Graphene, an allotrope form of carbon which consists a single layer of carbon, which atoms arranged in an hexagonal lattice. It is a basic and auxiliary component of numerous other allotropes of carbon such as graphite, charcoal, fullerenes and carbon nanotubes. Graphene can be imaged as an aromatic molecule with indefinitely size.
Numerous surprising properties are found in graphene. For instance, graphene is the most strongest material among ever tested, with nearly transparent efficiently conducts heat and electricity. Graphene demonstrates a huge and nonlinear diamagnetism, which is more prominent than the diamagnetism of graphite, and can be suspended by neodymium magnets.
Wallace firstly explored graphene as a starting point in research to understand 3D graphite especially the electronic characteristics in 1947. Producing monolayer flakes of reduced graphene oxide was reported by Boehm in 1962. Since 2004 Geim and Novoselov extracted single-atom-thick crystallites from bulk graphite. Therefore Geim and Novoselov received 2010 Nobel Prize in Physics for their pioneering research of graphene.
Graphene is one of allotrope of carbon in crystalline state with 2-dimensional properties. Carbon atoms in graphene are densely packed in the form of a regular hexagonal pattern. It has various excellent properties, including area of electronic, thermal, mechanical and optical. First of all, the specific surface area of graphene is up to 2630 , which is larger than normal carbon and carbon nanotubes. Besides, graphene is the strongest material among ever tests which makes graphene has a good characteristic of mechanical. What’s more, the thermal conductivity measured of graphene is approximately 5300 , which is much larger than what of pyrolytic graphite of nearly 2000 at room temperature. In the end, the properties of graphene of optical is unique, because of the produce of an high opacity for an atomic monolayer in vacuum unexpectedly.
Graphene can be used in variety of aspects of life, one typical example is the usage of transistors. On the one hand, the excellent mobility of graphene is its most compelling feature. On the other hand, it may be possible to making devices with extremely thin channels which will give graphene more possibility to field-effect transistors to be scaled to shorter channel lengths and higher speeds without be encountered with the adverse short-channel effects which restrict the performance of existing devices. In the future, more Metal-Oxide-Semiconductor Field-Effect Transistor(MOSFET) can be settled in the same size of the Central Processing Unit(CPU) because of the technical of graphene transistor. Besides, some other applications should be paid attention such as graphene-based sensor and graphene-based hydrogen storage, which are the usage of graphene to give sensor or hydrogen storage higher performance. In spite of electronic applications, graphene is also reported to improve the color of photonics crystals in optical devices.
There are several preparation method of graphene, since 2014, graphene produced by exfoliation has the highest electron mobility and lowest number of defects. Geim and Novoselov firstly used adhesive tape to get graphene sheets from graphite, then single layers can achieved with multiple exfoliation steps. After exfoliation they deposited the flakes on a silicon wafer. Finally a sharp single-crystal diamond wedge cleave layers from a graphite source alternatively. Another method to produce graphene is reduction of graphite oxide monolayer films, which in divided in four steps, including oxidation of graphite to graphite oxide, exfoliation of graphite oxide in H2O by sonication to obtain GO colloids and controlled conversion of GO colloids to conducting graphene colloids through deoxygenation by hydrazine reduction.
Since the theory introduced by Wallace in 1947, the graphene has been researched to various aspects. Its excellence properties in many aspects makes it much useful in different areas and beneficial to human’s life in future. According to the latest research, graphene can be used as a transparent and flexible conductor to achieve various material applications, including solar cells, LED, touch sensors and smart cell phones. For example, the produce of graphene transistors can improve the performance of the mobile electrical devices like cell phones with the decrease of the power supply.
In addition to the various application, there will be over $9 million of the global market for graphene in the aspects of the semiconductor, battery, electronics, energy storage and conversion, which will brings uncountable value of business in future.