Graphene

Graphene is a one atom thick, two-dimensional material consisting of carbon atoms arranged in a honeycomb-like structure.  This is known as a single-layer graphene.  Bi-layer and multi-layer graphenes have also been synthesized in the laboratory. If you stack enough graphene layers together, you will make a graphite crystal.

Graphene exhibits very interesting electrical, optical, mechanical, and thermal properties.  Electrically, it is a semimetal or a semiconductor with zero bandgap.  Graphene shows a very low resistivity, for example, only 10^-6 Wcm at room temperature.  A single layer graphene film is fairly transparent and absorbs only 2% of the light incident on it.  The mechanical properties are exceptional; for example, its Young’s modulus is about 2 TPa (TPa = one trillion or 10¹² Pascal). For comparison, steel has a Young’s modulus of about 0.2 TPa

The interesting properties of graphene have led to an explosion of research recently focused on its synthesis, characterization, and development for a variety applications.  Promising applications include electronics devices, transparent conducting electrodes for solar cells and plasma displays, composite materials, energy storage devices, and chemical and biological sensors. 

Currently researchers are able to produce graphene by reducing graphene oxide.  This chemical synthesis approach can now yield gram quantities of the material.  It is also possible to deposit a single layer of graphene on a silicon wafer.  A technique called chemical vapor deposition allows growth of single or multilayer graphene at 900-1000 ºC.