Date Published: September 02, 2018
Publisher: John Wiley and Sons Inc.
Author(s): Muqing Chen, Runnan Guan, Shangfeng Yang.
Fullerene has a definite 0D closed‐cage molecular structure composed of merely sp2‐hybridized carbon atoms, enabling it to serve as an important building block that is useful for constructing supramolecular assemblies and micro/nanofunctional materials. Conversely, graphene has a 2D layered structure, possessing an exceptionally large specific surface area and high carrier mobility. Likewise, other emerging graphene‐analogous 2D nanomaterials, such as graphitic carbon nitride (g‐C3N4), transition‐metal dichalcogenides (TMDs), hexagonal boron nitride (h‐BN), and black phosphorus (BP), show unique electronic, physical, and chemical properties, which, however, exist only in the form of a monolayer and are typically anisotropic, limiting their applications. Upon hybridization with fullerenes, noncovalently or covalently, the physical/chemical properties of 2D nanomaterials can be tailored and, in most cases, improved, significantly extending their functionalities and applications. Here, an exhaustive review of all types of hybrids of fullerenes and 2D nanomaterials, such as graphene, g‐C3N4, TMDs, h‐BN, and BP, including their preparations, structures, properties, and applications, is presented. Finally, the prospects of fullerene‐2D nanomaterial hybrids, especially the opportunity of creating unknown functional materials by means of hybridization, are envisioned.
Fullerene is the first member of the nanocarbon family featuring a closed‐cage structure, and the discovery of C60 as the first fullerene by Kroto et al. in 1985 disclosed a new era of nanoscience.1, 2 Among all known allotropes of elemental carbon, fullerene is the only soluble species with a definite spherical molecular structure merely composed of sp2‐hybridized carbon atoms.3 The unique 0D structures of fullerenes enable their use as important building blocks to construct supramolecular assemblies and micro/nanofunctional materials applicable in optoelectronic devices, catalysis, biomedicines, and so on.4, 5, 6, 7, 8 In particular, C60 has a triply degenerate low‐lying lowest unoccupied molecular orbital (LUMO), rendering an excellent electron‐accepting ability for holding up to six electrons and facilitating the formation of donor–acceptor dyads.6 Furthermore, fullerene can be regarded as an electron‐deficient polyalkene, and thus, it is chemically reactive.9 This makes the derivatization of fullerenes feasible so as to extend their functionalities.
g‐C3N4 is the most stable allotrope of carbon nitrides under ambient conditions with the 2D, π‐conjugated plane of polymeric tri‐s‐triazine connected via tertiary amines (Figure19).115 As an emerging graphene‐analogous 2D nanomaterial, g‐C3N4 also has a high thermal and chemical stability as well as unique electronic and optical properties, making it a promising material for photocatalysis and energy‐related applications.116, 117 The advantage of g‐C3N4 as a metal‐free catalyst toward organic pollutants and water splitting for hydrogen production under visible‐light irradiation has been extensively reported.116, 118 However, the photocatalytic activity of bare C3N4 is limited due to the high recombination rate of photogenerated electron–hole pairs resulting from its relatively large band gap (≈2.7 eV) and the existence of contact resistance between the nanosheets.116 Hence, the photocatalytic activity of g‐C3N4 needs to be improved so as to extend its photocatalytic applications.
As another type of emerging inorganic 2D semiconducting nanomaterials, TMDs have been attracting widespread attention due to their intriguing electronic, optical, and mechanical properties. Molybdenum disulfide (MoS2) is the most representative TMD, consisting of hexagonal rings with Mo and S atoms alternately located at the hexagon corners. Monolayer MoS2 has the direct band gap of ≈1.8 eV and a high in‐plane carrier mobility, enabling broad applications in electro and photocatalysts, photovoltaics and photoelectric devices.124, 125
The discovery of C60 as the first fullerene in 1985 marks a milestone in nanoscience due to its unique spherical molecular structure merely composed of sp2‐hybridized carbon atoms. As the only soluble species among all known nanocarbons derived from the 0D structure, fullerenes have been popularly used as important building blocks useful for constructing versatile noncovalent/covalent nanohybrids with a variety of functional materials, including 2D nanomaterials, as elaborately reviewed in this paper.
The authors declare no conflict of interest.