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Investigations on Exotic Forms of Carbon: Nanotubes, Graphene, Fullerene, and Quantum Dots
Published in Vineet Kumar, Praveen Guleria, Nandita Dasgupta, Shivendu Ranjan, Functionalized Nanomaterials I, 2020
Mahe Talat, Kalpana Awasthi, Vikas Kumar Singh, O.N. Srivastava
Fullerene has potential applications in different areas such as electronic devices, superconductors, sensors, and catalysts, as well as in the biomedical field (Thakral et al., 2006; Coro et al., 2016). Fullerene was firstly synthesized by vaporization of graphite rod using an Nd:YAG laser in a low-pressure environment (Kroto et al., 1985). In 1990, the Krätschmer and Huffman group prepared mg quantities of C60 with higher fullerenes (e.g., C70, C76, etc.) by a.c. arc discharge of graphite rods under a helium atmosphere (Krätschmer et al., 1990). Conventional chromatography and NMR techniques were used to separate C60 and C70 and for their characterization. In the arc discharge method, graphite was vaporized under a helium atmosphere at 100 Torr pressure and condensed soot contains fullerene is most popular method. Above 100 Torr helium pressure, CNT formation was observed. There are several reports on the formation of fullerene using the arc discharge method (Haufler et al., 1991; Diederich et al., 1992; Churilov, 2008). Recently, environment-friendly fullerene separation methods were reported by the Zeng group (Zeng et al., 2017). Fullerenes were prepared using premixed hydrocarbon flames under reduced-pressure and fuel-rich conditions (Gerhardt et al., 1987; Howard et al., 1991; Howard et al., 1992). C60 was synthesized in a low-pressure flame of benzene and acetylene (Mckinnon et al., 1992; Ozawa et al., 1999). In 2000, Hebgen et al. synthesized fullerene by the low-pressure diffusion flames method using benzene/argon/oxygen. The yield of fullerene in collected soot was determined by the high-performance liquid chromatography method. The concentration of fullerenes was well above the visible stoichiometric surface of a flame. The fullerenic nanostructures, e.g., spheroids including highly ordered multi-layered or onion-like structures are shown in Figure 8.2. Fullerenes (i.e., C60 and C70) were also prepared by the microwave synthesis method using graphite and fluorinated graphite (Hetzel et al., 2012). Using this synthesis method, carbon allotropes are produced quickly. There are various types of fullerenes, such as are alkali-doped, endohedral, exohedral, and hetero fullerenes. In alkali-doped fullerenes, alkali metal atoms fill in the space between fullerenes and donate valence electrons to the neighbouring fullerenes. It is also possible to enclose another atom inside the fullerene because of its hollow cage. This type of fullerene is known as endohedral fullerene. If the metal atom is trapped inside the fullerene, metallofullerenes are obtained. Due to the small size of C60 fullerene, endohedral fullerene was prepared using C82, C84, or higher fullerene. Exohedral fullerenes were synthesized by a chemical reaction between fullerenes and other chemical groups. In heterofullerenes, one or more carbon atoms of the cage are substituted by hetero-atoms, e.g., nitrogen or boron atoms (Coro et al., 2016).
On the surface interaction of C60 with superalkalis: a computational approach
Published in Molecular Physics, 2022
After the discovery of C60 fullerene [1], carbon nanostructures played a key role in the development of new advanced materials having potential applications ranging from solar cells to cancer therapy [2]. Due to its high electron affinity, fullerene can transport the charge effectively and consequently, can be used as a potential acceptor in photovoltaic cells [3]. Furthermore, C60 can act as an excellent electrophile and form stable C60n− systems, for n = 1–6, with the addition of electrons [4]. The space within the C60 allows encapsulating atoms or clusters, forming endohedral fullerenes [5–8]. When these atoms or clusters are attached to the outer surface of the C60, an exohedral fullerene is formed. One of the important applications of exohedral fullerene is the superconducting behaviour of M3C60 (M = alkali metal) complexes with high transition temperature [9]. The reduction of C60 is also important due to the fact that neutral C60 shows poor reactivity towards electrophiles. This reduction to fullerenides activates the fullerene cage as C60 anions become electron-rich and consequently, react with electrophiles. Varganov et al. [10] studied the exohedral and endohedral complexes of C60 with Li atom. In this work, we study the interaction of C60 and superalkali (SA) clusters, which leads to SAC60 complexes.