Discovering Properties of Nanocarbon Materials as a Pivot for Device Applications

57 It is rare in the history of modern science that a single area will be so productive for both fundamental research and its applications as in the field of nanocarbon materials. During last few decades several breakthrough discoveries in synthesis and fabrication of these materials have happened. Enabling materials technology has inspired thousands of scientists and engineers around the world working in physics, materials science, nanotechnology, chemistry, and other fields: 140,000 papers were published since 1991 (Fig. 1). Successes in these fields were celebrated by three major prizes,1 the 1996 Nobel Prize in Chemistry (R. F. Curl, H. Kroto, R. E. Smalley), the 2010 Nobel Prize in Physics (A. Geim, K. Novoselov), and the 2012 Kavli Prize in Nanoscience (M. S. Dresselhaus). Multiple applications of nanocarbon materials are anticipated to follow from their unique properties. The latter range from high mechanical stability and stiffness to unusual interfacial thermal conductance and optical performance. At the most basic levels all of these properties are related to the special type of carbon–carbon chemical bonding, so called sp2 hybridization, present in all nanocarbons.2 These bonds are natural in the flat, two-dimensional (2D) network, connecting carbon atoms and making a honeycomb-shape atomic lattice. The resulting material appears in the form of infinitesimally thin (just one atomic layer thick) although extremely strong film. Scrolls3 of such a film could have a spheroidal shape (fullerenes), cylindrical shape (nanotubes), may form flat or conical flakes (graphene and nanocones) or a combination of those shapes. Furthermore, these clusters may be placed in each other, making “matryoshka” (nesting doll) fullerenes and multi-wall nanotubes, “peapods” (fullerenes inside nanotubes), nested cones, fishbone whiskers, and multi-layer graphene flakes. Physical peculiarities of hexagonal lattice, and an intrinsically small size of the objects, give rise to all the advantages but also to the challenges of nanocarbon materials to be briefly outlined below. Significant mechanical strength and very high 2D electric conductance—two major physical properties of sp2-carbons—are due to the high chemical stability of sp2-bonds of a carbon atom and the delocalization of the last non-hybridized valence π-electron of the atom. These π-electrons are mobile within the whole lattice and their dynamics in a particular configuration determines electronic, optical, and interfacial thermal conductance properties of the material. Such Discovering Properties of Nanocarbon Materials as a Pivot for Device Applications