Introduction to Graphene

Graphene is a new material 1 a single-layer sheet structure composed of carbon atoms. It is the 1 two-dimensional material composed of carbon atoms with sp2 hybrid orbitals in a hexagonal honeycomb lattice and only one carbon atom thick. Graphene has always been considered to be a hypothetical structure and cannot exist stably alone. Until 2004, physicists Andre Heim and Konstantin Novoselov of the University of Manchester in the United Kingdom successfully separated graphene from graphite in the experiment and confirmed that it can exist alone. The two also won the 2010 Nobel Prize in Physics for "pioneering experiments on two-dimensional graphene materials.

Graphene is the thinnest but hardest nanomaterial in the world. It is almost completely transparent and only absorbs 2.3 percent of light. The thermal conductivity is as high as 5300 w/m k, which is higher than that of carbon nanotubes and diamond. Its electron mobility * exceeds 15000cm/v s at normal temperature, which is higher than that of carbon nanotubes or silicon crystals *, and its resistivity is only about 10-6 Ω · cm, lower than copper or silver, the world's smallest resistivity material. Because of its extremely low resistivity and extremely fast electron migration, it is expected to be used to develop a new generation of electronic components or transistors with thinner and faster conductivity. Because graphene is essentially the 1 kind of transparent and good conductor, it is also suitable for manufacturing transparent touch screens, light panels, and even solar cells.

Another feature of graphene is that the quantum Hall effect can be observed at room temperature.

The arrangement of carbon atoms in graphene is similar to that of single atomic layer of graphite. It is a single layer two-dimensional crystal composed of carbon atoms arranged in a honeycomb lattice (honeycomb crystal lattice) with SP2 mixed orbital domain. Graphene can be imagined as an atom-sized network formed by carbon atoms and their covalent bonds. The name of graphene comes from the English graphite (graphite) + -ene (ene ending). Graphene is considered to be a planar polycyclic aromatic hydrocarbon atomic crystal.

The structure of graphene is very stable, with carbon-carbon bonds (carbon-carbonbond) of only 1.42 Å. The connection between the carbon atoms inside the graphene is very flexible. When an external force is applied to the graphene, the carbon atom surface will bend and deform, so that the carbon atoms do not have to be rearranged to adapt to the external force, thereby maintaining the stability of the structure. This stable lattice structure gives graphene excellent thermal conductivity.

Graphene is the basic unit that constitutes the following carbon allotropes: graphite, charcoal, carbon nanotubes and fullerenes. Perfect graphene is two-dimensional, it only includes hexagons (equiangular hexagons); if there are pentagons and heptagons, it will constitute a defect of graphene. The 12 pentagonal graphenes will together form fullerenes.

Graphene rolled into a barrel can be used as carbon nanotubes; in addition, graphene is also made into ballistic transistors (ballistic transistor) and has attracted the interest of a large number of scientists. In March 2006, Georgia Institute of Technology researchers announced that they successfully fabricated graphene planar field effect transistors, and observed the quantum interference effect, and based on this result, developed a graphene-based circuit.

The advent of graphene has caused a worldwide research boom. It is the thinnest 1 of the known materials. The material is very strong and hard. At room temperature, it transfers electrons faster than known conductors. The atomic-size structure of graphene is so special that it must be described by quantum field theory.

Graphene is 1 kind of two-dimensional crystal, the common graphite is formed by stacking layers of planar carbon atoms arranged in a honeycomb shape, the interlayer force of graphite is weak, it is easy to peel off each other, forming a thin graphite sheet. When the graphite sheet is peeled into a single layer, this single layer, which is only one carbon atom thick, is graphene. A brief history of development. First: graphene is the strongest material in the world. It is estimated that if graphene is made into a film with a thickness equivalent to that of ordinary food plastic packaging bags (about 100 nanometers in thickness), it will be able to withstand the pressure of about two tons of heavy goods without breaking. Second: graphene is the most conductive material in the world.

Graphene has a wide range of applications. According to the ultra-thin and super-strong characteristics of graphene, graphene can be widely used in various fields, such as ultra-light body armor, ultra-thin and ultra-light aircraft materials. According to its excellent conductivity, it also has great application potential in the field of microelectronics. Graphene may become a substitute for silicon, making ultra-miniature transistors to produce future supercomputers. The higher electron mobility of carbon elements can enable future computers to obtain higher speeds. In addition, graphene materials are also 1 excellent modifiers, and in new energy fields such as supercapacitors and lithium-ion batteries, due to their high conductivity and high specific surface area, they can be used as electrode material additives.