Graphene : materials of the future ?

The last two lessons were devoted to a particularly topical research theme in materials science: graphene. Indeed, over the course of 2016, this subject has given rise to more than 25,000 publications and patents. This sharp increase in the scientific communities' interest in graphene in recent years is linked to several factors: its remarkable properties, the Nobel Prize in Physics awarded to André Geim and Konstantin Novoselov in 2010, its significant potential for applications, and the strong economic support from funding agencies and Europe in particular. To better understand the structure of graphene, we need only describe that of graphite, the black carbonaceous material used in pencil leads. Incidentally, the name "graphite" is derived from the Greek word graphein, meaning "to write". The structure of graphite is similar to that of a mille-feuille, with each layer made up of an infinite network of polycyclic aromatic hydrocarbons. Graphene corresponds to one of these sheets when isolated. It can therefore be defined either as a two-dimensional layer composed solely of carbon atoms arranged in a hexagonal, honeycomb-like pattern, or as the infinite-sized end member of the well-known aromatic cyclic hydrocarbon series: benzene (1 ring), naphthalene (2 rings), anthracene (3 rings), tetracene (4 rings), coronene (7 rings), ovalene (10 rings)... graphene (very large number of rings). By extension, the term "graphene" is often used to designate a variety of compositions ranging from monolayers of carbon atoms to a few layers (2 to 5). The number of graphene layers and their nature are often specified in the literature, and depending on the materials obtained, the terms "single-layer graphene", "multi-layer graphene", "graphene oxide" or "reduced graphene oxide" are used. All these designations define the main members of the graphene family.