ABSTRACT
Graphene is considered today the most amazing and versatile substance available to mankind, and since its discovery in 2004, it is without any doubt the most intensively studied material [1,2]. From a chemical point of view, it is constituted by a single atomic layer of sp2-hybridized carbon atoms, with a molecule bond length of 0.142 nm tightly packed in a 2D honeycomb lattice (Figure 21.1). Because of its chemical structure, this material is the thinnest compound known. Although it is just one atom thick, graphene possesses outstanding mechanical, electronic, optical, thermal, and chemical properties (Table 21.1) [3-9]. Graphene is mechanically very strong and ‰exible. The breaking strength of graphene is more than 100 times greater than that of steel [4]. Besides its extraordinary strength, graphene is also very light, with 0.77 mg/m2. Its crystal structure does not break even after being stretched up to 20% [5]. Moreover, this material has shown to be the best conductor of heat and electricity [6,7]. From an electrical aspect, the carrier mobility of graphene at room temperature is more than 100 times higher than that of silicon [6]. Its thermal conductivity, measured at room temperature, is much higher than the value observed in all the other carbon structures as carbon nanotubes, graphite, and diamond and is 10 times higher than Cu [7]. Furthermore, graphene is an ultra-wideband optical material that interacts strongly with light of a wide range of wavelengths; it absorbs ~2.3% of light in the visible to infrared region, and this absorption coef cient is one to three orders of magnitude higher than those of conventional semiconductor materials [9].
