Synthesis graphite exfoliation

Manning, T.J., Mitchell, M., Stach, J. and Vickers, T. (1999) Synthesis of exfoliated graphite from fluorinated graphite using an atmospheric-pressure argon plasma. Carbon, 37, 1159-1164. 

Synthesis of exfoliated graphite as well as the reduction of graphite oxide was carried out by Zhu et al. (2010). A short-time direct exposure to microwave irradiation was used to bring about these reactions. 

Du X S, Xiao M, Meng Y Z, Hay A S (2004), Facile synthesis of exfoliated and highly conductive poly(aiylene disulfide)/graphite nanocomposites , Polymers for Advanced Technologies, 15(6), 320-323. 

Graphite materials produced at 600-1100°C may find applications in lithium batteries and supercapacitors. Currently, similar flakes are produced in a complex process including graphitization at above 2500°C,16 followed by intercalation and exfoliation of graphite15. Here we demonstrate that synthesis of graphite from iron carbide can be done in one step at moderate temperatures. 

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. 

Fig. 2.1 Top-down synthesis methods, (a) Micromechanical cleavage (b) ion intercalation (c) graphite oxide (d) liquid-phase exfoliation.

S. Stankovich, D.A. Dikin, R.D. Piner, K. a. Kohlhaas, A. Kleinhammes, Y. Jia, et al., Synthesis of graphene-based nanosheets via chemical reduction of exfoliated graphite oxide, Carbon,... 

V. Eswaraiah, S.S. Jyothirmayee Aravind, S. Ramaprabhu, Top down method for synthesis of highly conducting graphene by exfoliation of graphite oxide using focused solar radiation, Journal of Materials Chemistry, 21 (2011) 6800. 

Carbon materials used for the commercial synthesis of carbon fluoride include natural graphite, petroleum coke, activated carbon, carbon black and carbon fiber. Experimental carbon materials include residual carbon, exfoliated graphite, fullerenes and other unique carbons and carbon inserts. The degree of graphitization of carbon material varies continuously, so it is not simple to define the exact boundary between carbon and graphite. The product formed... 

Kim et al. have developed a solution-phase synthesis method of ultralarge GO sheets involving pre-exfoliation of graphite flakes. Such large GO sheets spontaneously form lyotropic nematic phase at a very low concentration in water [125]. They produced self-assembled brick-Uke GO nanostmctures by simple casting of GO dispersions and drying in ambient conditions. These free-standing GO papers... 

Figure 3.7 Experimental setup diagram (left) and exfoliation of the graphite anode (right). Liu, N., Luo, E, Wu, H., Liu, Y, Zhang, C., and Chen, J. One-step ionic-liquid-assisted electrochemical synthesis of ionic-liquid-functionalized graphene sheets directly from graphite [91]. Copyright Wiley-VCHVerlag GmbH Co. KGaA. Reproduced with permission.

Wang, H., Kakade, B.A., Tamaki, T, and Yamaguchi, T. (2014) Synthesis of 3D graphite oxide-exfoliated carbon nanotube carbon composite and its application as catalyst support for fuel cells. / Power Sources, 260, 338 - 348. doi 10.1016/j.jpowsour.2014.03.014... 

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