Building Complex Hybrid Carbon Architectures by Covalent Interconnections: Graphene–Nanotube Hybrids and More

Abstract

Graphene is theoretically a robust two-dimensional (2D) sp(2)-hybridized carbon material with high electrical conductivity and optical transparency. However, due to the existence of grain boundaries and defects, experimentally synthesized large-area polycrystalline graphene sheets are easily broken and can exhibit high sheet resistances; thus, they are not suitable as flexible transparent conductors. As described in this issue of ACS Nano, Tour et al. circumvented this problem by proposing and synthesizing a novel hybrid structure that they have named "rebar graphene", which is composed of covalently interconnected carbon nanotubes (CNTs) with graphene sheets. In this particular configuration, CNTs act as "reinforcing bars" that not only improve the mechanical strength of polycrystalline graphene sheets but also bridge different crystalline domains so as to enhance the electrical conductivity. This report seems to be only the tip of the iceberg since it is also possible to construct novel and unprecedented hybrid carbon architectures by establishing covalent interconnections between CNTs with graphene, thus yielding graphene-CNT hybrids, three-dimensional (3D) covalent CNT networks, 3D graphene networks, etc. In this Perspective, we review the progress of these carbon hybrid systems and describe the challenges that need to be overcome in the near future.

Design Considerations for Unconventional Electrochemical Energy Storage Architectures

“…Yet, presently designed graphene foams suffers from macroscopic dimensions and a severe miniaturization (by at least two orders of magnitude) may be required to truly benefi t from the wonder properties of graphene. [ 536,675,[681][682][683] Finally, it should be mentioned that caution must be exercised with respect to utilizing graphene or graphene analogues derivatives for energy storage or other electrochemical devices and applications. [ 684,685 ] Radich et al have recently demonstrated that rGO is not suitable platform for TiO 2 based photocatalysis.…”

Graphene as a functional layer for semiconducting carbon nanotube transistor sensors

“…Moreover, because of its strong π-π interaction toward other graphitic nanomaterials resulting from the similar sp 2 -carbon conjugated structures, graphene has been incorporated in building novel hybrid multidimensional carbon-based nanomaterials that combine respective advantages from different components [26], such as rebar graphene, which utilizes the carbon nanotube networks to reinforce the mechanical strength of graphene for transparent and conductive thin films [27], and graphene-CNT carpets that exhibit superior conductivity and ultra-large specific surface area for high-performance supercapacitors [28]. However, to our knowledge the use of functionalized graphene both as a functional and robust interface in carbon based hybrid systems has not been explored.…”

Towards the understanding of the graphene oxide structure: How to control the formation of humic- and fulvic-like oxidized debris

“…GO also appears to be an excellent precursor for synthesizing more complex and hybrid graphene-based materials [10] at affordable costs. The GO structure consists of a graphene layer modified with oxygen functional groups decorating the basal plane and edges [11].…”

“…An advantage of GO when compared to pristine graphene flakes lies in the presence of functional groups that make it ideal for applications involving composites in which matrix-filler bonding is preferred [14,18]. Therefore, the control in the fabrication of novel hybrid materials and 3-dimensional structures [10] require the development of an adequate and reliable synthesis model which could deep our knowledge in understanding the detailed structure of GO and its reduced forms. Over the past decades, different models for the structure of graphite oxide were proposed, mainly consisting of a homogeneous oxidized structure [19][20][21][22].…”