ie, a hexagonal honeycomb structure) and stacked in different stacking methods (including ABC stacking, ABA stacking, etc.). ) two-dimensional carbon materials.

A new type of carbonaceous material with two-dimensional structure of single-layer graphene powder. Graphene powder has excellent electrical, thermal and mechanical properties.

Physicochemical properties of few-layer graphene

physical properties

The arrangement of carbon atoms in graphene is the same as that of the single atomic layer of graphite to form bonds with sp2 hybrid orbitals, and has the following characteristics: carbon atoms have 4 valence electrons, of which 3 electrons generate sp2 bonds, that is, each carbon atom has a sp2 bond. By donating an unbonded electron located on the pz orbital, the pz orbital of the neighboring atom is perpendicular to the plane to form a π bond, and the newly formed π bond is in a half-filled state. The study confirmed that the coordination number of carbon atoms in graphene is 3, the bond length between every two adjacent carbon atoms is 1.42 × 10-10 meters, and the angle between the bonds is 120°. In addition to the honeycomb layered structure in which σ bonds link with other carbon atoms to form hexagonal rings, the pz orbitals of each carbon atom perpendicular to the layer plane can form large π bonds (similar to benzene rings) of polyatoms throughout the entire layer, Therefore, it has excellent electrical conductivity and optical properties.

chemical properties

The chemical properties of graphene are similar to graphite, and graphene can adsorb and desorb various atoms and molecules. When these atoms or molecules act as donors or acceptors, the graphene carrier concentration can be changed, while graphene itself can maintain good electrical conductivity. But when other substances are adsorbed, such as H+ and OH-, some derivatives are produced that make graphene less conductive, but no new compounds are produced. Therefore, the properties of graphene can be inferred using graphite. For example, the generation of graphane is based on two-dimensional graphene, adding one more hydrogen atom to each carbon atom, so that the sp2 carbon atoms in graphene become sp3 hybridization. Soluble fragments of graphene that can be prepared in the laboratory from chemically modified graphite.

Few-layer graphene applications

With the gradual breakthrough of mass production and large-scale problems, the industrial application of graphene is accelerating. Based on existing research results, the first commercial applications may be mobile devices, aerospace and new energy. battery field. Graphene has special significance in fundamental research in physics. It enables some quantum effects that were previously only demonstrated theoretically to be experimentally verified. In 2D graphene, the mass of electrons does not seem to exist. This property makes graphene a rare condensed matter 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, giving theoretical physicists a way to New research direction: Some experiments that would otherwise have to be done in giant particle accelerators can be done in small labs with graphene. The zero-gap semiconductor is mainly single-layer graphene, and this electronic structure can seriously affect the action of gas molecules on its surface. The results of graphene hydrogenation and oxidation reactions demonstrate the enhanced surface activity of monolayer graphene compared to bulk graphite, suggesting that the electronic structure of graphene can tune its surface activity. In addition, through the induction of gas molecule adsorption, the electronic structure of graphene can be changed accordingly, not only changing the carrier concentration, but also doping different graphenes.

1. Sensors

Graphene can be made into chemical sensors. This process is mainly accomplished by the surface adsorption properties of graphene. According to the research of some scholars, the sensitivity of 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, the transistor can still work stably at the scale of a single atom. In contrast, current silicon-based transistors lose their stability on a scale of about 10 nanometers; the ultra-fast reaction rate of electrons in graphene to external fields allows transistors made from it to reach very high operating frequencies. For example, IBM announced in February 2010 that it would increase the operating frequency of graphene transistors to 100GHz, i.e. exceeding silicon transistors of the same size.

3. Flexible display

At the Consumer Electronics Show, flexible screens have attracted much attention and become the development trend of future mobile device displays. The future market of flexible displays is broad, and the prospect of graphene-based materials is also very broad. For the first time, South Korean researchers have produced a flexible transparent display composed of a multilayer graphene and glass fiber polyester sheet substrate. Researchers at Samsung and Sungkyunkwan University in South Korea have fabricated a piece of pure graphene the size of a TV on a 63-centimeter-wide flexible, transparent glass-fiber polyester sheet. They say this is the largest "bulk" graphene block to date. They then used the graphene blocks to create a flexible touchscreen. The researchers say that, in theory,

4. New energy battery

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

5. 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 channel in the graphene film is further compressed by mechanical means, the pore size is controlled, and the salt in seawater is effectively filtered.

6. Hydrogen storage materials

Graphene has the advantages of light weight, high chemical stability, and large specific surface area, and is the best candidate for hydrogen storage materials.

7. Aerospace

Due to the characteristics of high conductivity, high strength, and ultra-thinness, graphene has outstanding application advantages in aerospace and military industries. In 2014, NASA developed a graphene sensor for aerospace applications that can detect trace elements in the high-altitude atmosphere and structural defects on spacecraft. Graphene will also play a more important role in potential applications such as ultralight aircraft materials.

8. Photosensitive element

A new type of photosensitive element using graphene as a photosensitive element material is expected to have a special structure with thousands of times higher sensitivity than existing CMOS or CCD, while the energy consumption is only 10% of the original. It can be used in the field of monitors and satellite imaging, and can be used in cameras, smartphones, etc. arrive

9. Composites

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

10. Biology

Graphene is used to accelerate the osteogenic differentiation of human bone marrow mesenchymal stem cells and also to fabricate epitaxial graphene biosensors on silicon carbide. At the same time, graphene can be used as a neural interface electrode without changing or destroying properties such as signal strength or scar tissue formation. Graphene electrodes are more stable in vivo than tungsten or silicon electrodes due to their flexibility, biocompatibility, and electrical conductivity. Graphene oxide is very effective in inhibiting the growth of E. coli without harming human cells.

The price of few-layer graphene

The price of few-layer graphene will change randomly with the production cost, transportation cost, international situation, exchange rate, and the supply and demand of the few-layer graphene market. Tanki New Materials Co., Ltd. aims to help industries and chemical wholesalers find high-quality, low-cost nanomaterials and chemicals by providing a full range of customized services. If you are looking for multi-layer graphene, please feel free to send an inquiry to get the latest price of multi-layer graphene.

Few-layer graphene suppliers

As a global supplier of few-layer graphene, Tanki New Materials 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.

single layer graphene

Monolayer graphene purity::>99.3wt%

Single-layer graphene single-layer rate: 97%

Single-layer graphene thickness: 0.55nm-1.2nm

Single-layer graphene diameter: 1μm-12μm

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

Monolayer Graphene Color: Black

Single-layer graphene conductivity: 1000-1500 S/M

Single-layer graphene product COA: C=99.6%, O<0.4%