Graphene external

Physisorption measurements showed that carbon nanomaterials exhibit rather meso- and macroporous structures (maximum micropore fraction, 15% see Table 2.1). The lowest specific surface area was measured with the platelet fiber catalyst exhibiting slightly more than 100 m2/g. The Co/HB material offers 120 m2/g of surface area, and the highest BET value was determined with the Co/ MW catalyst featuring nearly 290 m2/g. Carbon nanomaterials, though, are not really porous, as the space between the graphene layers is too small for nitrogen molecules to enter. The only location of adsorption is the external surface of the nanomaterials and the inner surface of the nanotubes. 

One synthesis approach that does not rely on CNT formation from the gas phase is molten salt synthesis. The reactor consists of a vertically oriented quartz tube that contains two graphite electrodes (i.e. anode is also the crucible) and is filled with ionic salts (e.g. LiCl or LiBr). An external furnace keeps the temperature at around 600 °C, which leads to the melting of the salt. Upon applying an electric field the ions penetrate and exfoliate the graphite cathode, producing graphene-type sheets that wrap up into CNTs on the cathode surface. Subsequently, the reactor is allowed to cool down, washed with water, and nanocarbon materials are extracted with toluene [83]. This process typically yields 20-30 % MWCNTs of low purity. 

In the pattern of CNF parallel graphene planars sticks with external diameter about 30-40 nm are presented (Fig. 1, c). 

Light-emitting diodes (LEDs) are basically a light-emitting polymer pinned between two electrodes externally connected to a power supply, where the cathode furnishes electrons to the LUMO of the polymer and the anode injects holes in the HOMO of the polymer. Once the electrons and holes recombine into the bulk of the polymer an exciton is produced which then releases its energy in the form of electromagnetic radiation [289]. Peumans et al. demonstrated the use of graphene as transparent electrodes... 

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