13. Characterization of Nanocarbons: From Graphene to Graphene Nanoribbons (GNRs) and Quantum Dots (GQDs)

Recent progress in the synthesis of carbon nanostructures has triggered a large number of studies aiming to elucidate their fundamental properties and to pave their way to possible applications. The successful isolation of single graphite sheets, called graphene (Geim and Novoselov Nat Mater 6:183–191, 2007), has attracted worldwide attention due to its exceptional and unique charge transport and thermal, optical, and mechanical properties. Graphene and its derivatives are being studied in nearly every field of science and engineering (Singh et al. Prog Mater Sci 56:1178–1271, 2011). Recent progress has shown that graphene nanoribbons – narrow- and straight-edged stripes of graphene – exhibit special electronic properties that make them attractive for the fabrication of nanoscale electronic device due to their sizeable bandgap which overcomes many of the limitations of graphene (Cai et al. Nature 466:470–473, 2010). Due to their outstanding properties, graphene and GNRs can be potentially applied in several research areas such as high-frequency analog circuits; spintronic, nanoelectronic, chemical, and biological sensing; energy storage; and switching devices (Cai et al. Nature 466:470–473, 2010; Biro et al. Nanoscale 4:1824–1839,2012; Cai et al. Nat Nanotechnol 9:896–900, 2014). Characterization techniques play a fundamental role in graphene and graphene-based material research, since these allow the detailed knowledge about the number of layers of graphene; the width, length, and distribution of GNRs; the purity and homogeneity of the sample; the absence or presence of surface defects; as well as their electronic and optical behavior. This is a critical step to further develop those materials, understand their properties, and move toward application (Terrones et al. Nano Today 5:351–372, 2014). In this chapter, we will review the main properties of graphene-based materials based on their dimensionality. We will discuss the effect of dimensionality on the electronic and optical properties of these materials as well as a novel route to tune properties and characterize the growth of carbon layers and stacking orders.