Tunable, self-assembled 3D reduced graphene oxide structures fabricated via boiling

To exploit the favorable mechanical and electrical properties of graphene in practical applications, control over the dimensionality and geometry of assembled graphene structures is required. Here, we report the use of boiling with reduced graphene oxide (RGO) colloidal dispersion to form self-assembled three-dimensional (3D) RGO structures. The morphology of the resulting self-assembled RGO structures could be controlled by varying the heat flux during boiling. A large heat flux resulted in continuous bubble nucleation at the surface, and consequently, the interference exhibited aggregates of RGO flakes around the bubble nucleation site due to repetitive expansion and contraction of the bubble triple line. As the water evaporated, self-assembled foam-like graphene (SFG) was formed. As the heat flux increased, more vigorous agitation occurred at the interface, which led to smaller pores in the structures. With a low heat flux, the less vigorous bubble interference dynamics led to interactions between the RGO flakes, and consequently, self-assembled bump-like graphene (SBG) structures were formed, which were not porous. The self-assembled RGO 3D structures exhibited favorable mechanical and electrical properties compared with conventional 3D self-assembled graphene- or carbon-based structures. Such controllable 3D RGO structures with good mechanical and electrical properties have potential applications.