Engineering 3D Graphene-Based Materials: State of the Art and Perspectives

Abstract

Graphene is the prototype of two-dimensional (2D) materials, whose main feature is the extremely large surface-to-mass ratio. This property is interesting for a series of applications that involve interactions between particles and surfaces, such as, for instance, gas, fluid or charge storage, catalysis, and filtering. However, for most of these, a volumetric extension is needed, while preserving the large exposed surface. This proved to be rather a hard task, especially when specific structural features are also required (e.g., porosity or density given). Here we review the recent experimental realizations and theoretical/simulation studies of 3D materials based on graphene. Two main synthesis routes area available, both of which currently use (reduced) graphene oxide flakes as precursors. The first involves mixing and interlacing the flakes through various treatments (suspension, dehydration, reduction, activation, and others), leading to disordered nanoporous materials whose structure can be characterized a posteriori, but is difficult to control. With the aim of achieving a better control, a second path involves the functionalization of the flakes with pillars molecules, bringing a new class of materials with structure partially controlled by the size, shape, and chemical-physical properties of the pillars. We finally outline the first steps on a possible third road, which involves the construction of pillared multi-layers using epitaxial regularly nano-patterned graphene as precursor. While presenting a number of further difficulties, in principle this strategy would allow a complete control on the structural characteristics of the final 3D architecture.

Covalent organic functionalization of graphene nanosheets and reduced graphene oxidevia1,3-dipolar cycloaddition of azomethine ylide

“…31,[33][34][35] Moreover, where the 3-dimensionality of graphene-based materials becomes fundamental, like in gas and energy storage applications, [36][37][38][39] the modication of graphene's surface with heteroatoms or functional groups allows enhanced performance. [40][41][42][43][44][45][46] Nonetheless, to nely control or intentionally design the binding sites of functionalizing molecules on graphene's surface while preserving the high quality of its unique structure remains an open challenge.…”

The Concentration of C(sp3) Atoms and Properties of an Activated Carbon with over 3000 m2/g BET Surface Area

“…The motivation of the present work was to systematically study the structure of the AC-TR material including reliable estimations of the sp 3 phase content by various techniques. Such information is important for engineering 3D graphene-based materials [ 47 , 48 ].…”

Graphene and Graphene-Like Materials for Hydrogen Energy

“…Indeed, individual sheets obtained during the synthesis of graphene form agglomerates and/or have defects, so the real specific surface is usually 150–600 m 2 /g (less often about 2000 m 2 /g). It should be noted that the specific surface area of three-dimensional (3D) graphene materials can reach 3500 m 2 /g [ 11 , 12 ]. These materials will be discussed separately below.…”

“…It is very difficult to pack graphene sheets into a multilayer 3D structure while maintaining a distance of about 0.7 nm between them, which is optimal for physical sorption [ 15 , 34 ]. At present, researchers mainly use the two approaches: the creation of disordered porous frameworks and the incorporation of molecular columnar spacers between the graphene sheets [ 9 , 11 , 12 ]. The precursors in both versions are graphene flakes or reduced graphene oxide (RGO) flakes.…”

“…8 ) [ 35 ]. Simulation gives good results of about 4 wt %, but the gravimetric capacity in various experiments reaches only 1.5 wt % [ 12 ].…”